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Calorie-restriction may change protein levels: Study

By Stephen Daniells , 14-Dec-2009

Restricting calorie intake may lead to changes in the levels of certain proteins, says a new study that deepens our understanding of how low-cal diets may improve health.

A five-week-long calorie-restricted diet was found to produce changes in the levels of six proteins, including proteins that tell the body to store fat, in obese human volunteers, according to findings published in the Journal of Proteome Research.

“The worldwide increasing prevalence of obesity and its consequences for human health request novel ways of prevention and treatment,” explain the researchers, led by Edwin Mariman from Maastricht University in The Netherlands.

“A better insight in the underlying physiologic and molecular processes is therefore required,” they added.

According to their findings, five weeks of consuming a very low-calorie diet followed by three weeks of a normal diet resulted in changes in protein expression levels, as observed in the proteome, in fat cells (adipocytes).

“Additional studies can now be initiated to confirm and deepen the role of specific proteins and their molecular pathways indicated by the present results,” wrote the researchers.

Less is more

Calorie restriction, while avoiding malnutrition, has already been reported to extend lives and reduce the risk of chronic disease in certain species, including monkeys.

Scientists from the University of Wisconsin-Madison published findings in Science showing that 80 per cent of rhesus monkeys who consumed a calorie restricted diet were still alive after 20 years, compared to only 50 per cent of control animals who ate freely.

Certain compounds found in the diet may also activate Sirt1, with the most focus being on resveratrol, a polyphenol found in red wine. David Sinclair and his team from Harvard reported in Nature in 2003 that resveratrol increased the survival of yeast cells.

Study details

For the new study, Mariman and his co-workers recruited eight overweight and obese people to participate in their study. The subjects were required to consume a very low calorie diet, providing only 500 kcal per day (Modifast, Nutrition et Sante’, France) for five weeks. After this period they followed a normal diet for three weeks.

According to their findings, the subjects lost an average of 9.5 kg (21 lbs) of body weight, with fat loss the main contributor with 7.1 kg.

Using the proteomic technique, the scientists identified changes in the levels of six proteins as the volunteers shed pounds, including proteins that tell the body to store fat. The proteins could therefore become markers for monitoring or boosting the effectiveness of calorie-restricted diets, they say.

Source: Journal of Proteome Research
Volume 8, Number 12, Pages 5532-5540, doi: 10.1021/pr900606m
“The physiologic effects of caloric restriction are reflected in the in vivo adipocyte-enriched proteome of overweight/obese subjects”
Authors: F.G. Bouwman, M. Claessens, M.A. van Baak, J.-P. Noben, P. Wang, W.H. M. Saris, E.C.M. Mariman