Sunday, 24 June 2012

Starvation, diets etc. for no good reason

I wanted to post something that's occupied everyone's mind at one point or another: losing weight. How does it work, this whole fat burning thing? How much fat is good, how much is bad? I'm not professionally educated in this domain, but that's not important since a lot my criticisms come from simple assumptions. Recently I read an interesting statement from the e-book 'Experiments with Intermittent Fasting' by Dr. John M. Berardi:
the standard North American diet is often hyper-energetic – we eat more than we burn – which leads to weight gain over time.
A good test to see if a statement makes any sense is to declare the opposite and see what comes out. In this case I came up with "A non-standard North American diet is often hypo-energetic – we burn more than we eat – which leads to death". If I had to choose sides, the former certainly looks healthier than the latter.

Even more interesting was that Dr. Berardi goes on to claim that intermittent fasting (in his definition not eating for 20-odd hours) can reverse these 'problems':
Intermittent fasting can be helpful for in-shape people who want to really get lean without following conventional bodybuilding diets, or for anyone who needs to learn the difference between body hunger and mental hunger
Unfortunately this makes no long-term sense: if you burn more calories per day than you eat, eventually you will die. This is not science; it is simple logic. For even a slight negative imbalance your fat reserves will deplete, which could take years, but at some point the reserves run out.

There are two variables to work with: calories in and calories out. Calories 'in' is the simpler of the two variables to measure, and in theory should be very exact. But it's not that simple. Imagine, if you will, that you eat four times per day and that each meal had a 100 calorie uncertainty. Think how small 200 calories is when compared to an entire meal (some beers are more than 200 calories apiece). Perhaps you ate an extra dinner roll, forgot to count in a glass of wine, or omitted a snack. These are extremely fair assumptions especially since you have to also include the errors inherent in calorie (mis)labeling in food.

Let's take this 100-calorie imbalance to the nth degree. If the mistakes are completely random (i.e. you miscount above or below the true value), then summing the errors for the day we have

Total error/day = sqrt(sum of squared errors) = sqrt(4*100^2) = 200 calories of uncertainty

Now 200 calories isn't that much to mistake per day, but unfortunately you don't get to reset this value every time you go to sleep (why would you?). As the weeks go by, the errors increase. Imagine a full year of this uncertainty:

Annual food intake 'error' = sqrt(365*4*100^2) = 3820 calories

For an entire year 3800+ calories is also small (maybe what you'd burn in a marathon). 3800 calories is close to a pound of fat. Let's change things a little. Since it's much, much more likely you'd overeat than undereat (after all our brains are programmed this way), the true error is biased. A biased error means that each mistake is made in the same direction. Therefore it would be more prudent to add together the uncertainty of each meal in the same positive direction. So suppose you unexpectedly ate a mere 50 calories more than intended for each meal (and 4 meals/day or 3 meals and one snack), then in a year's time....

Annual food intake 'error' = 365*4*50 = 73,000 calories (!!)

A measly 50 calories of 'overeating' per meal equals over 20 pounds of weight gain in a single year. The math is simple but I bet you never thought about it that way. And this calculation applies to everyone, including active people. Athletes burn more calories but few people seem to remember athletes also eat more. In fact they eat so often (and eagerly) their intake errors are expected to be much higher. According to these calculations everyone should be fat. While writing this entry I ate a 'personal sized' apple pie that turned out to contain over 600 calories. I do that sometimes. But my weight has remained unchanged for the last five years. Something doesn't add up here...

In the case of athletes, recall that different kinds of athletes have different body shapes. This will be true even if each burned the same number of calories a day. When exercising, it is the sport itself, along with your body's internal regulations, that will determine your overall physique. Doing a lot of body-building exercises will make you look like a body builder. I lost 20 pounds of fat and muscle when I switched from XC skiing to running (and have remained the same weight ever since).

How the body does regulates all these inputs is a mystery. A really cool mystery, but imagine you were your body receiving all these signals (food, energy losses, sleep). Odds are you'd prefer to keep in equilibrium for as much of your time as possible. Homeostasis is connected to metabolism, which is variable. Not eating for very long periods makes you sluggish to save energy. Some of that sluggishness is mental but with time it is quite physical. But assuming you eat enough, what exactly you eat and precisely how much of it has far, far less to do with this overall process. You can't reverse engineer yourself by simply changing your diet. By measuring someone's eating habits can I really know that much about them? How well could you guess the make and model of a car just by knowing how much gas the driver puts in the tank? (NB: the tank might not be empty!). Long-distance swimmers have more body fat than sprint swimmers but long distance runners have less than either. Do you really think this is a diet-based problem?

