Does Cold Weather Make You Store Body Fat?
We've all heard of animals storing enough fat to get them through winter hibernation, but what about humans?
Is there some biological mechanism that makes us cling to fat in colder weather, or are those extra pounds simply the result of overindulging during the holiday season?
Surprisingly, there is some evidence that human bodies do enter a sort of hibernation mode during cold, dark months.
There is a biological basis for this behavior. Human hibernation mode seems to be caused by changes in levels of serotonin, cortisol, testosterone, and the lipoprotein lipase enzyme.
Serotonin is the feel-good chemical our brains produce to promote a sense of well-being. The Journal of Clinical Endocrinology and Metabolism has published studies linking winter weather to decreased serotonin production.
Our brains commonly produce less serotonin in winter months. This decrease is felt most profoundly by people who suffer from Seasonal Affective Disorder (SAD), but even a slight decrease can lead to behaviors that promote weight gain.
When serotonin is low, the resulting stress and sadness can lead to emotional eating. These binges usually include large quantities of foods that are high in fat and carbohydrates.
These "comfort foods" provide a temporary mood lift, but overconsumption can result in unhealthy weight gain.
People who experience SAD often find it difficult to perform routine tasks, much less exercise and prepare healthy foods. They might require drug therapy to become fully functional during the winter months.
Cortisol is the despised "stress hormone" that tells our bodies to pack on the fat - especially around the midsection. Our bodies produce cortisol in times of stress in an attempt at self-preservation.
Unfortunately, between the stress of the holiday season and natural dips in serotonin levels, cortisol can cause winter weight gain.
Studies have found that cortisol levels are lowest in the summer, and peak between November and February. That means holiday treats have a way of lingering on the belly. Cortisol also weakens the immune system, leaving us more vulnerable to colds and the flu. That means more bed rest and less activity, thus, more weight gain.
Testosterone is a hormone that promotes fat loss and muscle building. Men and women both produce testosterone; men simply produce more, which is why men naturally have more muscle mass and women have more body fat.
Like serotonin and cortisol, testosterone levels rise and fall throughout the year. Testosterone production peaks in the summer months, and dips to a seasonal low in winter and early spring - yet another reason why our bodies burn less fat during the cold months.
This enzyme is the reason why animals can live off of their stored fat during hibernation. Lipoprotein lipase, or LPL, promotes fat storage in animals and humans alike.
Researchers at the University of Colorado monitored LPL levels in men and women during summer and winter months. The subjects' LPL levels spiked during winter months, causing fat to be stored more readily.
Of course, there are other reasons why we tend to put on weight during the cold months. Consider the typical holiday season: It kicks off with a huge Thanksgiving feast, followed by televised football games and days or weeks of high-calorie leftovers.
Next comes Christmas. In the weeks leading up to the holiday, many of us get bombarded by friends and coworkers bearing holiday treats and will quickly result in weight gain over the weekend. Hectic travel schedules make fast food a near-necessity.
Once we reach our destinations, we spend most of our time indoors, visiting with loved ones. Who has time for the gym?
Another holiday feast is followed in short order by New Year celebrations flowing with alcohol and snacks. By the time we get back to our regular eating schedule, we've usually packed on a few pounds. Is it any surprise?
As you can see, biology and tradition are working against us during the winter months. While that's not exactly good news, it does let you know what to expect.
Stay as healthy as you can by limiting your splurges, staying as active as possible, and not getting discouraged if your weight loss slows down during the winter.