Answer:
Overweight people have high level of leptin in their blood stream that does not keep in check their appetite, it is due to lack if sensitivity of their leptin binding receptor, it means that the receptor with which leptin is to bind and work effectively is not working properly due to which the hormone is not doing its function well and although found in the bloodstream at high levels. While in case of obese mice these receptors are working properly and upon dosage of leptin, abrupt loss in their weight was seen.