Drinking Coffee = Higher Adiponectin = Lower Body Fat Percentage?

Want to lower your body fat? Coffee might an option. (Photo by annais)

Adiponectin is a protein hormone that modulates several metabolic processes related to weight gain. Adiponectin levels are inversely correlated with body fat percentage (link) – for example, diabetics have lower levels of adiponectin than non-diabetics, and losing weight increases adiponectin levels.

Since adiponectin affects glucose uptake and insulin sensitivity, and low adiponectin levels are a risk factor for developing diabetes and metabolic syndrome, it raises the question of whether increasing adiponectin levels might be a good thing.

A study from last year looked at the effects of coffee on adiponectin levels in 665 Japanese males (link). Adiponectin levels were measured from serum samples, and coffee consumption was assessed using a self-administered questionnaire. The questionnaire also included green tea consumption, so that the effects of green tea and coffee could be compared.

The participants who drank more coffee tended to be younger, more likely to smoke, and less likely to drink alcohol. The mean age of non-drinkers was 49.9, while the mean age of those who drank at least three cups per day was 48.2. Interestingly, non-drinkers had the highest mean blood pressure (systolic 129.5 and diastolic 80.7 mmHg) of all groups, while those who drank 1-2 cups per day had the lowest (123.1 and 76.7) – although this could just be due to the age difference. There were no significant differences in BMI or physical activity between coffee drinkers and non-drinkers. Unfortunately, body fat percentage was not measured.

However, adiponectin levels were significantly higher in those who drank coffee compared to non-drinkers. In those who drank none, 1–5 cups per week, 1–2 cups per day, and >2 cups per day, adiponectin levels were 5.95, 6.51, 7.05 and 6.89 mcg/mL, respectively.

When confounding factors such as age, smoking status and BMI were adjusted for, adiponectin levels were still positively associated with coffee consumption. There was a significant dose-response relationship between coffee consumption and adiponectin levels. However, there were no significant differences in adiponectin levels between those who drank 1–2 cups and those who drank >2 cups per day.

Green tea was not associated with adiponectin levels. There was also no association between coffee consumption and total cholesterol, HDL or LDL.

Although this study included only men, similar findings have been reported in women. In one study, diabetic and non-diabetic women who drank at least four cups of coffee per day had higher adiponectin levels than those who didn't drink coffee regularly (link). Interestingly, caffeine consumption was also associated with adiponectin levels. Perhaps the adiponectin-increasing effect of caffeine is diminished or blocked by other compounds such as L-theanine in green tea.

There's also one interventional study on habitual coffee drinkers that found coffee consumption increased adiponectin levels (link). Unlike in the study on Japanese males, total cholesterol and HDL also increased – possibly because the intake of coffee was higher (8 cups per day) at the end of the experiment.

Based on this and other studies, the key points are:

a) those who drink coffee have higher adiponectin levels than those who don't
b) those who have higher adiponectin levels have lower body fat percentage

All in all, while correlation does not prove causation, it seems plausible that drinking coffee could help maintain a lower body fat percentage and avoid type II diabetes and metabolic syndrome.

If you have personal experiences with coffee and weight loss, feel free to share them in the comment section below. For more information on weight and fat loss, see these posts:

Why Are Thin People Not Fat?
A Year of Intermittent Fasting: ADF, Condensed Eating Window, Weight Loss, And More
Green Tea and Capsaicin Reduce Hunger and Calorie Intake
The Twinkie Diet: Thoughts on Weight Loss and Cholesterol

The Twinkie Diet: Thoughts on Weight Loss and Cholesterol

You can lose weight on any diet, but is it healthy? (Photo by OkayCityNate)

A few days ago, CNN reported on a nutrition professor who lost 27 pounds in ten weeks eating mostly Twinkies (link). Not only that, but health markers improved too – LDL went down and HDL went up.

Some people seem to think the results resolve the old question of whether calories are all that matter in weight loss. After all, if you can lose weight by eating Twinkies, Doritos and Oreos, what else could it be than calories? Surely that's just about the worse diet you can have.

While I'm obviously a big fan of self-experimentation, I think the results have been misrepresented in some cases. What do I mean by that? Let's look at the experiment and the results a bit more closely. Here's a quote from the article:

For a class project, Haub limited himself to less than 1,800 calories a day. A man of Haub's pre-dieting size usually consumes about 2,600 calories daily. So he followed a basic principle of weight loss: He consumed significantly fewer calories than he burned.

If we take the 2,600 calories daily as the correct figure, then for the ten weeks, Haub was running an 800 calorie deficit. It's hardly surprising that he lost weight. When you cut back enough on your energy intake, you start losing weight – in this sense, a calorie is a calorie.

But since this is an experiment with only one participant, it's impossible to say whether more or less weight would have been lost if the diet had been different. Did all the sugar he was eating prevent him from losing the maximum amount of body fat? There's no way to tell.

There are some hints, however, that it's not all about calories. The amount of calories consumed may be the primary factor in how much weight or fat is lost, but that doesn't rule out other factors. In rats, for example, green tea increases weight loss during calorie restriction. The rats consuming green tea burned more of their body fat and absorbed less fat from the diet, despite eating the same amount of calories.

In real life settings, the argument that a calorie is a calorie is difficult to examine, because the number of calories we burn is not constant – it depends on many variables. We now know, for instance, that genetics play a role. Some people have a hard time putting on weight, because the more they eat, the more calories they burn. They may get an urge to exercise more, for example. And anyone who's tried different diets knows that some foods make you more energetic than others, despite having a similar number of calories.

