Leptin-resistance - Many of the neuroendocrine alterations that occur during fasting for normal weight subjects or subjects who are leptin-deficient appear blunted in obese individuals. Since obese humans show elevated levels of leptin in serum and adipocytes, and show limited effects with leptin treatment, many researchers suggest obese humans exhibit leptin resistance similar to what happens with insulin resistance.

Damage to hypothalamus receptor as a result of high leptin levels caused by overfeeding - In addition to numerous theories including defects involved in the leptin transport system, it is suggested that overfeeding or overeating may stimulate an overabundance of leptin. This high level exposure results in the leptin system getting “overloaded” or disturbed leading to sustained defects.

False - Circulating ghrelin concentrations are negatively correlated with BMI in humans, and these levels increase when humans lose weight, and decrease when anorexic patients gain weight. This pattern suggest ghrelin levels change in response to dieting to maintain body weight.

False - Although leptin treatment has been shown to have beneficial effects in patients with leptin deficiency, it shows very limited effects in obese patients overall.

In obese subjects, circulating ghrelin levels are increased and leptin levels are decreased after weight loss as a result of lowered caloric intake. This process is thought to potentially signal the brain to increase hunger, leading to increase caloric consumption and weight regain