Do Genes Make Us Fat?

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Do Genes Make Us Fat?

Some people can eat whatever they want, whenever they want, and never gain an ounce. Others seem to put on weight just walking past a bakery. If you’re in the second category, life may feel a bit unfair.

Of course, many physical characteristics differ widely according to the genes we’ve inherited from our parents, including weight. Recent research indicates that dozens of genes affect body weight to some degree, most by only a tiny amount. Together, however, they significantly influence how likely you are to gain weight.

Rarely, mutations in certain genes cause massive obesity, typically from early in childhood. One such gene makes leptin, a critical fat cell hormone discovered in the 1990s that tells the brain and other organs when enough body fat has been stored. People without leptin act as if they’re in a state of perpetual starvation, with insatiable hunger, no matter how heavy they become. Leptin treatment in this genetic syndrome produces a dramatic transformation. Almost immediately, hunger subsides and metabolism improves, leading to effortless weight loss, sometimes totaling several hundred pounds.

Unfortunately, this is the only example of a miracle drug cure for obesity, and it would only work for the few dozen people worldwide with this genetic form of leptin deficiency. Leptin treatment has minimal effect on other causes of obesity. All other available drugs produce modest weight loss at best, and carry risk of serious side effects. Fortunately, for the vast majority of us, genetic tendency isn’t destiny.

In any event, genes can’t explain the epidemic of obesity. Since the end of World War II, most people in developed nations have had access to an abundance of food, but obesity prevalence didn’t begin rising significantly until the 1970s in the United States, the 1980s in Europe, and the 1990s in Japan. The obesity epidemic developed far too fast to be attributable to genetic changes. Although genes haven’t changed rapidly, the environment has.

The most obvious culprit in our environment is all the highly processed carbohydrate that flooded the food supply during the low-fat craze of the last forty years. These foods raise insulin levels and program fat cells to hoard too many calories. Cut back on them, as I recommend in my forthcoming book Always Hungry?, and you can literally change the activity of your genes — leading to weight loss without the struggle.

Exported from Medium on July 6, 2016.

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