In a post last week, I wrote about why I believe most New Year’s resolutions to lose weight fail: those resolutions are based on the notion that shedding pounds is a matter of character … i.e., if you just have enough discipline to eat less and spend more time on the treadmill, you’ll lose weight.
As someone who tried simply eating less and spent many hours on a treadmill (I even bought one for my apartment) without getting leaner, I don’t believe losing weight is about character. I believe it’s (mostly) about chemistry, which is why weight-loss plans that rely on changing a fat person’s character are bound to fail.
I’ll have more to say on that later. For now, I just want to share some bits from an old study (1960) that I apparently downloaded some time ago and then forgot to read.
The handful of subjects in the study fell into three categories: 1) naturally thin people, 2) fat people who had previously demonstrated that they could lose weight by restricting calories, and 3) fat people whom the researchers labeled as the “resistant obese.” They wrote this about the “resistant obese”:
All had very small appetites, and none of these subjects lost weight even during observation in the hospital for prolonged periods of time.
By contrast, one of the naturally lean subjects was described as:
… a twenty-five year-old woman who is healthy, but literally unable to gain weight despite an excellent appetite.
The question the researchers wanted to answer was whether fat people and thin people release and burn fatty acids at similar rates if they’re fasting. So they had all the subjects fast from dinner until the next morning, then measured the concentration of free fatty acids in their blood. Then they extended the fast for a full 24 hours and took the same measurement at various intervals.
Here’s what they found: in the morning, the fat people generally had higher levels of fatty acids in their blood than the thin people did. But over the course of fasting for 24 hours, the naturally thin people experienced a sharp rise in the level of fatty acids in their bloodstreams. The fat people who’d previously demonstrated they could lose weight by restricting calories experienced a milder rise in the level of fatty acids in their bloodstreams. The “resistant obese” people experienced almost no rise at all in the level of fatty acids in their bloodstreams.
The researchers noted that in an earlier study, naturally thin subjects who were restricted to a high-fat diet of 1,000 calories per day showed a sharp rise in blood ketones over the next week, while obese subjects on the same diet showed a much lower rise in ketones. Ketones, as you know, are a by-product of burning fat for fuel.
So taken together, here’s what those two studies suggest (at least about the subjects who were studied): when naturally-thin people eat very little or not at all, they release a lot more fatty acids from their fat cells, and they burn those fatty acids for fuel. “Resistant obese” people, on the other hand, don’t release extra fatty acids when they eat less or not at all, and therefore don’t make up for the calorie deficit by tapping and burning their body fat — at least not to nearly the degree the thin people do.
Remember that in describing the “resistant obese” subjects, the researchers noted that they had small appetites and failed to lose weight even under observation in a hospital. In a discussion among several researchers included at the end of the paper, the leader researcher makes this statement:
This phenomenon of people who do not lose weight is really the most tantalizing thing that confronts physicians. There are these people who can live on 600 calories and not lose any weight. On what are they surviving? If we measure their basal metabolism in terms of calories, we get figures in excess of 600 calories per twenty-four hours. It would seem that on this diet they are in a caloric deficit all time, but still are not losing any weight. I am still an admirer of the laws of thermodynamics, but these people seem to be thermodynamic paradoxes.
Small appetites. Couldn’t lose weight even while under observation at a hospital. Didn’t release or burn more fatty acids (not to any significant degree) even while fasting for 24 hours. Able to live on 600 calories per day without losing weight, causing a researcher who worked with them to label them as “thermodynamic paradoxes.”
Meanwhile, the naturally-lean people released lots of fatty acids and burned them for fuel soon after they stopped eating – including that twenty-five year-old woman who couldn’t gain weight in spite of her “excellent” appetite.
Does anyone believe the fat people in this study just needed more discipline and character in order to become thin? Or does this sound like a problem rooted in chemistry?