For many people, the New Year is a time to adopt new habits as a renewed commitment to personal health. Trying new diets is one of them. But does scientific evidence support the claims for these diets? In a review article, Johns Hopkins Medicine neuroscientist Mark Mattson, Ph.D., concludes that intermittent fasting does.
Mattson, who has studied the health effects of intermittent fasting for 25 years and adopted it himself about 20 years ago, writes that “intermittent fasting can be part of a healthy lifestyle.”
Intermittent fasting diets, he says, generally fall into two categories:daily time-restricted eating, which shortens eating time to 6-8 hours per day, and so-called 5:2 intermittent fasting, in which people limit themselves to one moderate meal—two meals. days a week.
A series of animal studies and some human studies have shown that alternating fasting and eating supports cellular health, probably through an age-old adaptation to periods of food scarcity called metabolic switching. Such a switch occurs when cells use up their stores of rapidly accessible sugar-based fuel and begin to convert fat into energy in a slower metabolic process.
Mattson says studies have shown that this switch improves blood sugar control, increases resistance to stress and suppresses inflammation. Because most people eat three meals plus snacks every day, they don't experience the switch or the suggested benefits.
In the article, Mattson notes that the four studies in both animals and humans found that intermittent fasting also reduced blood pressure, blood lipid levels and resting heart rate.
There's also mounting evidence that intermittent fasting can alter risk factors for obesity and diabetes, Mattson says. Two studies at the University Hospital of South Manchester NHS Foundation Trust of 100 overweight women showed that those on the 5:2 intermittent fasting diet lost as much weight as women who restricted calories, but performed better in insulin sensitivity and reduced belly fat than those in the calorie-reducing group.
More recently, Mattson says, preliminary studies suggest that intermittent fasting may also benefit brain health. A multi-center clinical trial at the University of Toronto in April found that 220 healthy, non-obese adults who followed a calorie-restricted diet for two years showed signs of improved memory in a battery of cognitive tests. While much more research needs to be done to prove the effects of intermittent fasting on learning and memory, Mattson says if that evidence is found, the fasting — or a pharmaceutical equivalent that mimics it — could provide interventions that could prevent neurodegeneration and dementia. .
