Caloric Restriction in non-obese people translates into less oxidative damage in muscle cells, according to a new study by scientists at Pennington Biomedical Research Center. As oxidative damage has been linked to aging, this could explain how limiting calorie intake without malnutrition extends life span.
Civitarese and colleagues found that indeed fewer calories can improve whole body metabolism in conjunction with an increase in SIRT1 gene expression in skeletal muscle. These results raise the possibility that SIRT1 may contribute to more efficient metabolism, less oxidative stress, and increase longevity in humans as it does in lower organism. (Credit: Image courtesy of Public Library of Science)
A calorie-restricted diet provides all the nutrients necessary for a healthy life but minimizes the energy (calories) supplied in the diet. This type of diet increases the life span of mice and delays the onset of age-related chronic diseases such as cancers, heart disease, and stroke in rodents. There are also hints that people who eat a calorie-restricted diet might live longer than those who overeat. In addition, calorie-restricted diets beneficially affect several biomarkers of aging, including decreased insulin sensitivity (a precursor to diabetes). But how might caloric restriction slow aging? A major factor in the age-related decline of bodily functions is the accumulation of “oxidative damage” in the body’s proteins, fats, and DNA. Oxidants–in particular, chemicals called “free radicals”–are produced when food is converted to energy by cellular structures called mitochondria. One theory for h ow caloric restriction slows aging is that it lowers free-radical production by inducing the formation of efficient mitochondria.
Civitarese and colleagues enrolled 36 healthy overweight but non-obese young people into their study. A third of them received 100% of their energy requirements in their diet; the caloric restriction (CR) group had their calorie intake reduced by 25%; and the caloric restriction plus exercise (CREX) group had their calorie intake reduced by 12.5% and their energy expenditure increased by 12.5%. The researchers found that a 25% caloric deficit for 6 months, achieved by diet alone or by diet plus exercise, decreased 24hr whole body energy expenditure (i.e. overall calories burned), which suggests improved mitochondrial function. Their analysis of genes involved in mitochondria formation indicated that CR and CREX both increased the number of mitochondria in muscle. Both interventions also reduced the amount of DNA damage–a marker of oxidative stress–in the participants’ muscles.
The researchers also examined gene expression in the study participants. In yeast, worms, and flies the activation of the Sir2 gene increases life span and regulates cellular metabolism. An important question is whether caloric restriction can regulate SIRT1 (the mammalian equivalent of Sir2) in humans. Civitarese and colleagues found that indeed fewer calories can improve whole body metabolism in conjunction with an increase in SIRT1 gene expression in skeletal muscle. These results raise the possibility that SIRT1 may contribute to more efficient metabolism, less oxidative stress, and increase longevity in humans as it does in lower organism.
The results suggest that even short-term caloric restriction can produce beneficial physiological changes leading to improved health. Whether caloric restriction and the associated health benefits can be sustained over longer term remains to be established in humans.
Citation: Civitarese AE, Carling S, Heilbronn LK, Hulver MH, Ukropcova B, et al. (2007) Calorie restriction increases muscle mitochondrial biogenesis in healthy humans. PLoS Med 4(3): e76. (http://dx.doi.org/10.1371/journal.pmed.0040076)
Note: This story has been adapted from a news release issued by Public Library of Science.
Biosingularity 
I have read a bit about these studies, there is a lot of interesting info. to support the lifestyle of few calories more life (i.e. The Longevity Diet by Dr. Spindler) – the important thing to remember is to have very nutrient rich foods because your body needs to be nourished (just not over stuffed). Lady Rose, , co-author Incredible Shrinking Ladies blog
Interesting site! I have a friend that is a bit obese, maybe I could tell him about it. Nice site anyways.
There’s a couple of issues here: 1. How accurate is the study, and the conclusions that it draws, and 2. there’s a fine balance between calorie reduction and starvation. As the post above mentions, it is critical to maintain nutrients in your diet irrespective of calorie intake.
this website has helped me alot
i knew something about it but not a lot of people believed me
now i can tell them about it.
I’ve always heard that you should never eat more food then you can hold in the cup of both hands. But does eating less also mean eating more frequently. It would be impossible for me to eat a small meal and then wait hours for the next meal, and what is considered eating less, it would be different for everybody. This is a very interesting topic. It has to be better then overeating which in the long term is very destructive to your body.