Which of the following factors is known to influence body weight?

The factor that significantly influences body weight is the combination of eating and physical activity habits. This encompasses the types of foods consumed, portion sizes, and frequency of meals, as well as the level of physical activity an individual engages in. Caloric intake and expenditure are critical components of weight management; therefore, understanding the balance between what is eaten and how much one exercises is vital for maintaining a healthy body weight.

Lifestyle choices in eating and physical activity have direct effects on metabolic rates, body composition, and overall energy balance. For instance, a diet high in processed foods and sugars, coupled with a sedentary lifestyle, may lead to weight gain, while a balanced diet rich in nutrients combined with regular physical activity supports weight maintenance or loss.

The other factors mentioned—such as allergies, hair color, and favorite food preferences—do not have a direct or significant impact on body weight regulation. While allergies and intolerances affect what some individuals can eat, they are more about health conditions than about influencing weight under normal circumstances. Hair color is unrelated to body weight, as it does not affect metabolism or energy expenditure. Favorite food preferences can influence dietary choices, but they are not as impactful as the holistic combination of eating and activity habits in managing body weight.