But that's not all. Some people don't put on weight even when exercise is forbidden. Their bodies just start using all that excess energy in other ways: increasing metabolic rate, heat production, etc. Is a calorie really a calorie in this case?

Then there's the question of how to count the absorption of calories from different macronutrients. If you divide people into two groups and feed both the same amount of calories, but have one group eating more protein and the other group eating more carbohydrates, their weights will be different. In general, high-protein diets result in more weight loss than high-carbohydrate diets.

As you can see, the question is hardly as simple as some people make it out to be. And there are more similar things that complicate the issue. Stephan from Whole Health Source has a good post on the Twinkie diet and how it relates to hormones and fat mass regulation, and I'm sure there are other health bloggers who have picked up on the same article.

Putting the calorie issue aside, perhaps the thing that aroused the most interest was the part about improved biomarkers. Sure, you can lose weight eating a terrible diet, as long as your eating very little, but shouldn't that wreck your health in other ways? Apparently not:

Haub's "bad" cholesterol, or LDL, dropped 20 percent and his "good" cholesterol, or HDL, increased by 20 percent. He reduced the level of triglycerides, which are a form of fat, by 39 percent.

But that's not really big news. You see similar things happening in many studies where the participants are put on weight loss diets, regardless of what the diets are like. Even in the studies where overweight people are put on the conventional low-fat, high-carb diet – which is not really a good approach for improving cholesterol levels, glucose and insulin – these health markers improve while they're losing weight. As a spokeswoman for the American Dietetic Association says in the article:

"When you lose weight, regardless of how you're doing it -- even if it's with packaged foods, generally you will see these markers improve when weight loss has improved," she said. 

However, as in the case of the amount of weight lost, there's really no way to tell based on this experiment whether his health markers would have changed differently on another diet with the same calories. Low-carb and low-fat diets have very different effects on cholesterol during a calorie deficit, for example (note also how the subjects lost more weight during the low-carb diet despite eating more).

Since the study only lasted for ten weeks, the fact that his LDL and triglycerides decreased while HDL increased doesn't say much about the long-term effects. I wonder what his cholesterol levels would have been after a year of following the Twinkie diet.

Also, there's more to cholesterol than just LDL, HDL and triglycerides. In the case of lipoprotein particles, size matters. A diet consisting mostly of sugary snacks is probably not going to do a whole lot of good for LDL particle sizes in the long run. And even when HDL and LDL levels look good on the surface, there's oxidized LDL and lipoprotein (a) to worry about.

What we can say with some certainty is that regardless of how you do it, returning to a normal weight seems healthier than being obese. In the maintenance phase, which lasts much longer, more things should probably be taken into consideration. Haub himself seems to have mixed feelings about his experiment:

"I wish I could say the outcomes are unhealthy. I wish I could say it's healthy. I'm not confident enough in doing that. That frustrates a lot of people. One side says it's irresponsible. It is unhealthy, but the data doesn't say that."

While the health markers are interesting, it would have been interesting to hear more about his experience in general. How did he feel before, during and after the diet? Was he feeling energetic or tired? How was his mood? Did he have any problems, digestion, bad skin, etc?

Before you kickstart your own Twinkie diet, note that professor Haub also had a multivitamin and a protein shake daily, which may have influenced the results somewhat. And if you've already tried a strange diet and managed to lose weight, drop a comment and tell us how it went.

For more information on diets and weight loss, see these posts:

Alternate-Day Feeding and Weight Loss: Is It the Calories Or the Fasting?
A Year of Intermittent Fasting: ADF, Condensed Eating Window, Weight Loss, And More
Green Tea and Capsaicin Reduce Hunger and Calorie Intake
Green Tea Extract Increases Insulin Sensitivity & Fat Burning during Exercise

Why Are Thin People Not Fat?

How do some people manage to stay thin despite eating a lot?

You probably know at least a couple of people who just don't seem to get fat no matter how much they eat. Some of them don't even do much exercise. But is it really true that some of us gain weight more easily than others, or do thin people just eat less calories?

Most of the studies on obesity and weight loss have been done on subjects who are overweight to begin with. A BBC Horizon documentary titled Why are thin people not fat? looked at the obesity problem from a different angle. They chose subjects who were naturally thin and stuffed them with excess calories. None of the participants had watched their food intake before, but their weight had remained roughly the same for years.

The subjects were told to eat at least double their usual calories and to avoid exercise for four weeks. The target energy intake for men was 5,000 kcal and somewhat less for women. The purpose was to find out whether naturally thin people would start gaining weight, given a sufficiently large amount of calories. It was no exercise in healthy eating either: the menu included processed, calorie-dense foods such as cakes and milkshakes. Precisely the kind of thing that should make one fat.

The documentary begins by mentioning a similar experiment done on Vermont prison inmates in 1967. The inmates were grossly overfed with the purpose of studying the hormonal changes that happen when a person becomes obese. The prisoners who signed up were promised an earlier release.

Each inmate was supposed to increase their body weight by 25 percent. However, as the experiment progressed, it turned out that no matter how high the energy intake got, some of the inmates could not reach their targets. Despite eating and eating, they just didn't gain enough weight. One of them could not increase his body weight more than 18%, even though his daily calorie intake reached a whopping 10,000 kcal.

