The carbohydrate-insulin model (CIM) suggests that high levels of dietary carbohydrates elevate insulin secretion, which suppresses fatty acid oxidation and the release of fatty acids from adipose tissue while promoting lipogenesis. This creates a state of cellular “internal starvation” that drives both increased food intake and decreased energy expenditure, leading to obesity. Hu et al. directly tested specific predictions of the CIM in a mouse model. They found that only the changes in the post-prandial insulin and fasting glucose followed the CIM’s predictions in relation to the dietary carbohydrate. Fasting insulin, energy intake, energy expenditure, and body fat mass did not follow the trends predicted by the CIM.