Endurance exercise transforms fat tissue and improves metabolic health in adults with obesity

A new study published in Nature Metabolism reveals that long-term endurance exercise leads to significant improvements in abdominal subcutaneous adipose tissue (aSAT) in individuals living with obesity. The study, conducted in the United States, aimed to isolate the benefits of exercise from weight loss, showing how regular physical activity improves cardiometabolic health.

The research found that those who exercised regularly had higher capillary density, fewer pro-inflammatory macrophages, and increased levels of proteins involved in angiogenesis, mitochondrial function, and fat storage. These changes suggest improved fat metabolism and enhanced overall metabolic health.

Notably, the study identified upregulation of oxidative phosphorylation and thermogenesis pathways, which increase energy metabolism in aSAT, providing a clearer picture of how regular exercise enhances metabolic function in people with obesity.

Background

In individuals with obesity, dysfunctional aSAT can contribute to insulin resistance and other metabolic problems. Issues such as reduced capillaries and increased inflammation in aSAT are linked to poor fat storage and the circulation of excess fatty acids, which can worsen metabolic health. By improving aSAT, particularly through enhanced fat storage and reduced inflammation, exercise could offer protective benefits.

This study aimed to fill the gap in understanding how long-term exercise affects aSAT, independent of weight loss, to explore how physical activity can improve cardiometabolic outcomes.

Study Overview

The researchers recruited 52 adults living with overweight or obesity. Participants were divided into exercisers and sedentary individuals based on their activity levels. The exercisers had consistently engaged in moderate to vigorous aerobic activity for over two years.

Key measures included body composition, fitness levels, and metabolic health markers. Fresh aSAT samples were collected to analyse structural and molecular differences between the groups.

Key Findings

Exercisers demonstrated significantly higher aerobic fitness and reported tenfold greater physical activity. They also had lower insulin resistance and higher HDL cholesterol levels compared to the sedentary group.

In terms of aSAT characteristics, exercisers had higher capillary density and increased levels of mitochondrial and ribosomal proteins, indicating better fat metabolism and energy production. Inflammatory markers were reduced, and proteins linked to metabolic dysfunction were lower in exercisers, suggesting improved tissue health.

Proteomic analysis identified 158 differentially expressed proteins, showing enhanced metabolic pathways in exercisers. These included the activation of the AMPK signalling pathway, essential for mitochondrial biogenesis and fat metabolism.

Conclusion

The study demonstrates that long-term endurance exercise leads to beneficial changes in fat tissue, boosting energy metabolism and improving cardiometabolic health in individuals with obesity. While short-term exercise offers some benefits, sustained physical activity is crucial for significant improvements in fat tissue function and overall health.