For years, experts argued over the results of the Vermont prison study. According to the classical model of calories in, calories out, such high intakes should have led to a dramatic weight gain, especially since exercise was forbidden during the experiment. So how did some of the inmates stay thin?

This is the question that the BBC experiment tries to answer. I recommend watching the whole documentary, but here's a summary of the results:

• All participants had trouble reaching their energy intake goals
• Energy-dense foods such as chocolate made reaching the goals easier
• Some of the subjects gained more weight than others
• One of the subjects gained almost no weight but increased his muscle mass
• All subjects returned to their normal weights after the experiment

These results confirm the observations from the Vermont prison study: despite very high calorie intakes, some people have a harder time gaining weight than others. The documentary also explains how naturally thin people are able to stay thin:

• Appetite has a genetic basis
• Age, weight, and diet of the mother during pregancy influence the child's weight
• Eating habits learned during childhood carry on until adulthood
• Naturally thin people avoid excess calories instinctively
• People have a certain "natural weight" towards which the body aims
• Basal metabolic rate plays a strong role in energy expenditure
• The feeling of hunger is related to the number of fat cells
• The number of fat cells can grow but never diminish

There's a lot of debate these days over the importance of basal metabolic rate (BMR) in the calories in, calories out model. It's interesting to note that nobody eats the exact same amount of calories per day, and yet weight remains in a very narrow range (at least in healthy, thin subjects). The one subject who stuck to his 5,000 kcal intake but gained almost no weight supports the idea that there is a kind of setpoint that the body tries to maintain regardless of calorie intake.

It also looks like in some people, the mechanisms to preserve the natural weight setpoint are stronger than in others. Increased heat production is obviously one way to maintain weight during increased energy intake. Some people (Michal Eades comes to mind) have also argued that as the number of calories eaten increases, the body starts to burn them by increasing small, almost involuntary movements such as tapping your fingers, moving your legs, etc. – physical activity which is not considered exercise but still uses up extra energy. I think this theory makes sense.

The last two points of the list are especially interesting. There are two key attributes to fat tissue: the size and number of fat cells. The number of fat cells in your body is typically pretty much determined during adolescence. Thus, eating affects first and foremost the size of your fat cells. As you store and burn energy, the fat cells in your body grow and shrink accordingly.

That's not all there is to it, however. If you keep eating even after the fat cells have grown to their maximum size, at some point the body will begin to produce new fat cells to store all that extra energy. The tendency to produce more fat cells probably depends on the individual.

The problem is that according to our current understanding, the number of fat cells can only be increased, never decreased. This means that any new fat cells produced as a result of (prolonged) overeating will always stay with you. What's worse, as the purpose of fat cells is precisely to store energy, the body will now send more signals of hunger to your brain to keep those fat cells filled up. Obviously this makes following diets that rely only on cutting back on calories very difficult.

The overall message of the documentary is that being naturally thin is a combination of many factors, some of which are genetically determined and some a result of the environment. Of course, individual choice also plays a role, but the studies on small children given unlimited candy show that even before we have the capability to think rationally about our food choices (kids will eat as much candy as they desire), there are differences among people.

For those who have to struggle to maintain or lose weight, things are more difficult – though not impossible by any means. It just means paying attention to your diet, venturing beyond governmental recommendations, and trying on yourself what works. I've had many overweight people tell me how difficult it is to lose weight, and then when I ask them if they've tried for example a basic low-carb diet, they've either tried it for a few weeks and quit, or they've deemed it "unhealthy", because all they can picture is Atkins on his deathbed and slices of bacon clogging their arteries.

Are you a naturally thin person who can eat and eat without gaining weight? Are you the exact opposite? Share your experiences in the comment section!

For more information on diet and weight loss, see these posts:

Alternate-Day Feeding and Weight Loss: Is It the Calories Or the Fasting?
Green Tea and Capsaicin Reduce Hunger and Calorie Intake
A High-Protein Diet Is Better than a High-Carbohydrate Diet for Weight Loss
Low-Carb vs. Low-Fat: Effects on Weight Loss and Cholesterol in Overweight Men

Alternate-Day Feeding and Weight Loss: Is It the Calories Or the Fasting?

Weight loss with one slice of pizza one day and anything you want on the next? (Photo by nettsu)

I don't know if you noticed, but a new study on intermittent fasting recently made headlines in several media. The paper basically found that alternate-day fasting (or "on-off fasting" as it was named in some articles) helped obese adults to lose weight.

That's not a huge surprise, really. If you're obese, it means you eat too much of the wrong foods and probably too often. Fasting every other day means you'll at least be eating them less often, if not less per se. However, the conclusions that have been drawn in various articles from the study seemed a little suspicious to me, so I decided to read the whole paper.

Indeed, the authors themselves appear to be somewhat confused as to what really caused the weight loss. So without further due, let's take a closer look at what the study actually found (link).

Study design

12 obese women and 4 obese men were recruited for the study. Mean age was 46 years, mean body weight was 96.8 kg, and mean BMI 33.8. Not exactly the featherweight league.

The study consisted of three phases. The first one was a 2-week control phase, during which the subjects were told to maintain their usual weight by eating and exercising as they normally would. In the second phase, which lasted for 4 weeks, all participants were given a standard menu containing 25% of their baseline energy needs on the fast days. On the feeding days they could eat as much as they wanted. The third phase, also 4 weeks, was similar to the second one. The only difference was that the participants could choose what they wanted to eat on their fasting days, as long as they only ate 25% of their baseline needs.

