A person in a long-term state of positive energy balance will likely:

A person in a long-term state of positive energy balance is consuming more calories than they are expending through daily activities and bodily functions. This surplus of calories provides the body with excess energy, which can be used for various physiological processes, including the building and storage of body mass.

In this scenario, the excess energy will typically be converted into fat or muscle, depending on the individual's activity level, diet quality, and specific exercise regimen. For instance, those who engage in strength training alongside a high-protein diet may gain more muscle mass, while individuals who have a less active lifestyle may primarily gain fat. However, the overall outcome of a long-term positive energy balance is an increase in body mass.

Other choices reflect scenarios that are unlikely under a sustained positive energy balance, where the body would either lose mass, maintain its current mass, or experience no change. In contrast, a consistent intake of more calories than the body needs leads predictably to an increase in body mass, making it clear why gaining mass is the expected outcome in this context.