What to do when you’ve gone on a binge

One of the problems with a high-fat diet is that the fat you eat is more easily stored by your body as fat. Research studies have found that the human body will fairly quickly increase the rate it burns carbohydrates as fuel when the person overeats carbohydrates. Overeating fat, on the other hand, appears to cause a similar adjustment to the body's fat burning, but that change seems to take place much more slowly.

What that means, practically speaking, is that a binge of high-fat foods like you might see over the holidays will cause what the scientists term a "positive fat balance" for several days after the binge, before the body starts to burn the excess fat more quickly. And unless those excess calories get burned off, you know what happens: long term weight gain. Scientists with the University of Wisconsin, in a recent article in The American Journal of Clinical Nutrition (2007;85:109-16), wondered if low to moderate intensity exercise might not help speed the body's adjustment to higher fat burning and designed a study to find out.

Ten women were recruited to participate in the study who were between the ages of 18 and 39, not obese (BMI between 20 and 30), otherwise healthy, and having a fairly sedentary lifestyle of less than 3 hours per week of low to moderate intensity exercise. For four days before the inpatient part of the study, the women were provided a low fat diet (30% of calories from fat) which was designed to maintain their weight. They were also instructed not to exercise for those four days.

Four days were then spent as inpatients in a special room designed to measure the amount of calories burned by the single human living inside. While inpatients, each subject was fed a high-fat diet (50% of calories from fat) that again was designed to maintain their weight, even though twice per day the subjects exercised on a stationary bicycle until they burned 150 or 300 calories, as randomly assigned by the study. Several times per day the subject's urine was tested to measure the amount of nitrogen in the urine, an indicator of the amount of fat the body is burning. As the researchers suspected, the low intensity exercise increased the rate of fat burning when the women switched to a high fat diet - and that more exercise caused an even higher rate of fat burning.

What this means for you

Regular exercise is critical for good health. A healthy diet is just as important. Still, the holidays come around or birthdays or other special occasions, and we go a little crazy at the buffet table or can't say no to a second piece of cheesecake. What do you do? Get back to your regular, healthy way of eating and get a little extra exercise - say, an extra 30 minutes' walking twice a day - for the following day or two to help your body's metabolism kick into gear to burn off the excess fat you've eaten.

First posted: January 16, 2007