So, the first thing that sets this study apart from how most people do intermittent fasting is that they didn't consume zero calories during their fast. They just ate significantly less. The second thing is that the fasts began and ended at midnight. Most people (including me) start and end their fast sometime during the day, because it allows them to eat at least once a day. If the participants went to sleep before midnight, their "fasts" were significantly longer than 24 hours.

Their standard diets were also less than optimal in my opinion. Things like chicken fettucini, vegetarian pizza, chicken enchilada, cookies, and crackers aren't exactly paleolithic foods consistent with the idea of intermittent fasting. But then, this wasn't a paleo study, which explains why they were fed high-carb, low-fat foods. For the third phase, they were given diet tips by a registered dietitian:

On the ad libitum food intake day, subjects were instructed to limit fat intake to <30%> dairy options.

So more carbs and less fat once again. They probably took some of this advice and applied for their feeding days as well, which makes me wonder if they wouldn't have lost even more weight had they opted for low-carb foods instead. Still, as you can see from the results below, they did manage to lose weight even with this diet.

Results

During the first phase, there was no weight loss. This is unsurprising, since all the participants just kept on eating whatever made them obese in the first place. During the eight weeks of alternate-day fasting they did lose weight, however.

In the second and third phase the subjects lost weight at a rate of ~0.7 kg per week. At the end of the study, they had lost about 5.6 kg, most of which was fat. Mean BMI decreased from 33.7 to 29.9, while body fat percentage dropped from ~45 to ~42%.

Cholesterol levels were also reduced as a result of alternate-day fasting. HDL remained the same, but LDL decreased by almost 25%. This to me is a more impressive result than the weight loss, which I think could've been greater with proper food choices.

Systolic blood pressure was lowered by 4.4 mm Hg, but diastolic blood pressure remained the same. Heart rates varied throughout the study, but at the end, they were about 4 beats per minute lower than in the beginning.

Discussion

Okay, so everyone lost some weight and improved their LDL/HDL ratio on this modified version of intermittent fasting. But what exactly is behind these results? The first thing that came to my mind as I was reading the paper was: how much were these people eating on their feeding days? Surely that would have a drastic effect on weight loss.

Unfortunately, there's no mention of this in the paper. Yes, they were told they could eat ad libitum, but apparently they were not told to keep a record of what or how much calories they ate when they were not fasting. I know food diaries are generally unreliable (people tend to underestimate how much they eat), but it would've been better than nothing. The authors seem surprised that the subjects lost as much weight as they did:

We predicted that subjects would lose a total of 4.5 kg fat mass after 8 wk (on the basis of a 75% decrease in energy intake on the fast day, with no change in energy intake on the feed day). The actual fat mass lost (5.4 kg) exceeded our predictions.

With no change in energy intake on the feed day? I'm not sure where the authors got the idea that when you eat very little on one day, the next day you won't be extra hungry and compensate. That's certainly not my experience. On the contrary, I fully compensate for any missed calories by just eating twice as much the next day. Certainly not compensating can be done if one wants to, which may be what happened here:

This indicates that these subjects were also limiting their energy intake on the feed day, which may have occurred because the subjects knew they were enrolled in a weight loss trial.

On the other hand, some articles in the media (such as this one) have reported that there was a slight compensation going on:

On non-fasting days people typically ate between 100 percent or 125 percent of their calorie needs.

This statement is probably from a press release by the authors, but the paper itself is silent on the issue. In any case, if you're eating 75% less on one day and only 25% more the next, you're still 50% short.

That, in effect, makes this a study on caloric restriction, not intermittent fasting. How is it surprising in any way that people who eat half (or even less) than what they're used to manage to lose weight? Isn't that obvious? The amount of weight they lost is pretty much what you'd expect on a low-fat, calorie-restricted diet. And based on other studies, if they'd eaten more calories but restricted carbohydrates, they'd have lost more weight.

The whole point of intermittent fasting is that you don't have to restrict your energy intake, you just don't eat all the time. If energy intake is the same and yet there are health benefits, then we can conclude that it's the fasting that is behind them. If, at the same time, calorie intake is restricted, there's no way of knowing whether it's the reduced calories or the fasting that is the cause. And of course, if intermittent fasting leads to a voluntary reduction in energy intake, that tells us something too.

I have a feeling that eating the small meal every other day magically resulted in no hunger in this study. They were probably consciously limiting their food intake even though they were told they could eat as much as they want. The fact that the authors actually expected the participants to eat only their usual calories on feeding days makes me even more suspicious.

Try eating 500 kcal on one day and then seeing how you feel the next day. If you typically eat 2,000 kcal, somehow I don't think 2,500 kcal is going to cut it. I know it doesn't for me, at least not in the long term. As for this diet being much easier to follow than old-school calorie restriction (which the paper seems to suggest), I doubt it.

For more information on intermittent fasting and caloric restriction, see these posts:

Intermittent Fasting: Understanding the Hunger Cycle
Slowing Down Aging with Intermittent Protein Restriction
Caloric Restriction Improves Memory in the Elderly
Intermittent Fasting Reduces Mitochondrial Damage and Lymphoma Incidence in Aged Mice

5 Reasons Why Dark Chocolate Is Better than Milk Chocolate

Look good? Forget it, there's way too much sugar. (Photo by .craig)

You may have thought of chocolate as a guilty pleasure, but the ancient Maya considered it the food of gods.

