Intermittent fasting may provide numerous health benefits like controlling blood-sugar levels, according to a review of studies which suggests the practice may help physicians guide patients towards a better lifestyle. The study's author, neuroscientist Mark Mattson from Johns Hopkins University in the US, said intermittent fasting diets generally fall into two categories -- daily time-restricted feeding, and the so-called 5:2 intermittent fasting.
The first kind Mattson said narrows eating times to 6-8 hours per day, and in the 5:2 fasting, he added that people limit themselves to one moderate-sized meal two days each week.
According to the review of studies, published in the New England Journal of Medicine, alternating between times of fasting and eating supports the health of the body's cells. Mattson said this probably happens by triggering an age-old adaptation called metabolic switching in which cells are tuned to periods of food scarcity.
The researchers said such a switch occurs when cells use up their stores of rapidly accessible, sugar-based fuel, and begin converting fat into energy in a slower metabolic process.
According to Mattson, the metabolic switch improves blood sugar regulation, increases resistance to stress, and suppresses inflammation. Mattson also found four studies in both animals and people where intermittent fasting also decreased blood pressure, blood lipid levels, and resting heart rates.
Since many people around the world eat three meals plus snacks each day, they may not experience the switch, or the suggested benefits, the neuroscientist said.
According to two studies which each assessed 100 overweight women, those on the 5:2 intermittent fasting diet lost the same amount of weight as women who restricted calories, but did better on measures of insulin sensitivity and reduced belly fat than those in the calorie-reduction group.
Another study at the University of Toronto found that 220 healthy, non-obese adults who maintained a calorie restricted diet for two years showed signs of improved memory in a wide range of cognitive tests.
With more studies on the effects of intermittent fasting, Mattson said the practice -- or a pharmaceutical equivalent that mimics it -- may lead to interventions that can stave off degeneration of nerves seen in conditions like Alzheimer's and dementia.
"We are at a transition point where we could soon consider adding information about intermittent fasting to medical school curricula alongside standard advice about healthy diets and exercise," Mattson said.