Intermittent Fasting: Is It for You?
Intermittent fasting is a practice in which a person establishes a limited number of hours in which to eat during the day and chooses not to eat during the remaining hours. In recent years, it’s become a popular way to lose weight. But is it healthy?
Erin Zepp, RD, CDE, a dietitian with the Memorial Weight Loss & Wellness Center, said that research into intermittent fasting, or IF, has shown some promising results. But it isn’t the right choice for everybody.
“At the end of the day, the key to losing weight and improving health lies in eating fewer calories than you burn, choosing nutrient-dense, whole foods whenever possible and exercising regularly,” she said. “IF may provide the framework that some people need in order to finally achieve the health goals they have been aiming for. But it is just one approach and is not suitable for everyone.”
Almost everyone routinely fasts every day without realizing it, in the interval between dinner and breakfast the next morning. For that reason, IF is nothing new. Many people following IF protocol will abstain from food for 16 hours per day and freely eat during the other eight hours. Other proponents of IF fast for longer—20-24 hours—for one or more days in a week or month.
Some studies of IF have shown it can result in improved blood lipids (triglycerides and LDL cholesterol), lower blood pressure, lower inflammation, more stable blood glucose levels and weight loss. However, these studies were mostly done on animals.
“As with almost all nutrition research, human studies are very limited and tend to be poorly balanced by control groups,” Zepp said. “That makes it really hard to point firmly in the direction of a human study and say ‘Yes! THIS is definitive!’”
She added that animal studies also fail to take into account the wide variety in the human diet, which makes it difficult to conclusively determine whether it’s the timing of meals—or the content—that leads to weight loss.
“Some people following the protocol report that IF helped them to finally conquer their hunger,” Zepp said. “They feel more in control when they fast for a portion of the day. It can be a valuable tool to help establish the difference between ‘head’ hunger, or psychological hunger, and ‘body’ hunger, or physiological hunger.”
But for others, fasting can go too far. For those with a history of anorexia or disordered eating, IF can become a way to mask very unhealthy patterns of food restriction as a socially acceptable “fast” in order to achieve greater health.
Zepp said that patients hoping to lose weight often come to the Memorial Weight Loss & Wellness Center with a habit of skipping breakfast and lunch. Those patients see weight-loss benefits once they start eating nutritious meals throughout the day. Although they are no longer spending as many hours fasting, an increase in nutrition and physical activity leads to better health.
“There is more to achieving optimal health than when a person chooses to eat,” Zepp said.