Your Air Conditioner Makes You Fat

Written by Lloyd Alter

There is the old joke in Houston about how you define a pedestrian: A person looking for their car. People don’t do a lot of walking in the heat; perhaps that’s why McAllen-Edinburg-Mission in Texas is the most obese region in America and Boulder, Colo. is the least.

But there may be a more important reason than the driving; it may be biological. A study by David Allison of the University of Birmingham found that air conditioning might make you fat.

One of the most intriguing factors listed in the study is the “reduction in variability of ambient temperature.” The widespread use of central heating and air conditioning means that most homes and offices are now kept at a relatively constant temperature year-round. Allison’s group found evidence that this causes the body to expend less energy, because it does not have to work to warm up or cool down, potentially leading to increased fat stores. In the South, where obesity rates are the highest in the nation, homes with central air increased from 37 to 70 percent between 1978 and 1990.

One doctor wasn’t so sure, telling ABC: “Since people stay thin in all different climates, it is unlikely [air conditioning] plays much of a role.” But that’s not much of an answer; People in the southern United States are fat, and people in Italy or France generally are not. In Italy, people often live in apartments with thick walls that resist the heat, and as seen in the photo I took in Milan last month, everybody has external shutters pulled down to keep the heat out. Not many people have air conditioning because they know how to keep cool. Few of the people I saw there were obese.

Somebody is going to say in comments that “correlation does not imply causation”, they always do. But there IS a correlation.

There are other factors that might come into play; heat suppresses your appetite which reduces your food intake, while air conditioned restaurants are attractive cool places to be, which increases it.

Other effects of Air Conditioning:
A French study found that “people working in air-conditioned offices are almost two-and-a-half times more likely to suffer from respiratory infections than those in naturally ventilated buildings.” From the Independent:

In the study, the French doctor examined the levels of air temperature, humidity, airborne bacteria and fungi in both air-conditioned and naturally- ventilated buildings. He found that seven out of eight symptoms were associated with exposure to air conditioning at work.

Dr Teculescu said: “Upper respiratory tract infections such as the common cold are one of the main reasons for absence from work. Air conditioning circulates the air and can carry airborne bacteria and fungi.”

This post was originally published by TreeHugger.

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First photo: Thinstock; second photo: Lloyd Alter

Disclaimer: The views expressed above are solely those of the author and may not reflect those of
Care2, Inc., its employees or advertisers.

Kathy P.

1:06PM PDT on Sep 25, 2012

i could believe this. just get outside more, people!

September 25
send a green star

Dale O.

8:24AM PDT on Jul 31, 2012

Intriguing, but my air conditioner stays on. The humidity the other day made it feel as if it were 108F, then 104 yesterday. Too hot for me. Will take long walks at night, eat a balanced diet and then wait for the -40 winters to roll around. In that case, there is so much heat rising from the first floor apartments that I never need turn on the heat, even have to open windows.

The 16 year old blind obligate carnivore that owns me is purrfectly happy that I have the air conditioner on. She has threatened me with no purrs for an entire year if her Tortie coat has to endure this heat without an a/c. That is enough to convince me right there!

July 31
send a green star

denise d.

5:01PM PDT on Jun 30, 2012

Dent H. --you are very funny. (possibly missed your calling??)
Pamela C.--you should be fined for soliciting a website.
Anyway, my comment is--when it is very hot I don't feel like eating much especially "comfort foods". I like light items like salads and fruits. In the a/c I'm oblivious and can and will eat anything. I live in Florida but try not to use a/c whenever possible. I normally only use (in my home) from Memorial Day to Labor Day. (which is what many northerners do). My friend's think I'm nuts. The goal is to keep myself cold natured so I don't have to rely on a/c or other artificial climate controls. Also it saves energy and most importantly $$$$.

June 30
send a green star

Dent H.

6:15PM PDT on Jun 27, 2012

Doggone it, I put in central air last year and I gained 2 pounds, heck no one told me it would make me fat. Isn't there some kind of truth in disclosure act for devices that can effect your health? What about the refrigerator? If air conditioning is fattening the ice box must be absolutely deadly. I called the air conditioning outfit and I was assured my unit is a low fat low carb device, so no worries. Now I can go back to worrying about important things like an unnatural fear of green bugs, Obama's war against wars and wild rutabagas.

June 27
send a green star

JosÃƒÂ¯Ã‚Â¿Ã‚Â½ M.

2:33AM PDT on Jun 27, 2012

Very interesting

Lika S.

1:53AM PDT on Jun 27, 2012

Oh, and I suppose eating habits and activity rate doesn't have a major role now, does it? In Italy, they eat fish and a lot of vegetables. They also walk or bike everywhere, and make use of public transit. Here, we drive cars and eat fatty foods with a low index carb. And we're making a big deal about air conditioning?

june t.

9:07PM PDT on Jun 26, 2012

interesting thought