In this low-calorie diet plan, dieters are allowed to take a total of 1000 calories of food per day to lose weight quickly in a short span of time. The rationale behind the 1000 calorie diet plan is that the drastic reduction of caloric intake results in weight loss, with little or no physical activity. The 1000 calorie plan generates energy shortage of 500 to 1000 calories and helps to burn approximately 8% of fat.