Granted, the Maya also thought cutting out someone's heart in a ritual ceremony was a good fun, but they did get one thing right: chocolate really is a health food. That is, as long as you buy the dark kind. In fact, the darker the chocolate the healthier it is. As good as that sugar-laden milk chocolate bar may taste, it wouldn't have made its way into any self-respecting Maya feast.

If you don't believe me, read further for three good reasons to choose dark chocolate instead of milk chocolate.

1. Dark chocolate is better for weight loss.

Even though the amount of calories in milk chocolate and dark chocolate are pretty similar (and in fact milk chocolate sometimes contains fewer calories), dark chocolate contains significantly less carbohydrates. Milk chocolate usually has about 50 grams of carbs per 100 g, while the amount of carbs in dark chocolate ranges from 8 to 35 carbs, depending on how dark it is. A chocolate with 70% cocoa has ~30 grams; a 85% chocolate has ~20 grams.

If weight loss or maintenance is your goal, the combination of large amounts of carbohydrates and fat is something to avoid. A high carbohydrate load will increase insulin secretion, which is a signal for the body to store energy as fat. The reason why low-carb diets are so effective for weight loss is their effect on insulin: even if you eat lots of fat, if there are no carbs present to drive insulin up, the energy from dietary fat won't be stored into fat cells.

Unless you consume only a small quantity or restrict other carb sources to a minimum, combining milk chocolate with a low-carb diet is going to be difficult. If your goal is to stay under 50 grams per day, 100 grams of milk chocolate fills up your entire quota. But 100 grams of 85% dark chocolate still leaves you with 30 grams to spend on other carb sources, making dark chocolate a viable option even for low-carb dieters.

2. Dark chocolate causes less aging.

Okay, so perhaps a bit of an exaggeration there, since we don't know exactly how big a role advanced glycation end-products play in the aging process. We do know, however, that the accumulation of AGEs is one of the seven biomarkers of aging, which makes avoiding them a sensible goal.

As it happens, weight gain is not the only problem with the carbs in milk chocolate. Almost all of the carbohydrate in chocolate is sucrose, which is half glucose and half fructose. Even though the word 'glycation' in 'AGE' implies that glucose is the culprit, the fact is that fructose is much more prone to cause AGEs in the body. Since the main ingredient in milk chocolate is sugar, a 100 grams of milk chocolate will also give you a hefty dose of fructose.

Dark chocolate, on the other hand, is mostly composed of fat – cocoa butter, to be specific. The fatty acid composition is 61% saturated fat, 36% monounsaturated and only 3% polyunsaturated fat, making cocoa butter very resistant to oxidation. And if you're worried about cholesterol, here's something to ease your mind: almost all of the saturated fat in cocoa butter is cholesterol-neutral stearic acid. Fructose, however, may increase triglycerides levels.

Unlike dark chocolate, milk chocolate also contains some lactose. In addition to making milk chocolate an impossible treat for some lactose intolerants, lactose also causes glycation. Lactose breaks down to glucose and galactose, and like fructose, galactose appears to form AGEs more rapidly than glucose.

3. Dark chocolate has more cocoa polyphenols.

The health benefits of chocolate are almost entirely due to the polyphenols found in cocoa. As a rule of thumb, whenever you read something good about chocolate, what they're really talking about is cocoa. Therefore, as the cocoa content of chocolate increases, so do its positive effects on health. A standard milk chocolate will contain about 30% cocoa, while premium dark chocolates usually have more than 70%.

Another thing that reduces the polyphenol content of chocolate (by 60-90%) is alkalization (link), also known as Dutch processing or simply Dutching. Alkalization was invented in the 19th century to get rid of some of the bitterness of cocoa powder and to make it more palatable. Non-alkalized cocoa powder is a more light brown in color and tastes less sweet than alkalized cocoa powder.

Nowadays Dutch processing is very common among industrial chocolate makers (link), which suggests that there's a good chance the average high-sugar milk chocolate will contain alkalized cocoa. Many dark chocolates seem to use non-alkalized cocoa, however, probably because the bitterness is perceived as preferable among chocolate enthusiasts.

4. The cocoa polyphenols in dark chocolate are more bioavailable.

Even if your dark chocolate happens to be made from alkalized cocoa, you'll still get more bang for your buck in terms of polyphenols, because the polyphenols will be more bioavailable. This is again related to differences in the macronutrient composition of chocolates.

First, the bioavailability of cocoa polyphenols depends partly on the fat content of chocolate. One in vitro study showed that cocoa liquor (which is about 50% fat) retained more polyphenols than cocoa powder (about 15% fat) when submitted to a digestion model (link). The reason appears to be that the higher fat content increases the stability of cocoa polyphenols during digestion. Second, sucrose and milk protein may affect the absorption of polyphenols negatively (link).

Dark chocolate contains no milk protein, less sucrose and much more cocoa liquor than milk chocolate. The actual content varies, since different countries have different regulations on what kind of chocolates can be called "dark chocolate". The FDA, for example, states that dark chocolate must contain at least 35% chocolate liquor, while milk chocolate only needs to have more than 10%.

Also, chocolates with 40-70% cocoa are also sometimes sold as "dark chocolate", so be sure to check the ingredient list before purchase. The words "cocoa mass", "cocoa liquor", "cocoa powder", "cocoa paste", "cocoa solids", or something to that effect should be first on the list – if "sugar" is mentioned first, it's definitely not real dark chocolate.

