In modestly obese adult women, macrophage infiltration and phenotypic switching in visceral adipose tissue are not significantly increased despite the presence of insulin resistance.

When fat cells in the belly grow larger due to modest weight gain, they become stressed and release chemical signals that disrupt insulin function in the body. These signals create a local inflammatory environment, but immune cells called macrophages do not yet move into the tissue or change their type. Instead, the fat cells themselves produce molecules that directly interfere with insulin signaling, while other immune signals remain quiet until later stages of metabolic decline.