Calories in, calories out: It’s the golden rule of body weight. If you want to make any changes to your body weight, you first and foremost need to pay attention to your energy balance.
But what exactly does that mean? There’s so much information out there about calorie requirements that it can be confusing to decipher your calorie requirements for weight loss, calorie intake to gain muscle, and everything in between. The good news is that all it takes is a bit of tracking and some math to determine your calorie needs, no matter what your fitness goals are.
Here’s your ultimate guide on how to figure out your daily caloric requirements, plus how to figure out calorie intake to lose weight, gain muscle, and everything in between.
First: what is a calorie, anyway?
A calorie is simply a unit of measurement used to determine how much energy is in a given food. (Just a note: the term “calorie" is often used interchangeably with the term “kilocalorie,” which is why you sometimes may see calories referred to as a “kcal,” which is short for kilocalorie.)
Like any well-oiled machine, your body needs energy in order to carry out all the many tasks that it does on a daily basis, from exercising to using your brain, which is why you need a certain amount of energy from your food on a daily basis.
Now let’s talk about “maintenance calories.”
Your “maintenance calories” are your calorie requirements per day to maintain your weight – in other words, staying exactly where you are, no gaining, no losing. Keep in mind though, that even if you eat at maintenance, your body weight can still fluctuate from day to day due to a number of variables that influence your hydration status. This doesn’t mean you’ve gained or lost weight.
Maintenance calorie intake needs are determined by a couple of different factors, including:
- Basal Metabolic Rate (BMR), which is the minimum number of calories your body needs to survive and carry out its regular functions while you’re at rest (aka not doing much of anything at all).
- Activity thermogenesis, aka the calories that you burn from exercising
- Non-exercise adaptive thermogenesis (NEAT), or the energy that you use for everything that’s not physical exercise
- Thermic Effect of Food (TEF), or the amount of energy that is required to digest and absorb foods.
Put together, these four variables add up to your total daily energy expenditure (TDEE), which is essentially your specific calorie requirements to maintain weight.
- If you eat more calories than this, your body holds on to that extra energy and stores it, leading to weight gain.
- If you eat fewer calories than this, your body uses that stored energy for energy instead, which will lead to weight loss.
Important: your calorie requirements to maintain weight can change!
Because your maintenance calories are dependent on so many different factors, your caloric requirements to maintain weight is not a set number.
We see this often when it comes to people who are trying to lose weight. After a long diet, they might try to take their calorie intake back up to what they determined was their maintenance calorie level but actually end up gaining weight as they increase their calories. Why is this?
When you diet and lose weight, you undergo various changes, such as decrements in your metabolic rate, that result in lower TDEE. This means that your metabolism can actually slow down as you lose weight, and that the number of calories you need to maintain your body mass is likely to be much lower after a diet versus the middle of a bulk when you have more mass that needs to be maintained.
This point has been illustrated by several studies, including the MATADOR study published in the International Journal of Obesity in 2017. Researchers randomly placed 51 obese men in either an intermittent fasting or a continuous calorie-restricted diet for sixteen weeks to evaluate the effects of calorie restriction on metabolism. At the end of the dieting phase, they found that there were significant reductions in their resting energy expenditure than at the beginning of the study.
The ultimate cheat sheet: How to calculate calorie needs for every kind of weight goal
Now that we’ve covered the basics of how your calorie intake can affect your weight, let’s put it all together! Here’s how to calculate calorie intake to maintain, lose, or gain weight.
How do you figure out your maintenance calories? The Calorie Calculator
Whether you’re trying to calculate your calorie intake for weight loss or weight gain, you’ll first need to identify your maintenance calories. You have 2 basic options to figure out your maintenance calories.
OPTION 1: The Muller Equation
Use an equation to estimate your BMR (Basal Metabolic Rate). We like the Muller equation, since it takes your body composition into consideration, rather than just your weight, age, and height.
Once you finish this BMR calculation, which shows approximately how many calories your body systems need to function at a minimum, you would then multiply this number based on your activity level:
- SEDENTARY: little to no exercise; multiply BMR*1.2
- LIGHT ACTIVE: light exercise 1-3x per week; multiply BMR*1.375
- MODERATE ACTIVE: moderate exercise 3-5x per week; multiply BMR*1.55
- VERY ACTIVE: hard exercises 5-7x per week; multiply BMR*1.725
The resulting number will be an approximation of how many calories your body currently needs to maintain weight. But while these equations are a great place to start figuring out your calorie requirements, they may not be completely accurate.
