Sickness & Disease in the Summertime? It’s not Lyme Disease. It’s your Air Conditioner. Oh yeah, it makes you fat, too.

It seems there’s something to be said for “fresh air and sunshine.”

Out West, it’s not uncommon on many days for windows & doors to be kept open – albeit with screens – to keep out bugs. And frankly, there’s a thing present in the East, that in large part is absent in the West. Southerners call it “humidity.” Southerners subtract humidity, while Westerners add it. Either way, it’s still cooling by evaporation. It’s just that there’s an abundance of it in the South. And please bear in mind, that without humidity, it just wouldn’t be the Southern experience!

Yet, in all seriousness, I can totally understand the whys and wherefores of these findings. Frankly, they’re not surprising at all. For years, we’ve heard the colloquial voices encouraging us all to “get some fresh air.”

Turns out, there’s some truth to that… a whole lot, in fact.

Read on for the fascinating research from the University of Alabama at Birmingham.

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Your Air Conditioner Makes You Fat

Lloyd Alter
Design / Urban Design
June 21, 2012

Ran Yaniv Hartstein/CC BY 2.0

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.

Shutters in Milan/ Lloyd Alter/CC BY 2.0

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.”

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http://www.treehugger.com/urban-design/your-air-conditioner-makes-you-fat.html

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Does My Air Conditioner Make Me Fat?

Identifying Hidden Causes of Obesity

Could central air be inflating spare tires across the country? In a study published last summer in the International Journal of Obesity, UAB biostatistician David Allison, Ph.D., and colleagues suggest that air conditioning and other factors may play surprisingly important roles in America’s weight crisis.

For years, health providers and the media have focused on the “Big Two”—food marketing and institutionally driven reductions in physical activity—as the major causes of our society’s soaring obesity problem, to the near-exclusion of other important influences, says Allison. He notes that while these factors have quite plausibly contributed to the decades-long rise in obesity, much of the evidence is circumstantial. And while he does not discount the importance of the Big Two, Allison makes a strong case for considering 10 additional causes.

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.

Another contributor to obesity may be lack of sleep. Intuitively, it seems that more sleep would lead to less energy expenditure and increased weight gain. But Allison’s team found that the hours of sleep a person gets each night is actually inversely related to Body Mass Index (BMI), a measure of obesity. Restricting sleep may actually produce increased hunger and appetite, contributing to obesity.

Two other culprits identified by the UAB study—smoking cessation and certain medications—are less of a surprise. The Centers for Disease Control and Prevention estimates that between 1978 and 1990, smoking cessation was responsible for about 25 percent of the increase in the number of overweight men in the United States and 16 percent of the increase in the number of overweight women. And medical professionals have long been aware that some medications, including antidepressants, contraceptives, and antihistamines—most of which were introduced or saw a dramatic increase in use over the past three decades—can lead to weight gain.

Allison says other explanations for obesity include an increase of endocrine disrupters such as DDT and PCBs in the environment, which may affect hormones in the body and contribute to increased body fat.

America’s changing demographics may hold another key to weight changes, as some age and ethnic groups have a higher prevalence of obesity than others. Marriage and family matters also play a role. The probability that two individuals will mate may be linked to a similarity in weight levels, which can increase the number of obese offspring. Women are waiting longer to have children, and the older a woman is at childbirth, the higher may be the risk that her child will become obese. Separate research reveals that maternal obesity may promote the same problem in subsequent generations.

“We are not discounting the potential effects of food marketing and reductions in physical activity,” Allison says. “But we believe addressing these additional factors could have implications for both treating and preventing obesity.”

— Robert D. Phillips, M.D., M.P.H.
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http://main.uab.edu/show.asp?durki=107063