If I Want to Lose 2 Pounds Each Week, How Many Calories Should I Have Every Day?

You have four weeks to drop eights pounds and you've decide to go on a diet that will help you shed two pounds a week. To do this, you'll need to run a daily energy deficit of 1,000 calories in order to start and maintain this level of weight loss. Exactly how many calories you eat daily requires a little more work and depends on a number of factors that include your sex, age, height and activity level.

Counting calories isn't always fun. However, it's often necessary when you're trying to lose weight. The laws of thermodynamics dictate that you must burn more energy than you consume for you to lose weight. This energy is measured in calories.

There are 3,500 calories in one pound of fat. Thus, it follows that, if you want to lose two pounds a week, you'll need to run a caloric deficit of 7,000 calories each week, which equals 1,000 calories a day.

If you plan on losing weight even faster, it's important to note that the Centers for Disease Control and Prevention recommends more gradual weight loss, running between one to two pounds per week, in order to promote long-term success. Therefore, you'll need to limit your caloric deficit to 500 to 1,000 calories per day. MedlinePlus classifies a diet that aims to lose more than two pounds a week as a "rapid weight loss diet" that is rarely recommended by healthcare providers and indicates that such diets should only be used for short periods.

If you plan to lose two pounds a week, you'll need to consume 1,000 less calories than your Total Daily Energy Expenditure (TDEE). Your TDEE, measured in calories, is the total number of calories you burn in a day. Authors of a February 2014 review study published in the Journal of the International Society of Sports Nutrition (JISSN) explain that TDEE is the sum of the following four factors:

• Basal Metabolic Rate (BMR)
• Non-Exercise Activity Thermogenesis (NEAT)
• Thermic Effect of Food (TEF)
• Exercise Activity Thermogenesis (EAT)

BMR is the total calories burned during normal bodily functions when you are at rest, including breathing, sitting and thinking. NEAT represents that total amount of energy you burn during "non-exercise" movements like fidgeting and changing your body's positon. TEF is the total energy you burn when digesting, absorbing and assimilating food. EAT represents the calories burned via physical activity and exercise. These four factors are added together to give your TDEE, which is represented in the following equation:

TDEE = BMR + NEAT + TEF + EAT

It's important to note that TDEE is only an estimate of your energy expenditures. The best you can do today is to perform fairly sophisticated lab testing. The more common yet less accurate way to measure TDEE requires you to plug variables like your age, sex, height and activity level into an additional set of equations (Mifflin-St Jeor and Harris-Benedict equations). These equations are the source of many popular TDEE calculators found online.

To quickly and conveniently determine your TDEE, use the Body Weight Planner provided by the National Institute of Diabetes and Digestive and Kidney Diseases. Set the number of days to reach your goal to "1" and set your Physical Activity Change level to "0%". The first number given at the end (to "maintain your current weight") is your TDEE. Subtract 1,000 calories from your TDEE value to determine your ​​daily caloric goal​​, the number of calories you should eat daily to lose two pounds a week.

​Read More​: Calories, Weight and Height According to Age

Once you have calculated your daily caloric goal, you can start cutting calories to put your estimated number to the test. In order to do this, you need to start cutting calories in accordance with a diet plan. There are two primary ways to cut calories in a diet: portion control and/or eating lower calories foods.

Begin tracking your calories, and follow a meal plan. Use a calorie tracking tool like the Meal Plan Calculator provided by MyFoodData.com to track your calories, design meal plans and track meals. The nutritional data found on MyFoodData.com is sourced from United States Department of Agriculture and is a reliable tool for weight-loss diet planning.

For many people, measuring foods with a food scale may be necessary to better ensure that they're on track with meeting their daily caloric and nutritional targets. Given that cheating on diets is common, it is a good idea to have measured, preset portion sizes to limit this problem. This practice is called "meal prepping" and you can use the meal prep strategies outlined by the Harvard T.H. Chan School of Public Health to take meal planning to higher degree. A good meal prep strategy can help you save money and better ensure you meet daily caloric goals.

