This Is Why You're Gaining Weight In The Winter

If you find yourself gaining a bit of weight every winter, you are far from alone. A 2000 study by the National Institutes of Health found that people gain an average of one pound during the cooler months. This is less than many people would expect, and is in fact several pounds less than the participants estimated for themselves — so you may be gaining less weight during the winter than you think. That being said, the study also found that most people don't tend to shed the extra weight over the rest of the year, so even if the weight gain is just a pound, years worth of extra weight gain during winter could really add up.

It is no wonder people gain weight during winter, as a 2006 study published in the European Journal of Clinical Nutrition found that people tend to eat slightly more and exercise slightly less during fall and winter compared to spring and summer. Some people may be tempted to pin down this difference to the yearly quest for a "summer body" when the weather gets hot, but there may be more to the story.

Biology and weather can affect our diet and exercise routines

A 2014 study published in PLOS One found that other animals besides humans also eat more during the winter. Considering other animals aren't under more pressure to look thin during the summer than during the winter, this suggests that seasonal fluctuations in diet may have biological and not just social causes.

Dr. Andrew Higginson of the University of Exeter argues that because food was often hard for pre-industrial humans to find during winter, people may have evolved to eat more during the cooler months so that they could have more fat stored in case they had trouble finding their next meal.

"Storing fat is an insurance against the risk of failing to find food, which for pre-industrial humans was most likely in winter," he says.

As if that wasn't enough, cooler months set up a bunch of obstacles in the way of people's workout routines. As Eat This points out, the cold can discourage people from getting out of the house and exercising, and the lack of sunlight causes people to produce more melatonin, which can make people too sleepy to work out.