Final answer:
A client's estimated energy needs should be based on a combination of their basal metabolic rate (BMR), physical activity level, and body composition, with the BMR being a critical underlying factor.
Step-by-step explanation:
When determining a client's estimated energy needs, it's important to consider a variety of factors that contribute to the overall metabolic rate. A client's estimated energy needs should be based on their basal metabolic rate (BMR), which is the energy released when the subject is at complete mental and physical rest in a comfortable environment. The BMR accounts for a significant portion of an individual's energy expenditure, comprising approximately 70 to 75 percent of daily energy usage. However, for a comprehensive understanding of energy requirements, one also needs to factor in additional elements such as physical activity level and body composition.
Body composition is crucial because muscle mass burns more calories at rest compared to body fat, and therefore individuals with more lean muscle mass will have a higher BMR. Thus, while BMR is a foundational measurement, comprehensive energy needs should reflect all contributing factors, including lifestyle and physiological characteristics.