What is the primary outcome of losing weight through diet only?

Losing weight through diet alone primarily leads to a reduction in body weight, which often comes with a decrease in both fat mass and lean body mass (LBM). While it is possible for some individuals to maintain LBM through careful dietary practices, it is common for dieting without accompanying physical activity or resistance training to result in some loss of muscle mass.

This option indicates that, although there might not be an explicit change in LBM, the primary outcome generally observed when weight loss is primarily through diet is that LBM can be better preserved with a well-structured diet as opposed to potentially losing more muscle. However, in many scenarios, especially with aggressive calorie restriction or inadequate protein intake, there may indeed be a reduction in LBM.

Other options reflect incorrect outcomes related to the complexities of weight loss. For instance, fat mass typically decreases with weight loss efforts focused on diet, while metabolic rate would generally tend to decrease as individuals lose weight without exercise. The enhancement of endurance performance typically requires not just weight loss but also a structured training program, ensuring that the individual’s energy and nutrient needs are adequately met.