The body is  a finely tuned machine. So fine-tuned, in fact, that the difference between maintaining body weight and gaining one pound a year could be as little as a single potato chip per day.

Randy Seeley, professor of medicine and director of the Cincinnati Diabetes and Obesity Center, estimates that an adult man would need only 11 extra calories per day to gain a pound each year.

Let's do the math:

A typical adult male consumes 900,000 calories each year.

To gain just one pound each year, he would need to eat about 4,000 calories more than he burns.

4,000 calories divided by 365 days = approximately 11 extra calories per day, or about one potato chip.

"When you look at how obesity has affected our country," says Seeley, "and you realize that the average person — someone who may be considered overweight — is gaining less than one pound per year, it's easy to see how accurate our bodies are at matching our caloric intake to caloric expenditure. Relatively small mismatches over time are all that are necessary to gain weight."

So, yes, Seeley says, one chip really could matter, but he's quick to caution that his calculations don't take into account variability be-tween individuals and environmen-tal and genetic factors that contribute to weight-gain susceptibility.

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