GCG and obesity due to melanocortin 4 receptor deficiency: This combination of effects makes glucagon a very attractive anti-obesity treatment, as typically drugs which increase energy expenditure also cause an increase in food intake [75], [76], which means there is likely to be no overall loss of weight; and conversely, but equally problematically for an obesity treatment, reducing food intake is usually accompanied by a decrease in energy expenditure, with subsequent limits as to the weight which can be lost [77].