How Many Calories Should You Eat to Lose Weight?

Do you fear that you are eating too much for your body size or fitness level? Have you found yourself wondering how many calories you should be eating to lose weight?

While determining how many calories each individual should eat for successful and healthy weight loss isn't exactly rocket science, it can be confusing. SparkPeople's free program makes it simple by creating a personalized calorie range based on you as an individual; for for those who want a deeper understanding of how we come up with these recommendations, this article wiill explain the formulas, mathematics, and general nuts and bolts, in nine easy steps. Whether you are a SparkPeople member or not, you can use the formulas here to calculate your personal calorie range.
A note for SparkPeople members: There are two different methods SparkPeople uses to determine your calorie range. This article assumes that communication between your Fitness Tracker and your Nutrition Tracker is turned OFF. This is the default option for all members who joined the site before July 10, 2013. If you are not sure which method you are using, click here. If you know you are using the other option (where communication between your trackers is turned ON) the article below will not apply to you. Click here instead.

How to Calculate Your Weight-Loss Calorie Range

Case Study
To show how these calculations work, we will use Jane as an example. Here are Jane's important stats that will affect her weight loss and calorie needs:
  • Age: 35
  • Gender: Female
  • Height: 5 feet, 7 inches (67 inches)
  • Current weight: 180 pounds
  • Goal weight: 160 pounds
  • Fitness plan: Three 30-minute cardio sessions per week
  •  Activity level:  Sedentary (has a desk job) 

Step #1: Determine Your Body Mass Index
Body Mass Index (BMI) is a quick and easy formula for determining if your weight is appropriate for your height. It has recently been used to quantify an individual's obesity level. You can use this tool to determine if you need to lose weight in the first place. To the right is the general formula, using Jane as an example.

According to the USDA guidelines, a BMI less than 25 is healthy, from 25 to 29.9 is classified as overweight and anything higher than 30 is considered obese.

Keep in mind that BMI is just one part of your health profile. It measures a general relationship between weight and height but does not distinguish between fat (which doesn't weigh much) and muscle (which weighs a lot). A thin but sedentary person could have a healthy BMI but be flabby and out of shape, for example. Finally, BMI is not considered reliable for everyone, including children, pregnant women, body builders, and the frail elderly. Read SparkPeople's Fitness Reference Guide: Body Composition for more information about BMI.
Step #2: Set Your Weight-Loss Goal
Research shows that slow, gradual weight loss is not only healthier, but that individuals who lose weight slowly tend to keep the weight off. Many fad diets promise excessive amounts of weight loss in a short amount of time, which can be dangerous and impermanent. Therefore, SparkPeople will NOT let people set a weight-loss goal that is too aggressive. While the weight may come off slowly, you will have a better chance of maintaining your weight loss over time.

If you set an aggressive weight-loss goal (2 pounds per week or more), your calorie range will be lower. If you set a gradual weight loss goal (1 pound per week or less), your calorie range will be higher.

Step #3: Plan for Fitness

SparkPeople encourages its members to exercise at least 3 days per week, and our program assumes you're doing 30 minutes of walking, 3 times per week unless you edit your settings to tell it otherwise. You can edit your fitness program settings to indicate how much you exercise on a weekly basis so your daily calorie goals are as accurate as possible.

Being honest and accurate here is important. An individual who exercises a lot needs more calories than a person who doesn’t exercise at all. If you do exercise but did not account for it during set-up, your calorie recommendation could be too low; this could slow down or completely prevent weight loss. Similarly, if you do not exercise but said that you do, your calorie recommendations will be too high, also making it harder for you to lose weight.

Step #4: Meeting Your Basal Metabolic Needs
Your Basal Metabolic Rate (BMR) is the number of calories your body needs to perform basic, everyday functions like circulating blood, digesting food, and breathing. SparkPeople uses the Harris Benedict Formula to calculate your BMR, which differs between men and women.

This number reflects how much Jane would need to consume, just to live—even if she did nothing but lie in bed all day. It will come into play in the next equation.

Step #5: Sedentary Lifestyle Assumption
SparkPeople makes the assumption that everyone is fairly sedentary throughout most of the day, except for the planned fitness activities they do. This sedentary lifestyle includes light walking on the job, light housekeeping, deskwork, running errands, etc. To determine the additional calorie needs of a relatively sedentary lifestyle, multiple your BMR by 1.2 to get the number of calories you need for both basal metabolic functions and light activity. 

Step #6: Total Your Daily Calorie Needs
However, if you are exercising (Step #3), your body needs even more calories. To account for these calories, first divide your weekly calories burned goal (Janes’s is 670, listed in Step #3) by 7, which gives you the average number of calories you burn through exercise each day. 

These fitness calories must be added to get your total daily calorie needs. So, add Sedentary Lifestyle Calories (from Step #5) + Fitness Calories. 

Jane can eat this much daily and maintain her weight, but in order to lose weight, she needs to eat less than this. That’s where Step #7 comes in. 

Step #7: Account for Rate of Weight Loss
One pound of body fat equals 3,500 calories. Therefore, to drop 1 pound per week, you must create a deficit of 3,500 calories over the course of seven days, which equals 500 calories per day. To lose 2 pounds per week (3,500 calories x 2 pounds = 7,000 calories), you must cut 1,000 calories daily. 

So by subtracting your weight loss rate (for example, 1 pound or 2 pounds weekly) from your Total Daily Calories (Step #6), you will create an appropriate caloric deficit in your body, and achieving your desired weight loss. There is no reason to cut additional calories, since this has already been included in the formula. 

Step #8: The SparkPeople Calorie Range
SparkPeople comes up with your individual calorie range by subtracting 250 calories from your weight loss calorie goal (Step #7) for the low end of the range, and adding an additional 100 calories to your weight loss calorie goal for the upper end of the range. 

Once again, there is no reason to eat fewer calories than SparkPeople recommends, since this has already been done by the SparkPeople formula. 

Step #9: Rounding the NumbersTo make life easier, SparkPeople then rounds these numbers up or down to the nearest 10.

Step #10: For Your Health and Safety
The SparkPeople program will NOT allow any female to eat less than 1,200 calories daily or any male to eat less than 1,500 calories daily.

When calories drop too low (usually below 1,200 calories for women and 1,500 calories for men), your body's protection mechanism switches on. In order to conserve energy, the body lowers your metabolism and you will not burn calories as quickly. This results in a slower weight loss rate, or sometimes prohibits any weight loss from occurring.

When your caloric intake falls below these levels, it is also extremely difficult to obtain all the nutrients that your body needs for health and survival. These very low calorie intakes can also lead to other health problems such as eating disorders, gout, gallstones, and heart complications.