Primary factors that determine an individual's caloric needs include age, sex, weight, height, and physical activity level. These factors affect the body's basal metabolic rate (BMR), which represents the calories burned at rest. Age and sex significantly influence BMR, as metabolic rates tend to decrease with age and vary between genders. Physical activity level contributes to total energy expenditure, which includes daily activities and exercise. Understanding these factors allows individuals to tailor their dietary intake and fitness plans to meet their specific needs for weight management or performance.