High Heat: How It Works, And Why Being Fat Adds To Risk

It includes some fascinating physiological facts: Heat makes your heart beat faster to increase blood flow to the skin. For every Centigrade degree that your body's "core temperature" rises, your heart has to beat 30 more times per minute. And once your core temperature hits 103 degrees, organs may begin to fail — in other words, I can't resist saying, you're cooked.

I knew that old people were particularly at risk, but the LA Times reports that obese and diabetic people are as well:

People over age 60 are most vulnerable to suffocatingly hot conditions. But if you're not fit, if you're overweight or if you suffer heart disease, diabetes or respiratory problems, you're also at high risk because these conditions can hamper the body's ability to regulate its core temperatures in extreme heat.

Fatal heatstroke occurs 3.5 times more frequently in overweight or obese adults than those of average body weight, according to research published last year in the Canadian Medical Association Journal.