Thursday, June 14, 2007

Set Point Theory


Yesterday someone in the comments asked me what I thought about "Set Point Theory".

What set point theory suggests is that a person's body, metabolism and caloric drive strive to maintain a specific preset weight and therefore if your "preset" weight is high and you lose weight, your body will just try its darndest to gain it back.

I think it's an asinine theory.

Some obvious problems (one pointed out quite rightly by the comment yesterday):

  1. Why have the world's setpoints gone up dramatically over the course of the past 50-100 years?
  2. Why is the world getting bigger so much faster (are all of our setpoints 1,000lbs?)
  3. Why do the setpoints of indiginous peoples (like the Pima Indians) seem to change the moment they step into North America?
Set point theory is something that allows folks and governments to take even less responsibility in treatment design and implementation.

Now it is indeed true that as the body loses weight it does compensate in multiple ways to try to preserve the weight it's losing. The body of course perceives weight loss as an environmental threat - an ice age or a flood or something, and so it jumps into action and changes the way the body handles certain processes, decreases something called the thermic effect of food and basically tries to hold on but it doesn't throw any magical switches to get folks to open their freezers and cupboard doors.

I don't completely discount the whole theory however. I do believe that there is a range of weight within which a person can comfortably live, but I also believe that range is very wide and it depends not only on the genetic makeup of the individual, but also his or her learned and fixed environment.

You might even stretch and say that I do believe in set point theory, but in my own version of it - I'll call it Life-Set Theory with weight being primarily lifestyle related.

People regain their weight as they regain their old lifestyles.

I say this to new patients daily,
"The more weight you'd like to permanently lose, the more of your lifestyle you'll need to permanently change"
The problem is, most weight loss efforts don't really do much to address lifestyle. Weight loss usually involves a food regime - either overt overall restriction and hunger or the magic food approach of this food's good and that food's bad. Those approaches are of course non-sustainable becase they invoke the suffering of hunger or of blind, thoughtless restriction. Any weight lost through suffering will be gained back when the suffering stops and the person reverts back to their prior life that might have led them to have weight to lose, but was easy to live.

The environment also of course matters. Look at the Pima Indians - heaviest people in the World in Arizona and healthy weights back home in Mexico. I'd imagine this would work in reverse too. For example, take someone who's lost weight with a restrictive approach while working a sedentary job in an urban environment and plop him or her down on a farm where they've got to work all day long and there's no access to food other than what they cook and grow themselves. Do you think their "set point" will have them magically gain? Of course not, because their environment no longer allows for their prior calorie rich lifestyle.

So to sum up this rant. For me lifestyle dictates set point. Change your lifestyle and eating patterns (combining hunger prevention strategies like frequent eating and increased protein with calorie awareness and an explicit lack of forbidden foods) and you've definitely got a shot, but do remember with lifestyle change it's not necessarily the changes that are difficult, it's change itself.

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5 comments:

  1. Anonymous8:56 am

    Excellent post. I must admit I did think that the set point was based on science until now.

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  2. I guess my set point is out of whack because I gained weight when I was binge eating and not exercising and lost weight when I started taking long walks, going to the gym and eating sensibly. I must have one of those magic set points that raises and lowers itself according to my behaviour.

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  3. Charles2:49 pm

    "Why have the world's setpoints gone up dramatically over the course of the past 50-100 years?"

    They haven't. Take US - the average weight gain over the "obesity epidemic" is 7-10 lbs, and far less in the "thin" subset of the population. Most set point theories postulate a 15-20 lb range around set point as maintainable, so 7-10 isn't denting that, it's just shifting things slightly due to diet and/or lifestyle. However, a thin person will struggle mightily to be obese for long (prison studies have shown this directly, actually), and an obese person mightily to be thin, since the weight change range is often in the hundreds of pounds.

    "Why is the world getting bigger so much faster (are all of our setpoints 1,000lbs?)"

    This is essentially the same question, see above.

    "Why do the setpoints of indiginous peoples (like the Pima Indians) seem to change the moment they step into North America?"

    Very similar question. Within the weight range around the set point, diet, exercise, etc can vary things.

    There is A LOT of data supporting a body mass set point. Consider some of these:
    http://www.nytimes.com/2007/05/08/health/08fat.html?pagewanted=1&_r=1

    http://www.sciam.com/article.cfm?id=interview-with-rudolph-l

    Or this quote from Jeff Friedman who discovered and obesity gene in mice:

    “Over the course of a decade, a typical person consumes approximately 10 million calories, generally with only a modest change of weight. To accomplish this, food intake must precisely match energy output within 0.17% over that decade. This extraordinary level of precision exceeds by several orders of magnitude the ability of nutritionists to count calories and suggests that conscious factors alone are incapable of precisely regulating caloric intake. Those who doubt the power of basic drives might note that although one can hold one’s breath, this conscious act is soon overcome by the compulsion to breathe. The feeling of hunger is intense and, if not as potent as the drive to breathe, is probably no less powerful than the drive to drink when one is thirsty. This is the feeling the obese must resist after they have lost a significant amount of weight. Obesity is not a personal failing. In trying to lose weight, the obese are fighting a difficult battle. It is a battle against biology, a battle that only the intrepid take on and one in which only a few prevail.” Jeff Friedman, 2003, Science

    Why would variations in body weight not be like height or other clearly genetically determined attributes? People are getting taller over the generations - is it because diet controls height, and if only a person would eat differently they could be taller (or shorter)? Of course not. Yes, you can lose weight, often a lot, but the more you move from your set point, the more your body will fight you, and the stronger your will power will have to be.

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  4. I get the impression (from your recent review of his new book) that you don't much like Gary Taubes, but he addresses the set point theory really well in his book, Good Calories, Bad Calories:

    "Life is dependent on homeostatic systems that exhibit the same relative constancy as body weight, and none of them require a set point, like the temperature setting on a thermostat, to do so. Moreover, it is always possible to create a system that exhibits set-point-like behavior or a settling point, without actually having a set-point mechanism involved. The classic example is the water level in a lake, which might, to the naive, appear to be regulated from day to day or year to year, but is just the end result of a balance between the flow of water into the lake and the flow out.

    When Claude Bernard discussed the stability of the milieu interieur, and Walter Cannon the notion of homeostasis, it was this kind of dynamic equilibrium they had in mind, not a central thermostatlike regulator in the brain that would do the job rather than the body itself.

    This is where physiological psychologists provided a viable alternative hypothesis to explain both hunger and weight regulation. In effect, they rediscovered the science of how fat metabolism is regulated, but did it from an entirely different perspective, and followed the implications through to the sensations of hunger and satiety. Their hypothesis explained the relative stability of body weight, which has always been one of the outstanding paradoxes in the study of weight regulation, and even why body weight would be expected to move upward with age, or even move upward on average in a population, as the obesity epidemic suggests has been the case lately." (GCBC, pp. 428-9)

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  5. I've got nothing against Gary Taubes, never met the guy.

    That said, I thought his latest book was an affront to helping patients with weight management and that it championed the very same oversimplifications that Gary rages have been wrong with weight loss books for decades.

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