Among entire populations there's a similar story. When discussing excess weight, few people seem to realize that those who are fat also have a stable weight for long periods (that is few, if any, people keep piling on weight forever). If you know someone with a bit of heft to them they probably have had the same amount of heft over a number of years. Body weights do tend to creep up over time with inactivity but not at the rate I alluded to earlier (i.e. 20+lbs/year, every year). Whether active or inactive, the body has made rough a decision where it's default weight should be.

But not everyone has the same default weight; some are thin, other not. Why? Simple: throughout human history it's been an advantage in periods of starvation to put on weight easily. But at other times it has been important be lean and mobile (i.e. for hunting, historically). To prevent total population annihilation, some regularly active people have a disposition for surviving lean times while others are prepared for active times.

A handful of thin people might survive a famine by slowing their metabolism to an extreme lethargic state. It will keep you alive, but not active. All this is just our 'default' setting; it is a weak predictor of leanness when habits change. For instance there are obesity epidemics in Northern Quebec Cree communities due to inactivity. Yet a single generation past these same communities were lean when hunting using traditional means.

Our modern sedentary history is a blip on the time scale of humanity. A completely sedentary lifestyle is unprecedented, so much that we have always assumed some degree of physical work to earn our food. This causes unexpected problems for your body the same way a rodent's teeth are expected to be worn from daily use (hence constantly grow). For beavers not to chew down trees would mean eventual death by overbite, though unlikely given their habits. For the most part humans were 'meant' to exercise simply because that's how our software/hardware was designed. Some animals 'need' more exercise than others. But... starvation was never intended as a personal 'control' parameter. To lose weight by starvation is obvious. That this weight will return with a vengeance is also obvious. For such regained weight to be again eliminated by further starvations is, you guessed it, obvious (and stupid).

Two conclusions, both not in favor of Dr. Berardi's ideas:

1. Humans do not benefit from fasting. But yes, we are certainly well equipped to survive it. Even a lean athlete has around 8% body fat, enough to run him or her hundreds of miles. Elementary math can demonstrate as much. Dr. Berardi's analogy is broken: we do no need to replicate past starvation. Instead we should imitate our past activity levels. We do not require a literal imitation of our hunter/gatherer lifestyle (we don't actually know quite how they lived on a daily basis). This much we know: some eating here and there (wherever food can be found) until full while doing spurts of cardio for several hours a day is quite normal (again, historically speaking). And yes, being a little bit hungry helps you think sharply for a few hours (surprise...). But eventually it's all you're thinking about (Again, surprise...)

2. Calorie counting does not work. Eating fewer calories than you burn means death (or a decreased metabolism and increased lethargy). Because you cannot 'exactly' measure the calories in meals (as even the tiniest errors creep up until they reach absurd proportions) the notion of over-eating is a trivial one. Unless we ate exactly the correct number of calories, which we can't, it is more appropriate to say we all over eat. Especially athletes. The body pre-chooses a weight based on exercise-related inputs and makes bodyweight adjustments by variable metabolism (that post meal warmth you might feel is real). To do no exercise at all screws up the body's equations and it's anyone's guess what will happen, but probably gain a lot of weight, but you might be thin by default. By modern standards you're lucky if your default is something lean (given the current availability of food). Those same people are not so fortunate if food ran out for a whole month.

Having recently earned a PhD myself I'm less than impressed with Dr. Berardi's credentials; I have no illusions that earning a doctorate alone means anything intelligence-wise. After looking at his book I see a man with curiosity, which is good for research, but conclusions which are questionable. Not eating will, in the very short term, mean weight loss, and in a long-term way signal to your body "hey, I'd better stock up on more fat next time". This, in itself, does not require a PhD to figure out.

4 comments:

  1. Hey! Great post! I completely agree that calorie counting doesn't work because I believe the premise is flawed. I really do think that there are many other factors besides calories that matter. In fact, any studies looking at diet and weight loss where they are strictly measuring the caloric intake and weight show that the participants only lose about 30% of what they 'should' have lost due to calorie deficit. They say this is due to metabolic changes, which is probably true, in part. Graydon, you've known me for a while and you know that I've always been on the heavier side. I've recently (November) switched to the 'Paleo diet' and managed to lose close to 40 lbs. This has been the easiest weight loss that I've ever experienced, all due to changing the types of foods. I really believe that the type of calories matter and we eat an unprecedented amount of sugar (many in the forms of grains) that we would never had had access to during hunter/gatherer times. Whether or not we actually ate grains or not can be debated, but certainly not the amount. I can't imagine that anyone who is obese would stay obese if all they ate were fruits, veggies and meats.

