High-Intensity Exercise Leads to Weight Gain Summary

Summary: Exercise is good for weight loss. However, high-intensity exercise may be counterproductive. This is because very high-intensity exercise may result in circadian rhythm disturbances and increased stress hormone levels, leading to a subsequent reduction in physical activity levels and a slowdown in metabolic rates.

 There is no doubt that exercise is good for health. It aids weight loss, enhances metabolic health, and has numerous other health benefits. Thus, most guidelines recommend 150-300 minutes of moderate-intensity exercise weekly.

When looking at various recommendations, it is vital to note that not only exercise duration matters but also intensity. Very low-intensity exercise may be insufficient. However, high-intensity exercise may be counterproductive.

In fact, researchers have longknown that extremely intensive exercise may be harmful to health. Just consider professional sportspeople. These people are not known to have high life expectancy due to overtraining.

Understanding that high-intensity exercise may be bad is also important. Since, many people start exercising by following the guidelines. However, over the years, they may become obsessed with various exercise forms, thus overdoing it.

New Study Shows That High-Intensity Exercise May Even Lead to Weight Gain

This new study aimed to explore the less-than-expected weight loss effects of exercise, hypothesizing that a decrease in non-exercise physical activity (NEPA) and non-exercise activity thermogenesis (NEAT) due to high exercise intensity might be responsible. Researchers categorized adult male C57BL/6 J mice into three groups: sedentary, moderate exercise, and vigorous exercise. The exercise groups participated in a 30-minute treadmill session. NEPA and body temperature (BT) were tracked using an implanted activity monitor for two days before and three days after the exercise session. Additionally, the synchrony between NEPA and BT was assessed, and plasma corticosterone levels were measured 6 and 24 hours post-exercise.

The study results revealed that only the mice in the vigorous exercise group significantly decreased NEPA and BT, which means reduced subsequent or overall physical activity due to perhaps fatigue and slowed metabolic rate as seen by reduced BT.

This reduction led to increased body weight the following day despite the mice not consuming more food. Furthermore, vigorous exercise caused a noticeable delay in the daily synchronization between NEPA and BT. Simply said, the study found that high-intensity exercise also disrupts the biological clock or circadian rhythm, reducing sleep quality and increasing stress. Thus, poor sleep and higher stress hormone levels further contributed to weight gain in these mice.

The Bottom Line

This study by no means suggests that people stop doing exercise. Exercise is surely good for weight loss and metabolic health. However, it warns against overdoing the exercise. It could also help people understand why they fail to experience weight loss despite exercising regularly. It appears that too much training is as bad as a complete lack of training.

Too much training causes stress, fatigue, and changes in the biological clock, which also means adverse hormonal changes. All this results in subsequent reduced physical activity, higher cortisol levels, and a slowdown in metabolic rate.

So, when exercising for weight loss and metabolic health, engage in moderate-intensity exercise. Further, remember that consistency is the key. One can expect far better results by exercising regularly. Additionally, try to mix different kinds of exercises, such as high intensity with resistance training, stretching, certain low-intensity physical activities like walking, and more.

Source:

Funabashi, D., Dobashi, S., Sameshima, K., Sagayama, H., Nishijima, T., & Matsui, T. (2023). Acute Vigorous Exercise Decreases Subsequent Non-Exercise Physical Activity and Body Temperature Linked to Weight Gain. Medicine & Science in Sports & Exercise, 10.1249/MSS.0000000000003487. https://doi.org/10.1249/MSS.0000000000003487