Americans still havebeen gaining weight,although they have cut their average fat intake from 36 to34 percent of their total diets in the past 15 years.Indeed,cutting fat to

control or loseweight makes sense. Fat has nine calories per gram. Protein and carbohydrates（碳水化合物）which break down into aminoacids and simple sugars

respectively,havejust four. Moreover,the body uses fewer calories to metabolize（新陈代谢）fat than it does to metabolizeother foods.

But cutting fat fromyour diet doesn't necessarily mean your body won't store fat. For example,between nonfat and regular cookies,there's trivial difference in calories

because manufacturersmake up for the loss of fat by adding sugar. Low-fat crackers,soups anddressings can also be just as high in calories as richer versions.No matter

where the caloriescome from,overeating will still cause weight gain.The calories from fat just doit a little quicker. A Wisconsin computerprogrammer who decided with a

diet coach to eatonly 40 grams of fat a day learned the lesson firsthand.He wasn't losingweight.Then he showed his food diary to his coach and revealed he'd been eatinghalf

a pound of jellybeans a day."They don't have any fat,"he explains.But they had enoughsugar to keep him from losing an ounce.

Nonfat foods becomeadd-on foods.When we add them to our diet,we actually increase the number ofcalories we eat per day and gain weight. That was born out in a

Pennsylvania State University study.For breakfast,Prof. Barbara Rolls gavetwo groups of women yogurt that contained exactly the same amount ofcalories.One group's

yogurt labelsaid"high fat”一theother,"low fat". The"low fat"yogurt group ate significantlymore calories later in the day than the other group. "People think they'vesaved fat

and can indulgethemselves later in the day with no adverse consequences,"says RichardMattes,a nutrition researcher at Purdue University."But whenthey do that,they don't

compensate veryprecisely,and they often end up overdoing it."

What lesson didthe computer programmer learn?

A.He shouldn't eatany sugar.

B.He should only eatnonfat food.

C.He shouldn't eatany food.

D.He shouldn't eattoo much.