What hormonal regulation is primarily affected by changes in body weight?

Insulin plays a crucial role in regulating blood glucose levels and is directly influenced by changes in body weight. As body weight increases, especially with an increase in adipose tissue, the body often experiences insulin resistance. This means that despite the presence of insulin, the cells do not respond effectively, leading to higher levels of glucose in the bloodstream and ultimately impacting metabolic processes.

In contrast, the other hormones listed, although they may also be affected by body weight changes in different ways, do not have the same direct and profound relationship as insulin. Thyroid hormones can influence metabolism and energy expenditure but are more regulated by other factors such as thyroid function itself rather than body weight alone. Adrenaline, or epinephrine, is involved in short-term stress responses and does not have a primary role in long-term regulation based on body weight. Estrogen levels can be influenced by body fat composition, but the primary regulation mechanism does not hinge on changes in body weight like insulin does.

Thus, insulin is the hormone most significantly and directly affected by changes in body weight, demonstrating a fundamental link between obesity and diabetes in metabolic health.