Why Your Immune System Sabotages Weight Loss in Obesity

A new study published in Nature has uncovered why losing weight can be so difficult for people with obesity. Researchers found that the immune system plays a key role in slowing down weight loss. Specifically, white blood cells called neutrophils help the body hold on to stored fat during times of metabolic stress.

This discovery could lead to fresh approaches in obesity treatment by targeting the mechanism that makes weight loss harder for some individuals.

Neutrophils, a type of immune cell, move into fatty tissue when the body faces stress, such as food deprivation. Once there, they release signalling molecules that slow the breakdown of fat. The goal is to preserve energy reserves, but this process also makes weight loss more challenging.

The study showed that these cells are especially active in visceral white fat—the unhealthy fat around organs that is hardest to lose. In obese individuals, the genes linked to this fat-protecting pathway are more active, reinforcing the body's resistance to shedding weight.

When researchers blocked this mechanism in mice, weight loss became more effective. The findings suggest that targeting neutrophil activity in fat tissue could be a promising strategy for future obesity treatments.

The study highlights a direct link between the immune system and fat retention in obesity. By understanding how neutrophils slow weight loss, scientists may develop therapies that help people lose weight more effectively. However, further research is needed before such treatments become available.