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Theory Challenged on Why People Get Fat

Common wisdom is that some people get fat because they have the “thrifty” gene, which helped our ancient ancestors survive during times of famine. It helped folks metabolize and store food more efficiently so that they were able to keep on keeping on. Now, according to “Ancient genes, modern meals” (Science News, 9/20/14, pages 18-22) come several challenges to this theory which may not help you become a “normal” eater, but hopefully will help you see yourself differently if you are large sized.

Andrew Prentice of the London School of Hygiene and Tropical Medicine asserts that “food shortages affect fertility and that women with the highest body weight have greater reproductive success” and “plumpness is an advantage not because thinner members of a population are less likely to die, but because they are less likely to bear children and pass their genes to the next generation.”

John Speakman of the Energetics Research Group, University of Aberdeen, Scotland, has a “drifty” gene hypothesis: “obesity might not have been actively selected for, just passively allowed to float into the human genome.” He’s saying that being fat stayed in the gene pool because it was neither greatly advantageous nor advantageous.”

Says diabetes researcher Elizabeth Genné-Bacon of Yale University, “Europe has a lengthy history of war, disease and frequent food shortages, but European descendants have a lower incidence of diabetes than the indigenous people of the Americas and Pacific Islands who may have had less food turmoil in their distant past.”

Other theories include the possibility that “a taste for the Western diet” may be the culprit because “humans evolved to eat foods with the natural sweetness of fruit (not Froot Loops), leaving bodies that are not able to cope with sugar and fat at every checkout stand.” Or that “As humans relied less on fighting to survive, a propensity for obesity emerged.” And, finally, a climate effect theory that says “Survivors in colder parts of the world amplified genes that help preserve body temperature—a higher metabolic rate that keeps the body warm would confer some resistance to obesity. Genes adapted for warmer climates would lower metabolic rate, burn calories at a slower pace, and make the body inclined to accumulate fat.”

Note that that these theories come with no judgments about fat. So view your size from these vantage points and stop blaming yourself for it.