Tuesday, July 03, 2012

Air Conditioning and obesity

I ate lunch at my favorite diner. Great food, but too much.

Sometimes I put enough aside; but not today. I ate the whole thing.

After lunch I left the cool hole-in-the-wall and walked into the great heat wave of 2012 (which will seem benign in 2022). I walked slowly back to the office, trying not to touch myself.

I blame it on the air conditioning. If China Restaurant hadn't been pleasantly cool, I know I'd have stopped sooner. 

Of course there would be other consequences of a world without air conditioning. I'm relatively slender, and I feel the heat. If I were heavier, the heat would be even more uncomfortable. Another incentive to weigh less.

So is modern air conditioning a factor in our losing battle with fat?

The question has been asked ... 

International Journal of Obesity - Putative contributors to the secular increase in obesity: exploring the roads less traveled June 2006

...The thermoneutral zone (TNZ) is the range of ambient temperature in which energy expenditure is not required for homeothermy. Exposure to ambient temperatures above or below the TNZ increases energy expenditure, which all other things being equal, decreases energy stores (i.e., fat). This effect was shown in short-term controlled human experiments 41, 42 and the decreases in adiposity were evident in controlled animal experiments; these effects are widely exploited in livestock husbandry, where selecting the environment to maximize weight gain is critical.43 Animal44 and human45 studies show that excursions above the TNZ markedly reduce food intake. Herman45 cited a consumer survey suggesting that after an air-conditioning breakdown, restaurant sales drop dramatically...

Suggestive data, but the relationship to "TNZ" sounds dubious. The authors should have described the findings as interesting correlations with some evidence of causation, then mentioned TNZ as one mechanism among many.

I couldn't find any more recent references.


Charlie Stross said...

The air conditioning hypothesis fails to explain the rising obesity rate in the UK, where domestic aircon penetration is well under 3% of dwellings, and it's still under 20% of business premises. We've been having hotter or wilder/wetter summers lately, but it's still a rare day that tops 30 degrees in England, and if we ever saw 30 degrees on the thermometer in Scotland it would be a new all-time high record. Nevertheless: obesity? We haz it.

JGF said...

It was proposed as one of 10 possible contributing causes, but not as a primary cause. Presumably obesity is a complex beast, a mixture of culture and biology and environment -- including our microbiome cloud.

In a cool nation it would be like having air conditioning all the time ...

Doubt there will be a lot of research into this. Not as though decreasing air conditioning use, or Pigovian AC taxes, will be popular. So it's kind of academic ...