What contributes the least to daily caloric needs?

The thermic effect of food (TEF) contributes the least to daily caloric needs compared to the other factors listed. TEF refers to the energy expended by the body in order to digest, absorb, and metabolize food. While this process does require energy, it typically accounts for only about 5-10% of total daily energy expenditure, which is significantly lower than the contributions of resting metabolism and physical activity.

Resting metabolism, also known as basal metabolic rate (BMR), accounts for the majority of daily caloric needs, often around 60-75%, as it reflects the energy required for essential bodily functions at rest. Physical activity can also vary widely but generally accounts for a significant portion of energy expenditure, depending on the individual's activity level. Lastly, body composition plays a crucial role in metabolism since muscle tissue burns more calories at rest compared to fat tissue, further emphasizing the larger contributions of resting metabolism and physical activity to overall caloric expenditure.

In summary, while the thermic effect of food does play a role in total energy expenditure, its impact is minimal when compared to the other elements, making it the correct choice for contributing the least to daily caloric needs.