5. Dark chocolate is more filling.

Anyone who has tried both milk chocolate and dark chocolate must have noticed that it takes much less to satisfy chocolate cravings with the latter than the former. I can personally eat 200 grams of milk chocolate (more than 1,000 kcal) in one go without having my craving satisfied. With 99% dark chocolate, a few pieces is enough. A similar effect was shown in a study from last year (link).

This, as mentioned before, is not related to energy content, because milk chocolate and dark chocolate have virtually the same amount of calories. Rather, the reason why a smaller quantity of dark chocolate is enough is probably a combination of less sugar and more nutrients. Humans generally have a preference for sweet foods, which is why we love candy when we're kids. But part of the reason why we can't stop eating candy until we feel sick is that there are no nutrients in candy, only calories. This lack of nutrients causes our body to send the satiety signal way too late.

Since dark chocolate is higher in cocoa powder, it's also higher in many nutrients, such as iron, magnesium, phosphorus, copper and manganese. Combined with the lower amount of sugar and high amount of fat, it's no surprise you get your daily chocolate fix quicker with dark chocolate than milk chocolate.

Summary

Dark chocolate contains less sugar, more cholesterol-neutral fat, and more cocoa polyphenols in a more bioavailable form than milk chocolate. Dark chocolate is also more filling, which means it takes less calories to satisfy your chocolate cravings.

Keep in mind, however, that excess consumption of dark chocolate has its downsides too. Cocoa powder is high in iron and oxalates, which are harmful in high quantities. We'll return to the subject of optimal intakes in future posts, but for now, I limit mine to 50-100 grams of chocolate per day.

For more information on chocolate, sugar, fat, and health, see these posts:

Tea, Coffee and Cocoa: All Good for Your Teeth
SAs, MUFAs vs. PUFAs: Fat Storage Depends on Type of Fatty Acid in Rabbits
Fats and AGEs: PUFAs Are Even Worse than Fructose
Low-Carb vs. Low-Fat: Effects on Weight Loss and Cholesterol in Overweight Men

A Year of Intermittent Fasting: ADF, Condensed Eating Window, Weight Loss, And More

Even with intermittent fasting, you should watch what you eat. (Photo by Bryan Bruchman)

I can't believe it's been a year since I started my intermittent fasting experiment. By now, I've gotten so used to it that most of the time it doesn't even feel like an experiment anymore. It's become more like an integral part of my diet.

Which is a good reason to spice things up a little. As I wrote two months ago, I made a temporary change to the experiment and switched from my usual 24-hour cycle of fasting and feeding to a condensed eating window of 6-8 hours just to see what happens.

I found the smaller eating window even easier than alternate-day fasting (ADF). In practice it meant that I skipped breakfast and lunch, and then had a big meal and some snacks when I got home. While at work, I only drank water, coffee and tea. During a 24-hour fast I usually get very hungry and slightly dizzy at one point close to the end of the fast, but skipping breakfast and lunch did not result in a similar feeling of hunger. Sure, I ate with good appetite once I got home, but my energy levels did not drop at all during the day.

I didn't measure my calorie intake, but based on the fact that I gained a kilo during this period, I assume I ate as least as much as I did before. So personally, cramming all of the daily calories into a window of 6 to 8 hours was not a problem. I was already used to eating huge meals, and the eating window was big enough to include lots of snacks or even another meal.

For someone considering intermittent fasting for weight loss, I would recommend either 24-hour fasts or using a shorter eating window than I did. A daily 20-hour fast with a 4-hour eating period improves insulin sensitivity and levels of circulating adiponectin, which are key factors in regulating fat storage and thus weight gain. Further, most of the studies showing benefits from intermittent fasting used an alternate-day feeding schedule.

The implication is that while an eating period of 6-8 hours is probably superior to the usual combination of breakfast, lunch, dinner, and snacks (which keeps your blood sugar constantly high), fasting between 20 to 24 is the choice with more positive studies behind it. This leads me to believe that the most important thing is not how small the eating window is, but rather how long the fasting period is. That is, while eating for 1 hour every 12 hours would technically constitute as a daily eating window of 2 hours, I suspect eating for 2 hours and fasting for 22 yields better results. Whether a 2-hour feeding window and a 22-hour fast is slightly better or worse than eating and fasting for 24 hours is unclear, but what is clear is that both work and that the latter is much easier in practice.

That said, I've been able to both lose and gain weight during my intermittent fasting experiment, depending on what and how much I eat. Anyone who claims that IF allows you to gorge on junk food while losing weight is plain wrong. Combining intermittent fasting with a low-carb diet is, in my opinion, the way to go if quick weight loss is your goal. This way you're getting the insulin benefits from fasting and the lowered insulin response from consuming few carbohydrates.

Another crucial factor would be total energy intake during the eating periods. Based on personal experience and what I've read from other people, there's a tendency to "load up" on calories just before the fast begins, whether you're hungry or not. This makes the fast much easier, because you'll be digesting the food for longer and the hunger won't begin until late the next day. For anyone who wants to get the health benefits of IF (such as reduced mitochondrial free radicals, one of the seven types of aging damage) but maintain their weight, this is probably a good idea, but for anyone else, it can easily render attempts at weight loss useless.

To counter this, my suggestion is to follow the intermittent fasting routine but to eat only when you feel hungry. If the fast is about to begin and you still feel bloated from your previous meal four hours ago, so be it. Don't try to stuff yourself with food as a pre-emptive strike if you don't feel like it. You'll probably feel the hunger pangs earlier the next day, but it'll pass after a few hours, and you'll feel more energetic afterwards.

