All diets boil down to one simple formula- calories in versus calories out. Any food or beverage that is consumed gives the body calories.
Calories add up over time, and it takes 3,500 calories to make a one pound change. To gain a pound, a person has to consume 3,500 more calories than they burn. To lose a pound, a person must burn 3,500 more calories than they consume.
Nutrition experts agree that a safe weight-loss is approximately one to two pounds per week. Quick weight loss of more than two pounds per week is almost always regained—often with extra bonus weight.
To lose one pound per week, reduce calorie intake by 3,500 calories per week. This number can seem overwhelming, but by dividing 3,500 by the number of days in the week, the result is 500 calories.
To lose one pound a week, just create a deficit of 500 calories every day. The good news is that a 500 calorie deficit can be created more easily by breaking it down into 250 fewer calories that go into the body and 250 more calories that go out of the body.
So by cutting 250 calories from food and by increasing the amount of physical activity by 250 calories, a 500 calorie deficit can be created quite easily, which over a period of one week should translate into a one pound weight loss.