Intense Exercise Might Lead to Weight Gain, Animal Study Finds

University of Tsukuba research reveals potential downsides of high-intensity workouts**

Exercise is widely recommended as a key strategy for weight loss. However, a recent study from the University of Tsukuba , Japan has uncovered surprising findings: intense exercise can decrease subsequent physical activity and body temperature, potentially contributing to weight gain. This discovery, made through research on mice, suggests that the disruption of the circadian rhythm of the stress hormone corticosterone plays a significant role.

Key Findings:

- Intense exercise reduces subsequent physical activity and body temperature in mice.

- The stress hormone corticosterone’s circadian rhythm disruption is linked to this effect.

- Despite no change in food intake, reduced activity post-exercise can lead to weight gain.

Research Details:

Conducted by Daisuke Funabashi and colleagues, the study divided mice into three groups: high-intensity exercise, moderate-intensity exercise, and rest. They monitored the physical activity and core body temperature of the mice before and after exercise. The results were clear: in the high-intensity exercise group, both physical activity and core body temperature significantly decreased post-exercise, leading to weight gain despite no changes in food intake.

The stress hormone corticosterone, which typically peaks upon waking and is low at bedtime, regulates physical and mental activity levels. The researchers hypothesized that high-intensity exercise disrupts this rhythm, resulting in reduced physical activity and heat production. Indeed, they found a positive correlation between low blood corticosterone levels during wake times and decreased physical activity.

These findings suggest that a single session of high-intensity exercise can disrupt the circadian rhythm of corticosterone, leading to reduced physical activity and body temperature, ultimately contributing to weight gain.

Implications for Weight Loss Strategies:

This research highlights the importance of considering not only the calories burned during exercise but also the subsequent activity levels and circadian rhythm when designing exercise regimens for effective weight loss.

Contradictory Research: Moderate Exercise Enhances Overall Activity

While the University of Tsukuba study presents intriguing findings, other research indicates different outcomes for varying exercise intensities. For example, a study published in the *Journal of Applied Physiology* found that moderate exercise can enhance overall physical activity levels and improve metabolic health without disrupting the circadian rhythm.

This research divided participants into three groups: sedentary, moderate exercise, and high-intensity exercise. Unlike the Tsukuba study, this research observed that moderate exercise increased non-exercise physical activity (NEPA) and did not negatively impact body temperature or corticosterone levels. Participants in the moderate exercise group exhibited more sustained physical activity throughout the day, suggesting that moderate-intensity workouts might be more beneficial for long-term weight management.

The conflicting results between these studies underscore the complexity of exercise physiology and the need for personalized exercise plans. While intense exercise might disrupt circadian rhythms and reduce overall activity levels, moderate exercise could enhance overall physical activity and metabolic health.

Sources:

- University of Tsukuba

- Journal of Applied Physiology

About the Research

- Author: Daisuke Funabashi

- Source: University of Tsukuba

- Original Research: "Acute Vigorous Exercise Decreases Subsequent Non-Exercise Physical Activity and Body Temperature Linked to Weight Gain"

- Journal: Medicine & Science in Sports & Exercise