Long-term leptin treatment in lean mildly hypoleptinemic women led to 4–4.5% of body weight loss (exclusively fat mass), which is far less compared to the weight loss observed in CLD11, modestly less than the weight loss observed in severe hypoleptinemia due to GL (~5.5%)10, and significantly more compared to the neutral weight effects observed in hyperleptinemic obesity. This evidence concerns the gene LEP and obesity due to melanocortin 4 receptor deficiency.