We do not anticipate that the response to the ketogenic meal could be amplified or further reduced in subjects with obesity, metabolic syndrome, or type 2 diabetes, but after a Mediterranean meal, we can imagine an increased insulin secretion in insulin-resistant subjects and the opposite in subjects with insulin secretory defects, both situations potentially leading to hyperglycemia. This evidence concerns the gene INS and obesity due to melanocortin 4 receptor deficiency.