JAMA study: Does the 7am to 3pm time-restricted diet help with weight loss?

In recent years, there has been a wave of 168-hour fasting or 52-hour fasting methods in Taiwan, claiming that they can effectively reduce weight. A study in the Journal of the American Medical Association Internal Medicine pointed out that "early time-restricted eating" (eTRE), which limits eating to 8 hours between 7 a.m. and 3 p.m., can effectively reduce weight compared to eating within 12 hours or longer. However, when foreign media reported this study, they extended the explanation to say that "intermittent fasting" is related to longevity and reduced risk of age-related diseases, and downplayed the limitations of this study and "earlier time-restricted eating (eTRE)".

A study in JAMA Internal Medicine found that "early time-restricted eating" (eTRE), which restricts eating to an eight-hour period between 7 a.m. and 3 p.m., was more effective in reducing weight than eating over a 12-hour or longer period.

From the research point of view, the earlier time-restricted eating method has benefits, but it also has its limitations. The Taiwan Science and Technology Media Center stated that no one diet weight loss plan can be effective for everyone. While some people may be able to achieve weight loss with eTRE, others may not. We specially invited experts in the field of health nutrition and sports nutrition to share their views on this research.

What do the experts say?

Professor Jian Yiwen, Department of Health and Nutrition, Taipei Medical University

Jian Yiwen said that intermittent fasting has been a very popular method of weight control in recent years, which achieves the effect of weight loss by restricting food intake at different times. The most common ones are 168 fasting and 52 fasting. This study used "early time-restricted eating" (eTRE), which restricted eating to an 8-hour period between 7 a.m. and 3 p.m. The results showed that the eTRE group had better weight loss, diastolic blood pressure and mood improvements than the control group. Jian Yiwen explained that the study actually controlled the time of eating and compared it with the normal eating time. Even under the same conditions of controlling calories and exercise, there were still differences in the results of weight loss. The importance lies in the fact that there is empirical evidence to show the effect of fasting on the body's energy metabolism.

However, Jian Yiwen reminded that the weight loss effect focuses on changes in body composition. In this study, the eTRE group lost an additional 2.3 kg compared to the control group, but there was no significant difference in the reduction of body fat. Therefore, the inference that the eTRE group is more effective in weight loss may be somewhat limited, because the weight lost may be water or muscle weight, which is not recommended for health promotion.

Taiwan Science and Technology Media Center said that no one diet plan can be effective for everyone.

Hou Jianwen, professor at the Institute of Sports Science, Taipei City University

Hou Jianwen said that obesity is a very important factor affecting health. Studies have found that intermittent fasting in the short term can reduce weight or body fat and improve metabolic capacity better than calorie restriction. The main purpose of this study is to explore whether "early time-restricted eating" (eTRE, eating time 07:00-15:00) can have better effects on weight loss and health-related indicators under the condition of calorie restriction.

Hou Jianwen explained that the focus of this study is to reduce the time of eating throughout the day and try to finish the day's food in the first half of the day, which is somewhat similar to the concept of not eating after noon. When you are not exercising, it is recommended that you follow this diet principle, but if you exercise in the afternoon or evening, you need to change this principle and be sure to eat easily digestible food after exercise.

Taiwan Science and Technology Media Center