OPTION 2: Real World Testing
For a much more accurate way to figure out your calorie requirements to maintain weight: simply track your calorie intake over time and compare it to your daily weight changes!
How to do this:
- For approximately 1-2 weeks, keep a food diary or track your calorie intake on a mobile app.
- Meanwhile, check in on a scale every day to track whether or not you’re seeing body weight changes.
At the end of this period, compare averages of your calorie intake to your body weight to see what they are doing relative to each other!
- If your weight is staying approximately the same, you’re likely eating at your maintenance calorie level
- If you’re gaining weight, you’re likely eating more than your calorie intake to maintain weight
- If you’re losing weight, you’re likely eating fewer calories than your necessary calorie intake to maintain weight
This method might take a little longer than simply plugging some numbers into a calculation, but it’s a great and practical way to figure out your specific calorie intake needs.
How to figure out calorie deficit (aka how to calculate my calorie intake to lose weight)
Once you figure out your calorie intake to maintain weight using either of these two methods, you can now figure out your calorie intake for weight loss!
First, you’ll need to set a goal for the rate at which you want to lose weight. It’s a commonly cited “rule” that one pound of body fat is equivalent to approximately 3,500 calories, but many scientists now believe that this statement is outdated and not completely accurate. However, what we do know is that we should be aiming for a moderate calorie deficit for weight loss, so it’s a decent place to start if you’re looking to set a timely goal (just take that exact number with a grain of salt). Then, once you’ve determined how many calories you’ll need to eliminate to align with your weight loss rate goals, you can subtract that number from your maintenance calorie requirements to approximate the number of calories you’ll need to eat per day.
So here’s how to use this information to calculate your calorie deficit for your expected rate of weight loss:
- If you wanted to lose 1 lb per week, you would want to subtract about 3,500 total calories through the week. If you divide 3,500 calories by seven days, you would be looking at a daily deficit of 500 calories per day, meaning you would need to subtract 500 calories from your maintenance calorie requirements.
- If your goal is to lose 2 lbs per week, you would aim to eliminate roughly 7,000 total calories from your diet. Dividing that 7,000 calories over the course of seven days equals a 1,000-calorie deficit below your maintenance calorie requirements.
Now, when it comes to weight loss, it’s a good idea to decrease your calories gradually enough that it’s more sustainable for you in the long run. So as a general guide, we recommend decreasing your calories by about 15-20% below maintenance to begin with.
How to calculate calorie intake for muscle gain
On the other side of the coin, you might be looking to bulk, or determine your calorie intake to gain muscle. In this case, you’ll need to figure out calorie intake to gain weight, which means that you’ll be adding calories to your daily intake.
Similarly to figuring out your calorie intake to lose weight, you’ll need to set a goal for yourself based on your targeted rate of weight gain. Our recommendation for this: try adding about 200-300 calories per day. Again, you’ll want to make sure that you’re increasing your caloric intake for slow and sustainable weight gain, rather than adding on a ton at once.
A quick note on quality vs. quantity in your diet for weight loss
Just to dispel a common myth: when it comes to losing, gaining, or maintaining weight, the number of calories you eat is still a more important factor than the portion of macronutrients you’re eating (although, of course, this definitely still matters for your health and body composition in the grand scheme of things).
Yes, your body processes macronutrients differently. For example, there’s evidence that high-protein diets can lead to more weight loss versus diets that are higher in carbohydrates but are equal in calories. Similarly, diets that are higher in fiber are also helpful for weight loss since your body does not digest fiber in the same way as it does simpler carbohydrates.
But ultimately, portion control and calorie counting is going to be the deciding factor in your calories-in-calories-out equation (more on that in a moment). Even if you’re following a high-protein, high-fiber diet, it’s definitely possible to consume more calories than your body needs, which can then lead to weight gain.
The bottom line
Whether you’re looking to gain muscle, lose fat, or stay exactly where you are, your first step is to figure out exactly how many calories you need to take in every day in order to make it happen. Figuring out this “magic number,” which is never fixed and can vary hugely based on your current physical fitness and activity level, can help guide the entirety of your meal planning and supplement regimen for peak goal progression.
