Intermittent fasting has gained some attention over the past few years as a method for optimizing health and losing weight. I wrote about the basics of fasting last year here; exploring the impact on metabolism and defining fasting.
I’m returning to this topic because a recent study shows some very promising results using fasting for weight loss. This study adds further support to the idea that having some limits on when we eat promotes health (here’s a more general review of this idea).
What They Did
Time-restricted feeding is a version of intermittent fasting where the “feeding window” (I know, it makes it sound like you are being fed like a lab rat!) is narrower by several hours. In this study, twenty-three obese adults followed an eight hour (10am-6pm) eating schedule for 12 weeks. During this time they could eat however they wanted but could only consume water or calorie-free drinks during the remaining 16 hours.
What They Found
Participants ate 340 fewer calories per day compared to their normal diet, lost 3% of their body weight (6 pounds) and improved their blood pressure by 7 points. The weight loss was modest which is likely a result of the freedom to eat however participants wanted. A key question for any weight loss approach is sustainability. Can people stick to the diet and what happens when they stop following the plan? This was not a focus of this research but is an important consideration if you are considering intermittent fasting.
What This Means for You
Restricting eating to 8 hours a day is dramatically different from how most of us consume food- in the study group, the average eating time was 11 hours before starting the restricted eating plan. A key advantages of this type of plan is the very clear boundaries around eating, which tends to reduce the number of calories consumed without having to track what you eat. In fact, a novel finding in this study is successful weight loss without specifically restricting calories or types of foods. Usually, weight loss requires changing how you eat, but in this study changing when you eat was the key. Another possible benefit has to do with resting the gut. Other research indicates that the intestines, like the brain, benefit from an extended rest period to heal and regenerate cells.
Interested in trying it out? Here’s a simple way to follow a daily time-restricted eating plan: Eat your first meal 1 1/2 hours later and your last meal 1 1/2 hours earlier than your normally do. This will usually mean you eat over an 8-10 hour period. We don’t know how narrow the feeding window needs to be, but most research points to 8-10 hours as beneficial.