Intermittent fasting not advised

Dear Dr. Roach: I read a recent headline that said people who fast intermittently have an increased risk of heart disease. Is there merit to this story?

K.O.S.

Answer: Intermittent fasting is an increasingly common weight-loss strategy. The two most common approaches of intermittent fasting are alternate-day fasting (eating nothing one day, then whatever you want the next) and time-restricted feeding (eating at certain times in the day, usually in an eight-hour time frame). The published data on the benefits of these diets show shortterm weight loss (i.e., 12 weeks), but no long-term weight loss (1 year), compared to standard dietary advice.

There is evidence of potential harm from intermittent fasting. Studies have shown an increased risk of eating disorders (particularly binge eating).

The concern for disordered eating is highest among younger and female populations, who are most at risk for eating disorders, and I advise against intermittent fasting for a person with a history of an eating disorder.

The study you read about was presented as an abstract in the March meeting of the American Heart Association. It showed that people who report an intermittentfasting diet (those who ate over an 8-hour time frame) were at a higher risk for death from heart disease than those who ate over a 12-16 hour time frame. However, this wasn’t a controlled study, and it is likely that people who chose a timerestricted eating pattern already had issues that put them at a higher risk for heart disease.

Still, given the absence of long-term benefits, I don’t generally recommend a time-restricted diet to my patients.

My colleagues in weight medicine consider intermittent fasting to be an option that helps a subset of people. There are some people who do benefit from this type of diet, and as long as they are eating well and are being monitored by their physician, they should continue to follow their diet if it is working for them.