The take-home message of the above is that despite what you may have heard, intermittent fasting by itself is no guarantee you'll lose weight. It can be used for weight loss, weight maintenance or even weight gain, depending on the implementation: the length of the fasts, the composition of the diet, and total energy intake. By optimizing those three factors, you can shift your weight into any direction you want. By disregarding them, it becomes a genetic gamble.

IF improves insulin sensitivity, which is a good thing, but the relationship between higher insulin sensitivity and weight is not as straightforward as it might seem (more on that later). The easiest way to lose weight for most people is still avoiding a high insulin response in the first place. Reading other people's experiences with intermittent fasting, it seems that most of them have the best results when they combine IF with diets that don't contain refined carbohydrates (including whole grain products), such as Atkins or paleolithic nutrition. When unrefined carbs are brought to the table, the disagremeent over the superior diet begins.

I'm now switching back to my old way of eating and fasting for 24 hours. Further evidence may prove me wrong, but at the moment, I feel that it's more beneficial for overall health than a condensed eating window of more than 4 hours. Squeezing the eating window just seems like too much of a hassle for me, though some people on IF manage to do just that.

I've also done a small experiment with dry fasting (meaning no food or water) and ketosis in my search for the optimal form of fasting, but I'll save that for another post. Meanwhile, I warmly welcome you to post your own experiences with intermittent fasting.

For more information on insulin, fasting and weight loss, see these posts:

Green Tea, Black Tea & Oolong Tea Increase Insulin Activity by More than 1500%
A High-Protein Diet Is Better than a High-Carbohydrate Diet for Weight Loss
Green Tea Extract Enhances Abdominal Fat Loss from Exercise
Slowing Down Aging with Intermittent Protein Restriction

SAs, MUFAs vs. PUFAs: Fat Storage Depends on Type of Fatty Acid in Rabbits

The stearic acid in cocoa butter is not well stored into fat tissue. (Photo by LilyBaySoap)

When it comes to storing dietary fat into fat tissue, are all fatty acids created equal?

Recently, I've been trying to find out more information on how different types of fats are absorbed and stored as adipose tissue. In particular, I would like to see direct comparisons between saturated, monounsaturated and polyunsaturated fat and how they affect weight and fat gain in humans when energy intake is kept constant. So far, I haven't had much luck finding such studies.

What I did find is an old paper that looked into how different dietary fatty acids relate to fatty acids in adipose tissue (link). In other words, the authors studied whether the ratio of saturated and unsaturated fats in fat tissue is similar to the ratio of fats obtained from diet. To answer this question, they first starved rabbits (rabbit starvation, anyone?) for 3-4 weeks to deplete their fat stores and then put them on diets with varying fatty acids to see how it affected fatty acid distributions in adipose tissue.

Fatty acid composition of the diets

Five different diets were used, each one containing 20% by weight of either palm oil, cocoa butter, safflower oil, linseed oil (also known as flax oil) or rapeseed oil. These fats were chosen because each one is rich in a particular fatty acid: palm oil in palmitic acid, cocoa butter in stearic acid, safflower oil in linoleic acid, linseed oil in linolenic acid, and rapeseed oil in erucic acid. In addition, a low-fat control diet containing only 2.2% fat was used.

All rabbits were fed ad libitum. Though rabbits presumably consume little fat in the wild, there appear to be no special problems with feeding fat to rabbits (link, link). Rabbits eating a diet high in fat do gain more weight, however.


The figure above shows the percentages of saturated (SA), monounsaturated (MUFA) and polyunsaturated (PUFA) fatty acids in each diet. As you can see, palm oil and cocoa butter are mostly saturated fat, safflower and linseed oil are mostly polyunsaturated fat, and rapeseed oil is mostly monounsaturated fat.

Saturated and unsaturated fatty acids in adipose tissue

When you feed animals various kinds of fat, you expect to see those same kinds of fat being deposited into their fat tissue, right? Saturated fat being stored as saturated fat, monounsaturated as monounsaturated and polyunsaturated as polyunsaturated. That seems logical enough but is apparently not the case.

The rabbits on diets high in saturated fat resisted the deposition of large amounts of saturated fatty acids in their fat tissue. In fact, the rabbits eating diets high in palm oil and cocoa butter had similar levels of saturated fatty acids in their adipose tissue as rabbits eating the low-fat control diet. This despite the fact that the palm oil and cocoa butter diets not only contained much more fat as a whole, but also more than twice the percentage of saturated fat relative to total fat intake than in the control diet.


The graph above shows the percentages of fatty acids in adipose tissue after each diet. As you can see, feeding the rabbits palm oil, cocoa butter or rapeseed oil resulted in a distribution that is similar to the result seen from eating the control diet. Feeding them safflower oil or linseed oil, on the other hand, resulted in a significantly different distribution, one that is high in PUFAs but low in MUFAs and SAs.

The plateau of dietary saturated fat deposition into adipose tissue does not seem to be a temporary phenomenon. To find out how long-term administration of saturated fat affected fat deposition, the authors fed two additional rabbits a diet high in cocoa butter for a year. These rabbits showed similar levels of saturated fatty acids in their fat tissue as the rabbits that consumed the same diet for only a month. In other words, saturated fat in their adipose tissue did not increase further even with prolonged intake of cocoa butter.

