Warning: do not read this article if you are about to go on holidays

How long do you think it takes before a high-fat diet begins impacting on our health? A year? Six months?

How about five days!

New research has found that after just five days of eating a high-fat diet, the way in which the body’s muscle processes nutrients changes, which could lead to long-term problems such as weight gain, obesity and other health issues.

“Most people think they can indulge in high-fat foods for a few days and get away with it,” said Matt Hulver, an associate professor of human nutrition, foods and exercise in the Virginia Tech College of Agriculture and Life Sciences. “But all it takes is five days for your body’s muscle to start to protest.”

When food is eaten, the level of glucose in the blood rises. The body’s muscle is a major clearinghouse for this glucose. It may break it down for energy or it can store it for later use. Since muscle makes up about 30% of our body weight and it is such an important site for glucose metabolism, if normal metabolism is altered, it can have dire consequences on the rest of the body and can lead to health issues.

Hulver and his colleagues found that muscles’ ability to oxidise glucose after a meal is disrupted after five days of eating a high-fat diet, which could lead to the body’s inability to respond to insulin, a risk factor for the development of diabetes and other diseases.

To conduct the study, healthy college-age students were fed a fat-laden diet that included sausage, biscuits, macaroni and cheese, and food loaded with butter to increase the percentage of their daily fat intake from normal levels of around 30% to about 55% fat. Their overall kilojoule intake remained the same as it was prior to the high-fat diet. Muscle samples were then collected to see how it metabolised glucose.

Although the study showed the manner in which the muscle metabolised glucose was altered, the students did not gain weight or have any signs of insulin resistance. Hulver and the team are now interested in examining how these short-term changes in the muscle can adversely affect the body in the long run and how quickly these changes in the muscle can be reversed once someone returns to a low-fat diet.

The results of the study were published in the online version of the journal Obesity.