Now that you know your daily caloric intake you'll need to choose a diet, which will ultimately dictate your balance of macronutrients. Sometimes it seems as though there are an infinite number of popular weight loss diets to choose from. Among the more popular and well-studied diets are low-fat and low-carb diets. Although the long-term effects of these diets are still under investigation, current data suggests that the two approaches are similar in their efficacies towards weight loss.

Authors of a large-scale meta-analysis study published in the Journal of the American Medical Association in September 2014 found that commercial low-carb and low-fat diets showed significant weight loss in subjects but that the differences between those named diets were minor. The meta-analysis included the Atkins, Zone, South Beach, Jenny Craig, Rosemary Conley, Volumetrics, Slimming World, Biggest Loser, Weight Watchers, Ornish and Nutrisystem diets. The investigators concluded that patients, when deciding between any of the commercial low-carb and low-fat diets, should adopt the diet that they are most capable of adhering to.

Consider trying a commercial diet since these often come with useful resources, guidance materials and a community of dieters that can help you get started and adhere to a long-term diet strategy. These programs may include their own meal plans, meal prep systems, training videos and other useful resources.

Keep in mind that some of these commercial diets may ask you to lose more or less than your goal of two pounds per week. Also consider consulting a qualified healthcare provider and informing them of your plans to adopt a new weight loss diet.

​Read More​: Can You Lose Weight Just by Eating Healthier?

According to Mayo Clinic, diets often require an "initiation" phase. During this period, which takes place in the first two weeks of dieting, weight loss can range from six to 10 pounds. Much of this weight loss is loss of water weight rather than fat loss.

When restricting calories, especially those coming from carbohydrates, the liver begins to breakdown glycogen. Glycogen is a reserve supply of glucose, which is stored mostly in the liver and muscle, that is broken down into glucose molecules to supply the brain and body with energy when it is limited or unavailable (i.e., while dieting). According to a September 2015 study in the European Journal of Applied Physiology, glycogen is bound to roughly three grams of water for every gram of glycogen. Therefore, expect to lose a significant amount of water weight during the first two weeks of dieting.

After completing the initiation phase, you can start measuring your progress on your diet. Weigh yourself at the end of each week. You should, in theory, lose two pounds a week. If not, adjust your caloric intake slowly so that it better reflects your real-life, empirical findings.

In addition to caloric intake, muscle mass and metabolism play roles in determining your rate of weight loss. According to Mayo Clinic, your metabolism is determined by the following:

• ​Body size and composition​. Larger or more muscular people burn more calories at rest.
• ​Sex​. Men burn more calories than women because they tend to have more muscle and lower body fat.
• ​Age​. Older people burn less calories, since they progressively lose muscle mass with age.

The story on metabolism is much more complicated, however. Your metabolic rate is also partly determined by genetic makeup, diet composition, hormonal controls and environmental factors impacting sleep, lifestyle, physical activity and stress. According to the aforementioned JISSN review study, the metabolic rate adaptively slows in response to weight loss. This adaptation makes long term weight loss hard, requiring that you lose weight in a stepwise, incremental fashion and avoid extreme energy deficits—greater than 1,000 calories per day—to ensure a steady, slow rate of weight loss.

One hour of exercise may burn 500 calories, but a single donut can wipe out that entire effort in a matter of minutes. Therefore, a plan that seeks to limit calories through exercise cannot ignore diet. Exercise is much more meaningful and useful in the context of a sound and well-regulated dietary regimen.

Aerobic exercise is the most efficient way to burn calories. This includes activities like bicycling, running and swimming. According to Mayo Clinic, you should include at least 30 minutes of exercise in your daily routine. However, you may have to dedicate more time towards aerobic exercise in order to meet your daily caloric goal. If you're unable to get the full 30 minutes at once, split up your workout into 10-minute blocks spread throughout the day.

Strength training should be included at least two times a week, according to Mayo Clinic, since muscle mass is critical in increasing metabolic rate. Since running a calorie deficit for weight loss not only leads to loss of fat but can also result in loss of muscle, moderate strength training exercises during weight loss regimens can help maintain muscle mass and prevent deceleration of the body's metabolic rate.

​Read More​: Calories Burned From High-Intensity Interval Training