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Diet: Why you can't do what you know you should

August 21, 2008 |  1:25 pm

Fish3 Even as people understand more about what they should eat to stay slim or lose weight, they don't do it. Proof of that is an annual state-by-state obesity report by CalorieLab. For the third year running, Mississippi takes the prize for the fattest state, with 31.6% of the population obese. Colorado is the slimmest -- only 18.4% of them are obese. California, which inched up 0.4% to 23.1% since 2007, still manged to drop in the national rankings from 36th fattest state to 41st. But it's not anything Californians did. Rather, the state dropped because people in a lot of other states got even fatter.

It's not a pretty picture, and the Department of Agriculture released a study this month that helps explain why it's so hard to eat right. Dietary knowledge is not enough, the report concludes.

What gets in the way of eating whole grains, fruits and vegetables, fish, modest amounts of low-fat chicken and meat is not lack of information. It is, well ... life.

Using data from federal food surveys, researchers found that stress and hunger get in the way of good dietary habits. On a 2,000-calorie-per-day diet, people who wait five hours between meals compared with four hours will eat 52 more calories in that next meal. If they hold off another hour and wait six hours between meals, they'll gobble up an additional 91 calories. And, researchers found, they'll make less-healthy food choices when they do eat.

Where they eat makes a difference. People who eat at a restaurant eat an average of 107 more calories per meal than if they had eaten at home.

Using work hours as a proxy for stress, researchers found that people who work longer hours wait longer between meals, and eat more calories. People who work consume more calories than those who stay home, and the more they work, the more they eat.

"At four hours between meals, an individual who works 40 a week is estimated to eat about 20% more calories than someone who is not employed. At eight hours between meals, the calorie discrepancy jumps to nearly 40%," according to the report.

Knowledge does make some difference, however. A person who scored 50 on the USDA's Diet and Health Knowledge Survey will eat 28% more calories when eating away from home. A person with a score of 100 will eat only 12% more.

-- Susan Brink

Photo: Gordon M. Grant/Bloomberg News