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
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Does Air Conditioning Make You Fat?
My friend Jose recently forwarded me an article suggesting that spending a lot of time in air conditioning could cause you to gain weight because your body won’t have to work as hard to cool you down. Apparently, some researchers found that in the Southern United States—where the summers are very warm—obesity rates have increased as air conditioning has become more widespread.
If that were really true, Jose reasoned, we could lose weight, save money and conserve energy—just by turning off the air conditioner in the summer! Jose is always one to look for the win-win situation.
Of course, there’s always a chance that correlations, such as the one these researchers observed between obesity rates and the number of people with central air conditioning, are just due to coincidence. And I strongly suspect that this is one of those cases.
For one thing, it doesn’t really make sense. One reason we often say “burning calories” is because burning calories creates heat. Why would your body create heat if it were trying to cool down?
How Does Your Body Cool Itself?
Inducing severe and potentially life-threatening heat stress doesn’t strike me as a very practical weight loss strategy.
Actually, there is one time when your body might burn more calories when it is trying to cool down. In extremely hot conditions—dangerously hot conditions—your heart rate will increase and you’ll start panting. That is your body’s frantic attempt to cool you down by circulating blood from its overheated internal organs to the extremities, which (hopefully) are a little cooler, and by increasing evaporation from the membranes in your mouth and lungs.
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!
References
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 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.