Losing weight, gaining weight or maintaining your weight depends on the amount of calories you take in and use up during the day, otherwise referred to as energy balance. Learning how to balance energy intake (calories in food) with energy output (calories expended through physical activity) will help you achieve your desired weight.
Although the underlying causes and the treatments of obesity are complex, the concept of energy balance is relatively simple. If you eat more calories than your body needs to perform your day’s activities, the extra calories are stored as fat. If you do not take in enough calories to meet your body’s energy needs, your body will go to the stored fat to make up the difference (Exercise helps ensure that stored fat, rather than muscle tissue, is used to meet your energy needs.) If you eat just about the same amount of calories to meet your body’s energy needs, your weight will stay the same.
On the average, a person consumes between 800,000 and 900,000 calories each year! An active person needs more calories than a sedentary person, as physically active people require energy above and beyond the day’s basic needs. All too often, people who want to lose weight concentrate on counting calorie intake while neglecting calorie output. The most powerful formula is the combination of dietary modification with exercise. By increasing your daily physical activity and decreasing your caloric input you can lose excess weight in the most efficient and healthful way.
Each pound of fat your body stores represents 3,500 calories of unused energy. In order to lose one pound, you would have to create a calorie deficit of 3,500 calories by either taking in 3,500 less calories over a period of time than you need or doing 3,500 calories worth of exercise. It is recommended that no more than two pounds (7,000 calories) be lost per week for lasting weight loss.
Adding 15 minutes of moderate exercise, say walking one mile, to your daily schedule will use up 100 extra calories per day. (Your body uses approximately 100 calories of energy to walk one mile, depending on your body weight.) Maintaining this schedule would result in an extra 700 calories per week used up, or a loss of about 10 pounds in one year, assuming your food intake stays the same. To look at energy balance another way, just one extra slice of bread or one extra soft drink a day – or any other food that contains approximately 100 calories – can add up to ten extra pounds in a year if the amount of physical activity you do does not increase. If you already have a lean figure and want to keep it you should exercise regularly and eat a balanced diet that provides enough calories to make up for the energy you expend. If you wish to gain weight you should exercise regularly and increase the number of calories you consume until you reach your desired weight. Exercise will help ensure that the weight you gain will be lean muscle mass, not extra fat.