Calories are everything when it comes to how much weight you lose. Losing weight is a simple math problem, and calories are the units we use to solve it. Calories are a way for us to measure energy. With that said anything that we do – from the normal physiological processes that keep us alive, to physical activity – requires energy and thus, calories to do it. Foods also have a caloric value to them that’s based on the amount of energy-yielding nutrients (proteins, carbohydrates, fats, and fiber) that they contain.
To maintain your weight, the amount of calories you consume from food would have to equal the amount of calories your body burns on a daily basis – essentially canceling each other out. In order to lose weight you must consume less calories from food than the amount of calories you burn though activity and your body’s metabolism. When you create a deficit between how many calories you consume and how many calories you burn it requires your body to use stored fat for energy. We know that 1 pound of fat equals 3500 calories, so in order to reduce your weight by 1 pound a week, that would require you to create a deficit of 3500 calories (500 calorie daily deficit x 7 days); to lose more weight, simply create a bigger deficit. For example, reducing your food intake by 500 calories a day and increasing your physical activity to burn an extra 500 calories a day will create a 1000 calorie daily deficit, which will lead to 2 pounds of weight loss a week.