I suspect the world would be better if that percentage were even greater.
Big Fat Lies by Gary Taubes
I’m back again fighting the battle against my weight, cholesterol and blood pressure. As a guy who tries to be very rational and very scientific, I’m constantly looking for (and constantly frustrated) by the lack of rigorous and useful scientific data that guides me in trying to change my behavior to have a better health outcome. In doing this, I am frequently frustrated.
For instance, when I was a kid, we were warned about eating to much sugar. Sugar, it was said was the major cause of hyperactivity and tooth decay. In fact, both of those appear to be myths. Parents have been told that their kids will be more hyper when they’ve had sugar, and often apply a purely subjective standard for their children’s behavior depending upon whether they know if they’ve had sugar or not. And of course pure sugar is relatively less of a problem than starchy carbohydrates because tooth decay is primariy caused by a bacteria which feeds on sticky starch which remains stuck to teeth, which causes them to emit acids which attack tooth enamel.
By the late seventies, the blame had shifted to dietary fats. It seems logical: if you are getting fat, it’s probably, well, because you ate too much fat. So, a huge industry began which fed America based upon this wisdom: we saw the creation of larger and larger amounts of “low-fat” and “non-fat” foods, which we as Americans bought in vast quantities. And, the net result of all this was that obesity rates skyrocketed. In other words, when millions of Americans did what experts told them to do and lower their fat content, they became fatter and fatter, and dramatically so.
The Atkin “revolution” told us that much of what we learned was a lie: that in fact it wasn’t fat which made us fat, it was carbohydrates. Our new demon was bread: you could eat all the steak you wanted, as long as you didn’t eat any of that bread.
The fact of all of this is that food metabolism is very complex, and much of what people say about diet is not only incorrect, but in fact can’t possibly be correct. As a for instance, the conventional wisdom is that “a calorie is a calorie”. It doesn’t matter if you eat fats or carbs or proteins, it all doesn’t matter. If you have an excess of around 3500 calories, you will put on a pound of fat.
But this can’t possibly be true. Let’s say that it were true, and you were one of those lucky people who “hasn’t gained a pound since college” (let’s say that’s 10 years ago). That means that in the span of 3653 days (we’ll round), your total caloric intake as compared with your energy expected has to be balanced to within 3500 calories. That requires a precision of about one calorie per day. I burn a calorie in a few seconds of walking on a treadmill. Does that make any sense to anyone?
There obviously has to be more at work here.
I got on this track courtesy of Jay Parkinson’s blog. He’s an MD, and was writing about a retailer who pulled a T-shirt from their stores which carried the message “Eat Less”. He said that he thought it was a bad thing, because anorexia accounted for a mere 1% of the population, while 35% of us were obese. According to figures provided by UN FAO (and linked by Parkinson) Americans consume on average 3790 calories per day. The American Heart Association suggests that I eat between 2000 and 2400 calories as a moderately active adult male in my age group. Let’s say that my activity level burns 2200 calories per day, but that I am one of these “average” Americans. This means that I am overeating to the tune of 1590 calories per day. I should put on more than a pound every three days. If weight gain (and loss) were really as simple as Parkinson would have you believe, the real question isn’t “why can’t I seem to get thin” but rather “why aren’t we all bursting our skins?”
Someone left this link to a talk by Gary Taubes on Jay’s discussion board. I think it’s pretty interesting, and points out some of these fallacies and the likely causes. I think that if I could internalize some of the lessons, it might prove to be helpful.
Comments
Comment from Alan Yates
Time 6/8/2010 at 4:09 pm
I find the entire subject of body energy homoeostasis quite fascinating. Self interest mostly, as I have battled the adipose tissue daemon my entire life. On that front I am happy to report I am winning somewhat, losing 35 kg in the past three years with no changes to diet. Rather I just gave up car transport and now walk everywhere, averaging about 35-40 km per week at 6.5-7 km/hr.
I don’t see it as especially surprising that the body may have mechanisms that regulate energy uptake so precisely, we have homoeostatic mechanisms that regulate many things with great precision. That said, I do suspect the precise dynamics are far more complicated than current simplistic in vrs out fetish.
The yo-yo effect so many people fall into with “dieting” is not very surprising. I recall those wonderful predator/prey differential equation simulations you ran some time ago. Body mass homoeostasis is much more complicated, and such oscillation over time when you kick the system with modulation of its forcing functions should be expected.
I have a few areas of thought about the entire system that I have never seen much research on. One is how much effect sebum production has on lipid storage, I for one have fairly oily sweat and wonder how much is lost via that exocrine system. Thermal homoeostasis is obviously our largest output, but metabolic turn-over associated with anabolic repair processes may be underestimated. I also strongly suspect the body’s investment in repair is down-regulated when it is not being challenged by the micro-trauma of exercise. This might explain the protective and anti-ageing effects of exercise.
Another area I have seen some suggestions of research on is ketone volatility. When you enter ketosis the ketone bodies produced circulate in your blood and I strongly suspect a fair amount evaporates from the lungs and skin. I have not seen much research on the uptake side of things, I wonder what mechanisms the body has for controlling absorption, especially as many nutrients are actively transported across the gut wall.
I also wonder about chronobiology forcing on seasonal variations in adipose storage. It stands to reason that we may have evolved a mechanism to alter the preferences of fat storage over burning to control our adiposity seasonally. The relatively recent addition of clothing, thermal environmental control and night-time electric lighting may affect this quite dramatically. There has been some research suggesting sleep/wake cycles are strongly correlated with weight maintenance.
If you consider human evolution and geographical distribution prior to high speed transport it is quite likely that a great variety of alleles coding for different set points and control preferences may have evolved. What works for one human may not be optimal for another. Micronutrient status probably effects the particular pathways the body uses by preference and the regulation systems, like everything in living organisms, it was “engineered” by evolution so is likely what we might consider a hacked-up mess of compromises and good-enough solutions. Only careful research will provide more practical understanding of population variations and perhaps better control strategies.
Comment from Wouter ZS1KE
Time 7/1/2010 at 3:01 am
Some interesting stuff here http://www.bodyforwife.com/genetics.html
Comment from Nancy
Time 10/12/2010 at 2:59 am
His presentation did make me look at what I had always considered proven. I never thought to check if there was real solid evidence backing up the hypothesis i have been told. I see how Taube’s hypothesis of eating less carbs could make one less fat in terms of the amount of insulin that it produces but i do not see it solving the problem of obesity. Especially when he makes a point to say how fats are good for you because of how they affect insulin. Exercise does play a considerable role in helping obesity no matter what he says about it making you more hungry or slowing down your metabolism in order to maintain balance.
Comment from anders
Time 6/8/2010 at 2:08 am
there must be a negative feedback loop in there somewhere which stabilizes intake/consumption to within one (kilo)calorie or so…