The primary aim is to assess the tolerability and preliminary safety of subcutaneous recombinant-methionyl Leptin (r-metHuLeptin) as compared to placebo in subjects across a range of doses and body mass indexes. The secondary aims are to evaluate the pharmacokinetic profile of r- metHuLeptin; to assess effects of the drug on the metabolic profile of subjects by evaluating changes in fasting and stimulated glucose and insulin levels and in fasting lipid levels; and to assess the immunogenicity of the drug.