Trends in Animal Obesity

Science writer Sharon Begley is one of my favorite columnists. In Fat canaries in a coal mine (Newsweek, 12/20/10), she tackles the fascinating topic of rising obesity in animals, offering some surprising research on the cause of their weight gain.

Begley starts by critiquing societal lifestyle changes as the accepted cause of Americans’ escalating weights: a decrease in physical activity due to less walking to places such as work/stores/school coupled with an increase in caloric intake due to irresponsible food industry packaging and preparation. Then she goes on to seek answers in the research of scientists working with animals. She cites the conclusion of University of Alabama at Birmingham obesity researcher David Allison who has studied marmosets for 15 years: without changes in any other variables, their weight has soared. She cites the conclusion of his collaboration with colleagues who, after reviewing the weights of other animals, including alley rats, mice, lab macaques, found that “the percentage of obese individuals has risen since the 1940s or since the oldest records they found” and that “The odds of that happening by chance are 8 million to 1.”

Because no changes had been made in their feeding or exercise, Allison concluded that there must be some other explanation which, he wonders, might apply to humans as well. What he’s saying is that we cannot continue to explain the weight increase of Americans by increased calories and decreased exercise alone. One alternate explanation might be gut bacteria which affects the calories we extract from food, that is, the more calorie-extracting microbes we possess, the fatter we get. That means that some folks are more prone to pack on pounds while eating the same amount as others.

Begley identifies other factors that affect weight and weight gain. Such as “sleep debt [which] increases blood levels of the appetite-stimulating hormone ghrelin and reduces levels of satiety-causing leptin.” She also cites, “endocrine-disrupting chemicals such as BPA, which bind to receptors that trigger proliferation of fat,” how central heating and A/C prevent the body from working hard to burn off calories, and the possibility that the adenovirus-36 could cause a weight rise.

My point here is to help you quit beating yourselves up if it’s hard for you to lose weight or keep it off. Begley’s article underscores the complexity of the subject and how different individual biologies may be. So, yes, be accountable to yourself and focus on becoming a “normal” eater, but please lay off a steady diet of self-blame.  

Best,

Karen

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