Answer is Variable, as Seminoma stated, unless the question is strictly going by the definition of Obesity and not via BMI. Since they are comparing obese to a "normal BMI" I would say they are most likely talking in terms of BMI. A great way they could test you on this is using WTH ratio. WHO states that it is a measurement of obesity which is an efficient predictor of mortality. They can say something along the lines of "a patient has a high Waist-to-Hip Ratio" and then throw a Leptin question in the middle after which the answer would be: high leptin levels with a decreased appetite.
Leptin and BMI are directly proportional on a graph (unless they mention the patient is an avid bodybuilder).
Leptin acts on the Arcuate Nucleus of the Hypothalamus to decrease the production of Neuropeptide Y (a potent stimulator of appetite). It also stimulates the production of POMC. Alpha-MSH(increases satiety) is produced by cleavage of POMC, inhibiting food intake.
Thus a mutation in the Leptin gene or receptor will lead to Hyperphagia and profound Obestiy.