I wonder how you’d go about reconciling the simple thermodynamics model of weight gain with this finding:
The trillions of bacteria that live in the gut — helping digest foods, making some vitamins, making amino acids — may help determine if a person is fat or thin.
The evidence is from a novel experiment involving mice and humans that is part of a growing fascination with gut bacteria and their role in health and diseases like irritable bowel syndrome and Crohn’s disease. In this case, the focus was on obesity. Researchers found pairs of human twins in which one was obese and the other lean. They transferred gut bacteria from these twins into mice and watched what happened. The mice with bacteria from fat twins grew fat; those that got bacteria from lean twins stayed lean.
The study, published online Thursday by the journal Science, is “pretty striking,” said Dr. Jeffrey S. Flier, an obesity researcher and the dean of the Harvard Medical School, who was not involved with the study. “It’s a very powerful set of experiments.”
What I’m referring to as the “simple thermodynamics model of weight gain” is the frequently assert belief that weight gain or loss can be determined based solely on calories consumed as food and calories expended as exercise. Despite the piles of evidence against it, the theory is remarkably persistent.
One of the things that strikes me about the experiment above is that it provides an alternative explanation for why we’ve been getting fatter as a society. It might not be due simply to eating too much and exercising too little even if that does play a role. The use of antibiotics, known to affect the intestinal flora, might play a role, too.
Maybe someday we won’t treat being fat as a character flaw and will start treating it as an actual, possibly communicable disease.
Hat tip: Glenn Reynolds