Heredity- May have a natural tendency towards a certain weight.
Activity Level- The more active you are, the more calories you burn. The less active you are, the less calories you burn. The number of calories you consume must be equal to the number of calories you burn. Maintaining a healthy weight requires an energy balance; tipping this balance can result in weight gain/loss.
Body Composition: The amount of fat, bone, and muscles are different for everyone. Depending on how big or small your bones are could affect your weight, how much muscle you don't have/have/How much fat one may have.
