Although the results from our study appear to contradict previous studies that concluded that weight loss increases β cell function in people with obesity without T2D (8, 18, 20, 32, 33), β cell function in those studies was evaluated by using the disposition index or other indices that assessed insulin secretion/insulin concentration in relation to insulin sensitivity (34, 35). This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.