Can fasting keep the holiday pounds off?

The average adult gains between 0.5 to 1.0^[1] kilograms per year. This can lead to weight accumulation and obesity over the course of many years. There has been some research that suggests that the majority of this weight gain occurs during the traditional holiday season between the months of November and December. For example, roughly 0.4 kilograms^[2] of weight gain have been observed between mid-November to early January. Another study showed a 0.6 kilogram^[3] increase during the weeklong period between Christmas and New Year’s Day. As you can see in Figure 1, this weight gain occurs roughly in the same time frame in both the U.S. and Germany, with Japan’s frame for weight gain shifted to after New Year’s Day. Furthermore, this holiday weight gain is not lost^[2] in the subsequent spring and summer months. As such, finding ways to mitigate holiday weight gain may be an important aspect of reducing weight gain in an individual’s life, and thus, reducing their overall risk of obesity.

One potential solution for the prevention of weight gain during the holiday period is the use of intermittent energy restriction (IER), defined as short periods of eating significantly below energy requirements, interspersed with regular eating periods. This differs from conventional energy restriction during which energy intake is chronically reduced below the amount normally consumed for long periods of time. One popular implementation of IER is known as the “5:2 diet.” This implementation is characterized by substantial caloric reductions for two days a week and normal intake for five days a week. On the two days of reduction, food can be reduced as low as zero to 500 calories per day. This approach has been shown to be an effective tool for weight loss in previous studies^[4].

The present study is a randomized controlled pilot trial designed to evaluate the effects of a modified 5:2 IER nutrition program to prevent weight gain in overweight healthy adults over the winter holiday period between Thanksgiving and New Year, compared with a control group following their habitual diet.

Much of the yearly weight gain that occurs in adults occurs during the holiday season. Intermittent energy restriction (IER) has been shown to aid weight loss in previous studies, yet it has not been investigated as a tool to prevent holiday weight gain. The present study is a randomized controlled pilot trial designed to evaluate the effects of an IER nutrition program to prevent weight gain in overweight healthy adults over the holiday period.