For many people, the New Year is a time to adopt new habits as a renewed commitment to personal health. Intermittent fasting is a trendy diet approach that claims to have weight loss and healthy benefits.
According to a review article published in The New England Journal of Medicine, scientific evidence does support the claims made for intermittent fasting does.
How does intermittent fasting work?
Intermittent fasting diets fall generally into two categories: daily time-restricted feeding, which narrows the eating window to a 6- to 8-hour period, and so-called 5:2 intermittent fasting, in which people fast five days a week and eat regular-sized meals the two days a week.
A number of animal experiments and some human studies have shown that alternating between times of fasting and eating supports cellular health, probably by triggering 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 converting fat into energy in a slower metabolic process.
Benefits to metabolic health
Studies have shown that this switch improves blood sugar regulation, increases resistance to stress and suppresses inflammation. Because most North Americans eat three meals plus snacks each day, they don’t not experience the switch, or the suggested benefits.
The review stated that four studies in both animals and people found intermittent fasting also decreased blood pressure, blood lipid (fat) levels and resting heart rates.
Evidence is also mounting that intermittent fasting can modify risk factors associated with obesity and diabetes.
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 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.
Possible brain benefits
More recently, preliminary studies suggest that intermittent fasting could benefit brain health too.
A multicenter clinical trial at the University of Toronto found that 220 healthy, nonobese adults who maintained a calorie-restricted diet for two years showed signs of improved memory in a battery of cognitive tests. However, far more research needs to be done to prove any effects of intermittent fasting on learning and memory.
Researchers do not fully understand the specific mechanisms of metabolic switching.
The author of the review, from Johns Hopkins University School of Medicine, believes that with guidance, most people can incorporate intermittent fasting into their lives. It takes some time for the body to adjust to intermittent fasting, and to get beyond initial hunger pangs and irritability that accompany it. He recommends that people gradually increase the duration and frequency of the fasting periods over the course of several months.
Source: New England Journal of Medicine, December 26, 2019.
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