Lifestyle interventions such as diet and exercise result in only modest long-term weight loss (2–4% after 10 years) in individuals with obesity due to the persistence of biological adaptations that maintain a higher adipose mass set point.

When a person loses weight, their body responds by slowing metabolism, increasing hunger, and reducing fullness signals to force weight back up. This happens because fat cells produce less of a hormone called leptin after weight loss, and the brain no longer responds properly to leptin even when fat stores are large. The brain interprets this as starvation and triggers hunger, lowers energy use, and shifts the body to store fat instead of burning it. These changes persist long-term, making it nearly impossible to keep weight off without changing how the brain perceives fat levels.