As anyone who’s ever dieted knows, restricting what you eat every day can be monotonous, gruelling work. Enter intermittent fasting, a plan that essentially involves carefully monitoring what you consume on certain days and eating whatever you want on others.
While it might sound intimidating (the name itself doesn’t exactly scream “user-friendly”), intermittent fasting can be adapted for a variety of eating preferences, from regularly abstaining from food for 12-16 hours at a time to not eating once or twice a week.
A new study looking at one of these types of fasting suggests that the method works roughly as well for weight loss as traditional dieting does. That might sound like a bit of a bummer to some proponents of fasting such as study author and nutrition professor Krista Varady, whose previous research indicated that the plan might be faster, easier, and more effective than regular weight loss diets. (Varady even wrote a book about this particular fasting method, called “The Every-Other-Day Diet,” which she discloses in the most recent paper.)
But there are reasons to stay hopeful, too, especially if you’re someone who’s tried toughing it out on protein shakes and salads and still failed to see results. Plus, a growing body of research on fasting suggests that in addition to helping with weight loss, the method could have other beneficial health outcomes, such as potentially reducing the risk for certain cancers and even possibly prolonging life.
Those potential benefits haven’t gone unnoticed amongst engineers and CEOs in Silicon Valley, many of whom are sworn devotees of the diet. These folks include a Bay Area group of biohacking enthusiasts called WeFast, which meets weekly to collectively break their fasts with a hearty morning meal, and Facebook executive Dan Zigmond, who confines his eating to the narrow time slot of 9 a.m. to 5:30 p.m.
For the study, published this week in the Journal of the American Medical Association, researchers pitted people assigned to follow a traditional restricted-calorie diet (eating roughly 25% of their normal daily calories) against those who were told to fast every other day (eating 25% of their normal calories on fast days and 125% on the other days) for a year. A control group who didn’t follow any type of diet was also included. At the end of the year, people in the standard diet group and the fasting group lost similar amounts of weight compared with those who didn’t do any type of diet at all. They also came away with similar results in terms of heart rate and blood pressure.
Still, fasting isn’t fool-proof.
Like other diets, it might be tough to stick to. Roughly a third of the people assigned to both dieting groups dropped out before their year was up, compared with about a quarter of the people in the control or non-dieting group. Also, many of the people in the fasting group gradually appeared to slide into old dieting habits, meaning that by the end of the trial they were effectively doing regular calorie-restriction rather than alternate-day fasting.
Nevertheless, as the study is the largest and longest study of its kind, more research is likely needed before we reach any definitive conclusions about how well it works — or doesn’t. One important takeaway, though, may be that if you’ve struggled with conventional dieting, fasting may be a worthwhile alternative to explore.
“It will be of interest to examine what behavioural traits make alternate-day fasting more tolerable for some individuals than others,” the researchers write.
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