It’s easy to understand why The Biggest Loser was such a blockbuster show. After all, who doesn’t want to drop weight fast?

Unfortunately, that might not be the greatest idea. According to one 2016 study from the Obesity Society, the average The Biggest Loser contestant dropped a whopping 128 pounds. Impressive, right? But shockingly, six years later, the average contestant had actually regained 90 pounds.

In other words, the weight loss wasn’t sustainable, and most of the weight ended up coming back anyways.

If you’re trying to lose weight, there’s definitely a right way to do it. You can’t just wish your way to weight loss; it requires a plan. One of the first pieces of that plan is figuring out exactly how much you need to eat to lose weight.

We’ll walk you through how to calculate how many calories you should eat to lose weight in this article.

What’s a healthy amount of weight to lose?

Most experts, such as those from the CDC agree that losing one to two pounds of weight per week is a safe amount of weight to lose. That’s a far cry from The Biggest Loser contestants, who would drop as much as 34 pounds in a single week.

Why so little? It turns out that losing weight is more than just a once-and-done feat. Losing weight — and keeping it off for good, rather than for just today — requires you to completely change your lifestyle.

You need to get comfortable with eating less and exercising more — for the rest of your life.

That’s where The Biggest Loser contestants failed.The burn-and-starve tactics used to lose weight so quickly weren’t sustainable. By losing weight at a slower pace, you’ll be easing yourself into more sustainable lifestyle changes that you can manage well past when you’ve hit your target weight.

Another reason why you don’t want to lose weight too fast is because you could end up losing the wrong kind of weight. You want to burn fat. But when you lose a lot of weight in a short amount of time, you actually end up burning a lot of muscle and losing water along with that fat.

That’s also counterproductive to sustainable weight loss. No one wants to be dehydrated (headaches, anyone?), and with less muscle mass, you’ll be weaker and burn fewer calories throughout the day when you’re not working out.

How to Calculate Your Target Caloric Intake to Lose Weight

What we’ll be doing in this exercise is calculating how many calories you need to eat per day to lose weight. This involves a bit of math (nothing too difficult, don’t worry!), so you’ll need a few things:

  • A calculator
  • Pen or pencil, and paper (or your computer’s Notepad)

We’ll break down the calculations into a few steps.

First, we’ll calculate how many calories you need to eat per day to maintain your current weight. This maintenance caloric intake is important to calculate since it’ll establish a baseline for how many calories you burn each day. Then, we’ll calculate how big of a calorie deficit you’ll need to maintain each day to lose weight.

Finally, we’ll subtract your calorie deficit from your maintenance caloric intake to find out just how many total calories you need to eat per day to lose weight. This will be your target caloric intake. If you can eat around this many calories per day, you’ll be on track to meet your weight loss goals.

The equation looks like this: Maintenance Caloric Intake – Calorie Deficit = Target Caloric Intake

Step One: What’s your Resting Energy Expenditure?

Every person’s body burns a different amount of calories each day, based on a few different factors. If we cut out all the noise (like how different people exercise), we can focus just on how many calories it takes to run your body per day.

This is called your resting energy expenditure. It’s defined as the amount of calories that your body burns over a 24-hour period while at rest.

There are a lot of ways to calculate your resting energy expenditure using expensive lab equipment with trained professionals. But since we’re opting for the budget option, we can use a simpler approach and use an equation to estimate our resting energy expenditure.

The Mifflin-St.Jeor Equation

We’ll use the Mifflin-St. Jeor equation. You can find the entire equation here from Oxford Academic.

This equation was developed by a team of scientists and based off of a set of resting energy expenditure measurements from almost 500 different people. So far, this is the most accurate equation for estimating your resting energy expenditure without all the hoopla and expense of the fancy lab equipment.

Before we get started, though, we’ll need to convert a couple of your body measurements and write them down.

First, you’ll need to convert your body weight to kilograms. To do this, simply divide your body weight in pounds by 2.2 (there are 2.2 kilograms in one pound). For example, if you weigh 140 pounds, you’ll divide 140 by 2.2 to get 63.6 kilograms. Make sure to write this number down.

Second, you’ll need to convert your height from feet into centimeters. To do this, calculate your height in inches, and then multiply this number by 2.54 (there are 2.54 centimeters in one inch). For example, if you’re 5’4”, you are 64 inches tall (5 foot × 12 inches/foot + 4 inches = 64 inches). This means that you are 162.6 centimeters tall (64 inches × 2.54 cm/inch = 162.6 cm). Record this number as well.

Finally, we’ll plug these numbers into the Mifflin-St.Jeor equation. Use whichever one is applicable to you:

Women: 10 × weight(kg) + 6.25 × height(cm) – 5 × age(years) – 16 = Resting energy expenditure

Men: 10 × weight(kg) + 6.25 × height(cm) – 5 × age(years) + 5 = Resting energy expenditure

For a 63.6-kilogram woman who is 31 years old and 162.6 centimeters tall, the calculation looks like this:

10 × 63.6 kilograms + 6.25 × 162.6 centimeters – 5 × 31 years old – 16 = 1,481 calories per day

Step Two: What’s your maintenance caloric intake?

The above equation is helpful, but only if you don’t ever move during the day. Even the most sedentary of people expend some energy, even if it’s just to walk to the kitchen to get a snack.

So, to make this calculation more realistic, we need to factor in how much extra energy you spend per day.

