Does Air Conditioning Make You Fat?

It takes energy to maintain your body temperature. Can you somehow turn that into weight loss?

Monica Reinagel, MS, LD/N, CNS
3-minute read
Episode #103

All that heart-pounding and heavy breathing takes a lot of energy. So, for a short while, at least until you lose consciousness, I guess you could actually burn a few extra calories. But inducing severe and potentially life-threatening heat stress doesn’t strike me as a very practical weight loss strategy.

Can You Lose Weight by Turning Off the AC?

But let’s take a less extreme example. Could you get any benefit by just turning the air conditioning up a few degrees? In fact, research found that when you increase the ambient temperature from a comfortable 72° F (22° C) to a warm 80° F (27° C), people actually burn fewer calories.

When it gets hot, people tend to move around less. They expend less energy and, therefore, burn fewer calories. Fortunately, heat also tends to suppress the appetite, so people tend to eat less and it’s pretty much a wash.

Can You Lose Weight by Turning the Heat Down?

If you’re following my argument, a different question has probably occurred to you. Do you burn more calories when you’re in a cold environment? The answer is yes.

The normal temperature for the human body is 37° C, or 98.6° F. Usually, the air around us is quite a bit cooler than that. In order to keep our body warmer than the air around us, we burn calories to create heat. The cooler the environment, the more calories we have to burn to maintain that 37 degree body temperature.

Now, I’m not suggesting that you turn the air-conditioning on high in order to burn a few extra calories. In fact, for the sake of the environment and general geopolitical stability, I think it’s wise to save energy whenever we can. And, who has extra money to spend on air conditioning bills in this economy, anyway? No, if you’re lucky enough to have air conditioning, I suggest you use as little as you can get away with.

But when winter rolls around and you’re spending money to heat your house rather than cool it, you’ll finally have that win-win-win scenario Jose was hoping for: You can save money, energy, and burn a few extra calories by turning the thermostat down a few degrees.

Do You Eat More When You’re Colder?

Of course, you may also eat more when you’re colder. Research found that when the room temperature is decreased from a comfortable 72° F (20° C) to a chilly 61° F (16° C), people burned 150 or so extra calories per day keeping themselves warm. However, they also ate about 250 more calories per day. Oops.

In other words, keeping the thermostat a degree or two cooler in the winter may help you burn a few extra calories. But it will probably have a more noticeable impact on your power bill than it will on the scale!

Have a great week and remember to eat something good for me!


Does My Air Conditioner Make Me Fat?

Putative Contributors to the Secular Rise in Obesity

Energy Metabolism in Women During Short Exposure to the Thermoneutral Zone

Energy Metabolism in Humans During Lowered Ambient Temperature



About the Author

Monica Reinagel, MS, LD/N, CNS

Monica Reinagel is a board-certified licensed nutritionist, author, and the creator of one of iTunes' most highly ranked health and fitness podcasts. Her advice is regularly featured on the TODAY show, Dr. Oz, NPR, and in the nation's leading newspapers, magazines, and websites. Do you have a nutrition question? Call the Nutrition Diva listener line at 443-961-6206. Your question could be featured on the show.