Here, a 151% increase in fasting plasma apoA-IV concentration was observed in healthy men with overweight or obesity after five days intake of a eucaloric high-fat (71E%), low-carbohydrate diet, whereas no changes were observed after 5 days intake of low-fat (14E%), high-carbohydrate diet (study 1; Figure 1A). The gene discussed is APOA4; the disease is obesity due to melanocortin 4 receptor deficiency.