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Health

Hot, cold, heavy?

Some facets of modern life - from heating and air conditioning to the amount of sleep you get - can pack on the pounds.

By TOM VALEO
Published December 26, 2006

We live in a society that provides loads of cheap, tasty food, along with ingenious labor-saving devices that make human sweat seem almost quaint.

No wonder we're getting fat.

But modern life conspires in other ways to add extra pounds, according to a recent paper in the International Journal of Obesity, and some of those ways become bigger problems as we age.

For example, there is sleep - or rather, the lack of it.

Many studies suggest that people who sleep less tend to be heavier. One possible reason for this may be the way sleep deprivation lowers the level of leptin, the hormone that tells your brain your stomach is full, and increases your level of ghrelin, the hormone that tells you you're hungry.

In one study, the leptin levels in men who slept only four hours on two consecutive nights dropped 18 percent, and their ghrelin levels rose 28 percent. The men said they felt a lot hungrier than usual.

People in the United States now sleep an average of less than 7 hours a night, and getting restful sleep becomes more difficult with age. Obesity itself can cause sleep apnea, a breathing difficulty that disrupts sleep, and this problem contributes to weight gain.

Heating and air conditioning also may contribute to weight gain. Both shivering and sweating burn calories, but we do less of each when we live in a building with efficient climate control.

One study found that women in a respiration chamber kept at nearly 81 degrees burned about 239 calories a day more than women kept at 71.6 degrees. Also, higher temperatures tend to make people less hungry.

People tend to give up smoking as they get older, and quitting really does cause people to gain weight. Maybe nicotine suppresses appetite, scientists say, and maybe it revs up the metabolism, too.

Certain drugs also pack on pounds, especially drugs used to control epilepsy, high blood pressure, diabetes and mental problems.

Some evidence suggests that exposure to industrial pollution may cause weight gain. Mice given small amounts of dieldrin, a pesticide, more than doubled their amount of body fat, and rats given another pesticide gained weight even though they were given half as much food as normal.

Studies have also found that humans who eat fish containing PCBs tend to be heavier.

Women who have their first child later in life are at greater risk for obesity, and the age at which women in the United States have their first child has been rising steadily in recent decades.

Their children are at risk, too: The National Heart, Lung and Blood Institute has found that the odds of a child growing up to be obese increase about 14 percent for every five years added to the mother's age at the time the child was born.

The Web site CalorieLab Calorie Counter News said that information "is of very little practical use." Far more relevant, the site asserted, is that "There is now at least one major calorie-heavy fast food franchise within walking distance of 88 percent of the American public."

Freelancer Tom Valeo writes about medical and health issues. Write to him in care of Pulse, St. Petersburg Times, P.O. Box 1121, St. Petersburg, FL 33731, or e-mail features@sptimes.com

[Last modified December 26, 2006, 06:29:45]