    The aboriginal population that you mention that are obese, is it really due to inactivity or diet? There was a study on Australian aboriginals, where they put them back on their traditional diet and they all got to a healthy weight. I agree that we are less active then in the past, absolutely! But I think the food industries push the idea that activity matters more then it does because then you will still buy their 'product' and it's your responsibility to exercise.

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    1. Hey Amanda. It's been a while hasn't it? Wow, that's quite an achievement. My understanding of the paleo diet is a lot of balance. I run a lot an don't mind eating some bread a few times a day. Grains like oatmeal, homemade bread, spelt etc are all mixed in there. If you look at an athlete's diet it's mostly composed of carbs and they're healthy people (for the most part). Proportions of various food change with which paleo group spoken about. Food traveled less 10000 years ago than now, so there must be hundreds of diets that qualify as paleo. Northern communities are mostly meat. Tropical communities eat very bland root-based starches. Inland areas might not have access to fish (Norse apparently didn't eat fish while in Greenland even while available). If you can be thin while living in any part of the world then a specific diet must be weakly related to overall health. Balance within that diet, for sure. Though some athletes have had success with a high protein or high fat diet as well (since both can be broken down into carbs). Marathoners like Reid Coolsaet eat a lot of good food and lots of 'junk' too just to add calories (only so much vitamin B is needed, etc).

      My qualifier is that I think if someone eats WAY more than burned every day, eventually you signal to the body to add weight accordingly. But it'd have to be unambiguous (i.e. eating perhaps 1000+ more calories than required). Still, if/when weight is added it usually restabilizes.

      The 'french paradox' (eating rich foods without gaining weight) I recall was explained by habits of sitting down for prepared meals. Those who eat 'unconsciously' are doing so while mobile. That's a perfect recipe for a forager who'd need prepping for energy soon to be burned. But if you 'move' from the McD's to back home, that sends the signal to eat without actually exercising. Mixed messages for the body... The paleo diet seems to make one think about their food (the best chance of any diet is any that makes you aware of what you eat. Diets aimed at limiting intake will fail 100% of the time). Paleo removes unconscious eating but it'd say it's still roulette without the exercise, so for some it might work, others not. By contrast you're guaranteed to be shaped by your activity level.

      I saw a good talk recently where the conclusion was weight being a much worse predictor of health than activity level. He said something like "doctors keep trying to track weight changes in patients, but most forget to ask about their exercise habits. My data show doctors shouldn't care nearly as much about weight as exercise as the latter is far better correlated to overall health"

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  2. Hello again! I forgot to check back to see if you replied to my comment :) Anyway, it's been a year and a half now for me on paleo and I believe I have more insight then before. I totally agree that there would have been hundreds of different "types" of "paleo diets" but before agriculture, we certainly didn't eat grains or dairy (or processed foods and sugar). I honestly believe that the documented (I can find references, but I'm on my phone now) addictiveness of wheat and sugar, and appetite stimulating properties if wheat causes you to eat way more. I really don't believe it has anything to do with "paying more attention to what you're eating." Honestly, if it was really that easy to lose weight, there would be WAY less obese people in North America.
    I'd been trying to lose weight, unsuccessfully, for most of my adult life. Trying many different diets including weight watchers where you have to track every bite that goes into your mouth. I've spoken with tons if friends over the years who have tried to lose weight via the traditional "high carb, low fat" diet and they're universally hungry while dieting. When I started paleo, my appetite decreased significantly! I was eating about 30-50% of the amount of food and I was "allowing" myself to eat until I was full. I attribute that to the appetite stimulating effects of wheat. Cutting out wheat made my appetite so much lower then before. Maybe not everyone is susceptible to these effects and that could explain why some people never seem to get fat. I don't know, but I do think there needs to be much more research on the matter.
    I don't really think that macro nutrient ratios matter a whole lot. You can still eat paleo and eat high carb by eating lots of potatoes and fruit. I really think it's the grains, sugar and processed foods that are messing people up.

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    1. I've been thinking it over and I too have never purposely avoided eating fat, or for that matter instinctively eaten nothing but carbs. That's where some of the confusion might be: for all I know I AM on a paleo diet and just don't know it. When people say high fat, low carb, protein or whatever it could just be in proportion to what they ate before and not relative to their nearest neighbour.
      The one thing never enough discussed is fibre. Carrot cake has so much fat in it because carrots are amazing at absorbing it. So too are mushrooms, celery, potatoes, pastas dishes, cereals, and so on. I think of fibre as the scaffolding holding the other three guys together. But even that wasn't mentioned in an otherwise interesting debate: http://www.sportsscientists.com/2013/02/the-low-carb-high-fat-diet-debate-and.html My arrogant opinion is that sport science is some of the weakest science (not that it has to be, just that it is).

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