Eating in a 6-hour window and fasting for 18 hours might help you live longer
A review of past animal and human studies in The New England Journal of Medicine suggests that intermittent fasting can reduce blood pressure, aid in weight loss and improve longevity.
Study author Mark Mattson, a professor of Neuroscience at Johns Hopkins University, hones in on two types: Daily time-restricted feeding (eating 6-8 hours a day and fasting for 16-18 hours) and 5:2 intermittent fasting (fasting two days a week, usually capping a fasting day at 500 calories).
Alternating between fasting and eating can improve cellular health, Mattson said, most likely by triggering metabolic switching. In metabolic switching, cells use up their fuel stores and convert fat to energy – “flipping a switch” from fat-storing to fat-saving.
Findings on intermittent fasting range in the diet’s effectiveness, but some studies in animals and humans have linked the practice to longer lives, healthier hearts and improved cognition.
The study has been conducted in rodents and overweight adults and found to improve health across the spectrum, though it’s not clear if those benefits are the result of weight loss.
Intermittent fasting is also thought to improve insulin resistance, which can stabilize blood sugar levels.
Findings from a 2018 study found that three men with type 2 diabetes, also known as adult-onset diabetes, were able to stop taking insulin after losing weight from intermittent fasting — findings that clash with the widely-held belief that diabetes is incurable.
The report functions as a road map of sorts for physicians to prescribe fasting as a method of prevention or treatment for obesity, cancer, diabetes and heart disease.
A previous study that Mattson co-authored showed the switch can increase resistance to stress by optimizing brain function and neuroplasticity, or the brain’s ability to adapt to develop throughout one’s life. And older adults who were put on a restricted-calorie diet showed improved verbal memory compared to two other groups who hadn’t fasted, a 2009 study found.
Physical function even improved for some patients. A study of young men who fasted every day for 16 hours lost fat and retained muscle while resistance training for two months.
However, he long-term effects of intermittent fasting require more research that isn’t available yet, and the studies that do exist are narrow. The clinical trials focused on overweight young and middle-age adults, so the benefits and safety can’t be generalized to other groups, the authors said.
More so, because the research is relatively new, the report advises physicians to monitor their patients throughout intermittent fasting and gradually increase the duration and frequency of fasting to guide their transition.