To do this, we’ll need to multiply your resting energy expenditure by an activity factor:

  • Sedentary = 1.2
  • Lightly active = 1.375
  • Moderately active = 1.550
  • Very active = 1.725
  • Extra active = 1.9

Choose whichever factor applies to you while you’ll be working to lose weight. For example, if you’re normally pretty sedentary but will be starting to exercise for three days per week, choose “moderately active” instead of “sedentary.”

We’ll continue using the same example as above. Our 31-year-old female test subject expends 1,481 calories per day while resting. If she is “moderately active” each day, she’ll multiply her resting energy expenditure by 1.55:

1,481 calories per day (resting energy expenditure) × 1.55 = 2,295 calories per day (maintenance caloric intake)

This means that if our female test subject wants to stay at 140 pounds, she’ll need to eat around 2,295 calories per day.

Step Three: How fast do you want to lose weight?

So far we’ve calculated how many calories you need to eat to stay the same weight. But what we’re really interested in is losing weight, right? For that, we’ll need to calculate how many fewer calories you need to eat per day to reach your weight loss goals.

This is called a calorie deficit.

In other words, it’s the difference between how many calories you actually eat each day, and how many calories you need to maintain your current weight. If you have a calorie deficit, that means you’re eating less than you need to maintain your current weight, and so you’ll lose weight as a result.

According to the Mayo Clinic, you need to burn around 3,500 calories to lose one pound of fat. You can lose between one and two pounds per week sustainably.

If you want to lose….
1.0 pound per week, you’ll need a daily calorie deficit of: 1.25 pounds per week, you’ll need a daily calorie deficit of: 1.5 pounds per week, you’ll need a daily calorie deficit of: 1.75 pounds per week, you’ll need a daily calorie deficit of: 2.0 pounds per week, you’ll need a daily calorie deficit of:
500 calories 625 calories 750 calories 875 calories 1,000 calories

If you want to lose 15 pounds over the course of the next 15 weeks, for example, you’d need to lose one pound per week. In order to do this, you’ll need to maintain a daily calorie deficit of 500 calories per day.

Step Four: Calculate Your Daily Target Caloric Intake for Weight Loss

Let’s review what information we’ve calculated so far.

We’ve figured out how many calories you need per day to maintain your current weight (your maintenance caloric intake). We’ve also calculated the daily calorie deficit you’ll need to maintain to lose weight.  

Now, we’ll put those two things together to find out the number you’ve been waiting for: your daily target caloric intake in order to lose weight:

Maintenance caloric intake – daily calorie deficit = daily target caloric intake for weight loss

Let’s see how this works with our 31-year-old test subject. Remember, her maintenance caloric intake is 2,295 calories per day. She wants to drop 15 pounds in 15 weeks, so she needs to maintain a daily calorie deficit of 500 calories per day:

2,295 (maintenance caloric intake) – 500 (daily calorie deficit) = 1,795 calories

If our test subject can keep up her three-times-weekly exercise routine and eat 1,795 calories per day, she’ll stay right on track to meet her weight loss goal.

Step Five: Calculate Your New Maintenance Caloric Intake

Once you reach your new target weight, congratulations! You’ve worked long and hard for this, and you deserve your rewards.

Hopefully you’ve cemented in your new exercise and healthy eating habits. In order to stay at this weight however, you’ll need to calculate a new maintenance caloric intake. After all, your previous one was based off of your old, heavier weight.

If you plan on changing up your exercise habits at all — either exercising less, or more — you’ll need to factor that into your new maintenance caloric intake also.

To calculate your new maintenance caloric intake, all you’ll have to do in this case is repeat Steps 1-2 with your new numbers.

Let’s say our 31-year-old female test subject reaches her target weight of 125 pounds. If she decides to exercise less, say once per week instead of three times per week, she’ll need to use a new activity factor (say, 1.375 for “light activity”). In this case, the calculation would look like this:

10 × 56.8 kilograms + 6.25 × 162.6 centimeters – 5 × 31 years old – 16 = 1,413 calories per day (resting energy expenditure)

1,413 calories per day (resting energy expenditure) × 1.375 = 1,943 calories per day (maintenance caloric intake)

Our test subject started out needing to eat 1,795 calories per day while losing weight. Now, she’ll need to eat 1,943 calories to stay at her new target weight with her new exercise level.

What’s the best way to count my calories?

Most people underestimate the amount of calories they eat each day. That’s why a key step of this plan is to actually make sure you’re consuming the right amount of calories each day to meet your goal.

The only way to do this is by counting your calories each day, unfortunately. There are a few ways you can do this, though, and some are easier than others.

You can carry a small journal with you and record what you eat each day. Remember to include what the food is and how much of it you’re eating.

If you’re a smartphone user, however, an even easier way to do this is with an app. If you use popular fitness trackers like FitBit, you can record your food intake right in the app. MyFitnessPal is another great option that has tons of calorie and nutrition information for just about any food you’d ever eat.  

Bottom line

Calculating how many calories you need to eat to reach your weight loss goals — and counting them, day in and day out — isn’t the most fun thing in the world. But, it’s the best way to reach your goals if you’re serious about losing weight and keeping it off for good.

After all, exercising and cutting your calories is hard work. Why not take a moment each day to make sure that your hard efforts pay off in helping you reach your goals?

What other ways have you found to help cut calories to lose weight? Leave a comment below.