"The principle behind weight loss is simple: you either have to burn more or eat fewer calories. To lose weight, you need to create an energy (or calorie) deficit by eating fewer calories, increasing the number of calories you burn through physical activity, or both. Typically, what is recommended as the safest method is a combination of eating fewer calories and burning calories through physical activity. While you do report that you are dieting and counting calories, you do not mention that you are doing physical activity and exercise, which, as mentioned above, is so important in the safe weight-loss equation.
Determining a safe daily calorie deficit can be difficult because every person is different when it comes to baseline metabolism, body size and composition, sex, age, and level of physical activity. What is easy to determine, however, is the fact that 3,500 calories equals about one pound of fat. Therefore, you have to burn 3,500 calories more than you take in to lose one pound. For example, if you cut 500 calories from your diet every day, you would lose about one pound a week. Or, if you are physically active, you can eat 250 calories less every day and burn 250 calories per day with your workout. Ideally, you do not want to lose more than one to two pounds per week, which means a safe calorie deficit would be to burn 500 to 1,000 calories per day through a reduced-calorie diet AND exercise.
Determining a safe minimum amount of daily calories can be difficult as well for the same reasons listed above. However, extreme restriction of consumed calories can significantly slow the metabolic rate, and hinder your weight-loss goals. The American College of Sports Medicine states that you shouldn't send signals to your body to conserve calories by detoxing or fasting. They recommend that women should eat at least 1,200 calories per day, and men should eat at least 1,800."
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