What is the Origin of Fat Mass Defense?

This concept is central to the field of adipobiology and energy homeostasis, recognizing that fat mass is not merely a passive energy store but an actively defended organ. The defense mechanism evolved to protect against starvation, a significant threat throughout human history. The "set point theory" of body weight is the theoretical foundation for this physiological resistance.

What is the Mechanism of Fat Mass Defense?

A reduction in fat mass leads to a decrease in the adipokine leptin, which normally signals satiety to the hypothalamus. This drop triggers a potent, compensatory increase in orexigenic (appetite-stimulating) hormones like ghrelin and neuropeptide Y. Simultaneously, the body reduces thermogenesis and basal metabolic rate, minimizing energy expenditure. These hormonal and metabolic shifts conspire to restore the previous, higher fat mass set point.

Fat Mass Defense ∞ Area

Fat Mass Defense

Meaning

Fat mass defense is the coordinated physiological and hormonal response by the body to resist changes in its established adipose tissue set point, particularly against weight loss. This adaptive homeostatic mechanism employs neuroendocrine counter-signals to increase hunger, decrease energy expenditure, and enhance metabolic efficiency. It is a powerful survival mechanism that frequently complicates sustained weight management.