Alternate day fasting, also known as intermittent day fasting, is not a new thing. People fast for a variety of reasons, ranging from spiritual and religious to holistic. Many fasting diets exist, including the Leangains, the 5:2 Diet and the Eat Stop Eat, and this trend continues to gain popularity. Alluring promises like extra fat loss, muscle gains and a longer life span reel people in. Sticking to a diet day in and day out is hard. For some, it feels like the cycle never ends and they give up. Enter a form of intermittent fasting known as alternate day fasting. Think of it as a stop and go system. Have you ever heard the expression “If it sounds too good to be true, it probably is?” Let’s take a closer look at how the process works and examine a recent study on alternate day fasting and obesity.
Does it work when compared to restricted calorie diets?
Alternate day fasting switches between a 'normal' eating day and a day that restricts calories. The regular meal days consist of eating a moderate high fat diet. On restrictive days, those following the diet are allowed one meal with 500 calories. Staying hydrated is essential, of course, so water is always allowed.
Is eating 500 calories realistic for someone who is overweight or obese? This is where the latest clinical study comes into play. Very few studies on alternate fasting exist and this latest one is the first long-term study. Researchers took 100 healthy, obese individuals between the ages of 18 and 64. The study compared alternate day fasting to regular, calorie-controlled diets. Diet adherence and weight loss among the groups were the primary areas of focus. The study followed participants for one year and split them into three groups: alternate day fasting, calorie restricting, or standardized diet without modifications. The first six months of the trial focused on weight loss and the remaining six months focused on weight maintenance. Not surprisingly, people following the alternate fast day diet ate more on the normal days and less on the fast days. A diet of 500 calories is incredibly restrictive and challenging for most people to adhere to. It was easier for the daily calorie restricted group to meet their goals. The weight loss between the fasting and calorie restriction groups were very similar.
Bottom Line: No significant difference was found between alternate day fasting and daily calorie reductions. Fasting may work for some people, but for others it is challenging to adhere to this type of diet. Alternate day fasting does not have enough evidence to support its use as a primary weight loss method. Find a diet that you can turn into a lifelong healthy habit.
Written by: Tiffany Tanksley, Wellness Workdays Dietetic Intern
1. JAMA Internal Medicine
2. Washington Post