Exercise Reverses Damage from A High-Fat Meal

So, you've just polished off a meal high in fat, and now you're feeling guilty? Wait an hour or two, then get a little exercise, and you can reverse the potential damage to your arteries, a new study suggests.

And you don't even have to head to the gym for that exercise. "We're talking about a walk, we're not talking about changing your clothes and sweating," said Janet P. Wallace, a professor of kinesiology at Indiana University, and lead investigator for the study.

Background

According to Wallace, after a fatty meal, arteries lose their ability to expand in response to an increase in blood flow. The effect peaks four to six hours after eating-usually just in time for your next meal. So, four hours after a fatty meal, your arteries look like those of a person with heart disease, she said.

"That post-meal period is a hot topic among all the researchers in heart disease, diabetes and obesity," Wallace said. "That period sets up the environment for the artery to be unhealthy."

The Study

Wallace and her colleagues studied eight healthy 25-year-olds. Each of the participants—five men and three women—completed three scenarios. They ate a low-fat breakfast, a high-fat breakfast and a high-fat breakfast followed two hours later by a 45-minute walk on a treadmill at a moderate pace. Each meal totaled 940 calories and the high-fat meal contained about 48 grams of fat and the low-fat meal actually contained no fat.

The researchers used a blood pressure cuff to measure blood flow in the brachial artery, the major blood vessel of the upper arm, before and after each scenario.

Results

"The brachial artery represents what is going on in the arteries of the heart," Wallace said. "The ideal range is about 6% to 10%," she said.

After the high-fat meal alone, the brachial artery dilation dropped from 6% to 4%, Wallace said. "A range of 3% to 5% is not good."

After the low-fat meal, dilation went from 6% to 6.5%, a slight improvement. After the high-fat meal and exercise, it went from 6% (before the meal) to 8.5%.

"Exercise does great things, and this obviously shows exercise is very effective in counteracting that high-fat meal," Wallace added.

More Research

Next, Wallace hopes to study the effect of exercise before a high-fat meal. "I think we will find it works as well." She emphasized that her research isn't meant to encourage people to indulge in high-fat fare. But she's realistic. "There are people who are going to eat high-fat meals," she said.

Jeannie Moloo, a Sacramento, California, registered dietitian and a spokeswoman for the American Dietetic Association, offered a caveat about the study. "We need to keep in mind the results apply only to the population investigated and that was young, healthy and physically active adults. The small number of subjects, only eight, makes it difficult to tell if there are differences in responses between men and women."

Exercise Controls Triglyceride Levels

Eating high-fat foods, such as whipped cream and chocolate, causes triglyceride levels to spike, increasing heart disease risk.

Recent study: Triglyceride levels of all participants who ate high-fat foods rose, but the levels of those who exercised for 90 minutes before eating were 25% lower than the levels of non-exercisers.