In people that do develop the typical "complications" associated with obesity weight loss has profound therapeutic effects. Currently, there are three distinctly different types of diets that have demonstrated considerable benefits in improving cardiometabolic health in both lean and obese people: 1) a Mediterranean diet, 2) a low-carbohydrate, ketogenic diet, and 3) a plant-based, very-low-fat diet. However, there is considerable inter-individual variability in body weight loss among people in response to any given diet, and it is not known why some people lose more weight with one diet than another. The mechanisms responsible for the different weight and metabolic responses to specific types of diets and the independent effects of weight loss and dietary macronutrient composition on cardiometabolic health are unclear.