Some potential benefits of restricting calories
A sampling of research on potential benefits of short-term fasting or calorie restriction includes:
Surgery: In a 2010 study, a team of researchers including James R. Mitchell, of the Harvard School of Public Health, showed that kidney donors who ate 30 percent fewer calories for three days and then fasted entirely for one before surgery recovered faster than people who ate whatever they wanted before the procedure. These patients were healthy, and the study was small, so more research is needed to see whether calorie restrictions help other surgical patients.
Spinal cord injuries and strokes: Wolfram Tetzlaff, of the University of British Columbia, has shown that mice who fast every other day immediately after a spinal cord injury or stroke recover much more mobility than mice allowed to eat whatever they want. This approach appears to help only during the first few months after the injury, and does not help if the spinal cord has been completely severed, he said.
Cancer: Research in mice and early studies of people suggest that cancer patients may benefit from eating no food for at least two days before chemo and a full day afterward, said Valter Longo, of the University of Southern California. He has done case studies of 10 people, is currently testing the safety of fasting in 18 cancer patients, and will shortly begin testing its effectiveness in 42 more.
Weight loss: In one four-month study of intermittent fasting for weight loss, women who ate extremely low-calorie diets on alternate days lost the same amount of weight as those who followed a typical Mediterranean weight-loss diet. The research, led by Michelle Harvie at the Genesis Prevention Center at University Hospital in South Manchester, England, found that those who fasted also had lower levels of insulin in their blood; high levels are linked to diabetes and cancer risk.
Alzheimer’s disease: Mark Mattson, of the Laboratory of Neurosciences at the National Institute on Aging, has found that mice vulnerable to a rodent equivalent of Alzheimer’s are less likely to develop memory problems if they are fed at intervals, rather than allowed to eat as much as they would like.