Individual fatty acids in adipose tissue

So the distribution of unsaturated and saturated fats in adipose tissue depends on the fat composition of the diet. As we've seen, the relationship is stronger for polyunsaturates than it is for monounsaturates and especially saturates.

What about individual fatty acids? The same discrepancy between dietary intake and adipose tissue deposition is apparent here. The palm oil diet was 164% higher in palmitic acid than the control diet, but the concentration of palmitic acid in adipose tissue was only 30% higher in the palm oil group. Similarly, the cocoa butter diet contained eight times as much stearic acid as the control diet, but stearic acid levels in the cocoa butter group were only 52% higher.

Again, things were a little different in the polyunsaturated department. The percentage of linoleic acid in the adipose tissue more than doubled on the safflower oil diet compared to the control diet, and the linolenic acid concentration in adipose tissue was 31.1% on the linseed oil diet compared to 3.9% on the control diet.

It seems that out of the six individual fatty acids studied, oleic acid (primarily found in cocoa butter and palm oil) and linoleic acid (primarily found in safflower oil) were deposited most effectively. Oleic acid (a monounsaturated fat) in adipose tissue constantly exceeded the amount of oleic acid present in the diets. Erucic acid (mainly in rapeseed oil) and stearic acid (mainly in cocoa butter) showed the least deposition.

Conclusion and discussion

Adipose tissue takes up many different fatty acids from the diet. The degree to which these fatty acids are absorbed varies, however. Specifically, a diet high in saturated fat raises saturated fat in rabbit adipose tissue only modestly, whereas a diet high in polyunsaturates increases PUFA levels in adipose tissue dramatically.

Several reasons may explain these differences in dietary and adipose tissue fat composition. First, the authors note that since the control rabbits did have saturated fat in their adipose tissue despite consuming a diet very low in fat, they presumably synthesized saturated fat from carbohydrates in the diet. Therefore, when the intake of certain fatty acids is low, the body adapts by producing them through other means, using carbohydrates or other fatty acids.

Second, when the intake of certain fatty acids exceeds certain limits, the body is able to convert dietary fats from one form into another. According to the authors, retroconversion (chain-shortening) and desaturation of dietary fats may be a necessary function of the body to ensure optimum cell membrane fluidity. That is, when saturated fat intake is very high, the body converts some of the saturated fat into unsaturated fat to keep things working properly.

This mechanism does not appear to be in place in rabbits for polyunsaturated fats, however. The fatty acid ratios in adipose tissue appear to reflect those in the diet very strongly when the diet is high in PUFAs. This makes me wonder whether a similar effect happens in other mammals, especially humans.

The authors do not report whether calorie intake varied between groups or how much actual adipose tissue the groups had. They only mention that during the 4-week experiment, all rabbits in the five experimental groups were healthy and gained weight.

For more information on fats and health, see these posts:

Blood Test Analysis: The Cholesterol and Saturated Fat Issue Revisited
Green Tea Extract Increases Insulin Sensitivity & Fat Burning during Exercise
Low-Carb vs. Low-Fat: Effects on Weight Loss and Cholesterol in Overweight Men
A Typical Paleolithic High-Fat, Low-Carb Meal of an Intermittent Faster

Intermittent Fasting: Switching from Alternate-Day Fasting to Condensed Eating Window

Thankfully, coffee has zero calories. (Photo by Erik)

Time for another update on my intermittent fasting experiment, which has been running for 10 months now. As you probably know, intermittent fasting means alternating periods of eating with periods of fasting. The length of these periods varies depending on the type of intermittent fasting one does.

So far, I've been doing the 24/24 hour cycle, meaning that I eat for 24 hours and then fast for 24 hours. This is known also as alternate-day fasting (ADF) or every other day fasting (EOD). It has worked very well for me: the fasting periods are short enough for the hunger to be very bearable but long enough to (hopefully) see some long-term benefits such as improved insulin sensitivity and reduced mitochondrial damage. If you want to read more about what intermittent fasting is like in practice, I've written blog posts on my typical day and my typical high-fat, low-carb meal.

Starting yesterday, I've switched my eating schedule a little and experimented with another version of intermittent fasting, known as the condensed eating window. Essentially, this just means eating only during certain hours of the day. The difference to the 24/24 hour cycle is that the eating period does not continue onto the next day. A popularized version of this is the Fast-5 Diet, which promotes an eating window of 5 hours.

The way I do it is that I fast during morning and day and then break the fast when I get home from work. If I stop eating at midnight, this results in daily fasts of 16-18 hours and eating windows of 6-8 hours. So no breakfast and lunch but a big dinner and evening snacks.

There are various claims as to whether this kind of diet is healthy. One study suggested that eating only one big meal instead of the usual three may result in poorer insulin sensitivity and glucose tolerance and slightly higher blood pressure. On the other hand, body weight and stress hormone levels were reduced.

As discussed in the links above, the methodology of the study seems somewhat suspect. In any case, I won't be eating just one huge meal, but spread my energy intake throughout the 6 to 8 hours. For weight loss purposes eating only once per day may work, but I'm attempting to maintain my weight.

For more information on diets and health, see these posts:

Intermittent Fasting: Understanding the Hunger Cycle
Low-Carb vs. Low-Fat: Effects on Weight Loss and Cholesterol in Overweight Men
The Effects of a High-Fat Diet on Health and Weight: Does It Raise Cholesterol?
How Does Fructose Affect Triglyceride and Cholesterol Levels?