A new mouse study suggests fasting every other day can help fend off diabetes and protect brain neurons as well as or better than either vigorous exercise or caloric restriction.
The findings also suggest that cutting down on the number of meals eaten daily can also be beneficial even if the animals gorged when they did eat, according to investigators at the National Institute on Aging (NIA).
"The implication of the new findings on the beneficial effects of regular fasting in laboratory animals is that their health may actually improve if the frequency of their meals is reduced," said Dr Mark Mattson, chief of the NIA's Laboratory of Neurosciences. He added that the finding needs to be explored further to gauge the full impact that meal-skipping may have on health.
In the study, published in the Proceedings of the National Academy of Sciences Online Early Edition, Mattson and his colleagues found mice that fasted every other day but were allowed to eat unlimited amounts on intervening days had lower blood glucose and insulin levels than either a control group, which was allowed to feed freely, or a calorically restricted group, which was fed 30 per cent fewer calories daily than the control group.
Despite fasting, the meal-skipping mice tended to gorge when provided food so they did not eat fewer calories than the control group. This finding in mice suggests that meal-skipping improves glucose metabolism and may provide protection against diabetes, Dr Mattson said.
In the same study, mice on these three diets were given a neurotoxin called kainate, which damages nerve cells in a brain region called the hippocampus that is critical for learning and memory. (In humans, nerve cells in the hippocampus are destroyed by Alzheimer's disease). Dr Mattson's team found that nerve cells of the meal-skipping mice were more resistant to neurotoxin injury or death than nerve cells of the mice on either of the other diets.
Previous studies by Dr Mattson and his colleagues suggested that nerve cells in the brains of rodents on a meal-skipping diet are more resistant to dysfunction and death in experimental models of stroke and other neurological disorders including Parkinson's, Alzheimer's and Huntington's diseases. Dr Mattson also has found that meal-skipping diets can stimulate brain cells in mice to produce a protein called brain-derived neurotrophic factor (BDNF) that promotes the survival and growth of nerve cells.
The researchers are currently studying the effects of meal-skipping on the cardiovascular system in laboratory rats. The study compares the resting blood pressures and heart rates of rats that were fasted every other day for six months with rats allowed to eat unlimited amounts of food daily. Results are expected soon.