Junk foods start to impact metabolism after just five days, warn researchers

By Nathan Gray

- Last updated on GMT

Junk foods start to impact metabolism after just five days, warn researchers

Related tags Nutrition

Just five days of eating extra amounts of fatty foods can cause long-lasting metabolic changes that alter how muscles process nutrients, new research has found.

Many are aware of the risks associated with consuming a diet high in ‘junk foods’ and unhealthy fats over a long period of time – such as increasing weight gain, and a higher risk of obesity, diabetes and heart disease. But now researchers have suggested that even a short-term splurge could have a much more long-term negative impact on metabolism.

“Most people think they can indulge in high-fat foods for a few days and get away with it,”​ said study author Dr Matt Hulver, from Virginia Tech College of Agriculture and Life Sciences. “But all it takes is five days for your body’s muscle to start to protest.”

Indeed, while many may think it possible to ‘binge’ on unhealthy foods that are packed with high levels of fats without it making any significant changes, the new research published in Obesity reports that the way in which the body’s muscle processes nutrients changes after just five days eating a high-fat diet.

“This shows that our bodies are can respond dramatically to changes in diet in a shorter time frame than we have previously thought,”​ said Hulver.

“If you think about it, five days is a very short time,”​ he said. “There are plenty of times when we all eat fatty foods for a few days, be it the holidays, vacations, or other celebrations. But this research sho​ws that those high-fat diets can change a person’s normal metabolism in a very short timeframe.”

Study details

Hulver and his team recruited 12 healthy college-age men, who were split in to two separate study groups to study the effect of a short-term high-fat diet (HFD) on skeletal muscle and insulin sensitivity – including metabolic and transcriptional responses in skeletal muscle to the transition from a fasted to fed state.

All 12 participants 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. While a normal diet is made up of about 30% fat, study participants were fed a diet that contained about 55% fat, but contained the same amount of calories as they consumed before starting the diet, said the team.

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

While the study showed that the manner in which the muscle metabolised glucose was altered, participants did not gain weight or have any signs of insulin resistance, the authors added.

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 deleterious changes in the muscle can be reversed once someone returns to a low-fat diet.

The research was sponsored by the ​American Diabetes Association and the National Institutes of Health.

Source: Obesity
Volume 23, Issue 4, pages 720–724, doi: 10.1002/oby.21031
“Early skeletal muscle adaptations to short-term high-fat diet in humans before changes in insulin sensitivity”
Authors: Angela S. Anderson, et al

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1 comment

Johan Schoeman


High Fat Diet! Please define what you mean by fat as there are a variety of fats and trans fats as found in junk food in particular is very bad. However high levels of animal fat does not cause the same response as reported in the study.

I suggest that the scientists in this study familiarize themself with the work done by Dr. Tim Noakes in South Africa.

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