One question people often ask regarding weight loss is calories— how many calories should I be consuming each day? You need to determine what that number may be for yourself, for both weight maintenance and weight loss goals.
So, how many calories do you need in a day?
Tracking calories can be helpful to some, but to some people, it’s just anxiety-inducing and stressful. A healthy lifestyle and weight loss can be achieved without counting calories. But, if you choose to track or just want the
knowledge so you have it—because, after all, knowledge is power. Especially when it comes to your health there are some ways to calculate your calorie needs for yourself.
To start, everyone needs a certain amount of calories. That number will vary from person to person, based on a gazillion factors: age, size, genetics, lifestyle, activity level, health history, etcetera. Literally, every person will be different. Even if two people are the exact same height, weight, sex, age, they will each still need a different amount of calories.
So, how do you know what YOU need?
Your Basal Metabolic Rate, or BMR, is an estimate of the amount of energy, or calories, that your body expends at rest over the course of the day. You might also see it referred to as REE or Resting Energy Expenditure. So, if you did nothing at all for 24 hours—nothing, no eating, no walking, no moving, whatever—your BMR is the minimum
amount of calories that’s needed to keep your body’s organs and systems functioning.
There are a few different formulas to do the calculations.
It’s definitely not an exact science, but the Mifflin St Jeor Formula tends to be the most widely accepted for BMR.
So, let’s say Jill is 150 pounds, 5 foot 5 inches Her BMR is 1,401. That means she needs at least 1,401 calories per day just to function, without accounting for any movement, activity, etcetera, right? Well, hypothetically, yes, that is what it should mean.
But remember, we’re all different, and this calculator doesn’t take into account Jill’s health history, her diet history, her genetics, etcetera. So this number is really just a guesstimate, but we can use it as a starting point, because, when it comes to the wacky world of macros, you’re going to see that it’s a lot of trial & error.
After you have your BMR, the next step is to figure out how many total calories you need,
Next step is to find your Total Daily Energy Expenditure or TDEE. There are standard values of different activity levels that are used in the formula. and 1.9 is extremely active. Your TDEE, or total daily energy expenditure, is your BMR, multiplied by your activity level. So, that is meant to represent the energy or calories, that your body burns at rest and accounts for how active you are, in order to give you a guesstimate of the calories that you burn in an average day.
Now, there are a few problems with this:
Activity levels will vary based on where you look, and it’s very subjective
Most people won’t accurately guestimate their activity level. People tend to be overly generous with their choice. So, I recommend choosing the level that’s below what you think you are. And there are variables beyond that, too. So, remember, Jane might be the exact same stats as for June, but each of their bodies will burn calories differently with exercise and activity, so it’s not an exact science.
Unless you’re a training athlete, I’d say it probably wouldn’t be appropriate to mark “extremely active,” or even “very active.” I don’t say that to insult, anyone who works out a lot, you just have to recognize that this calculation is going to determine the number of calories you eat. So if you overestimate the activity level, your final number of daily calories will be higher than you actually need to achieve your goal—which probably means you won’t see much progress.
Counting calories for weight loss or weight gain
So, let’s say that Jill exercises about 4 times a week for 30 minutes and she has a desk job. So she doesn’t move
much other than that. She thinks her activity level is moderate but will mark light to be safe— better to underestimate than overestimate.
So the ultimate equation is Jill’s BMR, which is 1,401— let’s just say 1,400 for math’s sake— multiplied by 1.375,
meaning light activity level. We end up with: 1,925 calories. So, this is Jill’s Total Daily Energy Expenditure— the number of calories needed to maintain her current weight, accounting for her activity level.
If Jill’s goal were to lose weight, she would want to eat less than her maintenance level of calories. She wanted to gain weight, she would want to eat more than this. If she is happy with where she’s at, she can aim for that number. So keep this in mind: it’s not an exact science. This number may be way too high, or even too low for Jill. And the only way to know is trial and error.
Your calorie intake affects your metabolism
For instance, if Jill has been eating significantly less than around 1,900 calories for an extended period of time, her body may have adjusted to eating less, and that means that eating 1,900 calories may actually cause her to gain weight because she’s lowered her body’s baseline needs. Or, if she typically eats a lot more than 1,900 calories but hasn’t been continuing to gain weight, she may have trained her body to that higher number, and 1,900 may be enough for weight loss. It depends on each individual person.
Also, there are macro calculators online that will do this for you, too. But you’ll probably find that different one
is giving you different numbers for TDEE, and the reason for that is that they probably have slightly different numbers plugged in for activity level options. Just keep that in mind.
How much fewer calories you need to eat if your goal is weight loss?
Well, it depends how quickly she wants to lose weight. Most nutritionists suggest losing between 0.5 – 3 LBS/Week (0.2 – 1.3 Kg/Week). For a lot of people that feels too slow and discouraging, but any faster than that, and the weight probably just isn’t going to stay off once it’s lost. So if you can find the discipline to go a little bit slower, then that will help you maintain your weight loss in the long run.
If you want to lose 1 pound per week, you’ve got to consume 3,500 calories less per week, or about 500 calories less per day. So Jill’s maintenance calories would be calories so she has a calorie deficit. If she wanted to lose 2 pounds per week, she’d need to knock off 1,000 calories per day, bringing her to only 925 calories.
Now that is pretty low— I would guess that Jill is going to end up hungry, and then the plan won’t really be sustainable long-term. Plus, Jill risks damaging her metabolism by eating at such an extreme deficit for an extended period of time. So, that’s another reason we keep the weight loss slow.
Keep in mind I’m not saying that eating too little or too much for a day or two is going to hurt you but over a long term, bodies will adapt to what we do regularly. But, now you at least know the science behind calculating out the caloric needs.
So is it an exact science?
Are those numbers written in stone? definitely not.
But it’s a starting point, so if that number helps you on your journey, great! If it doesn’t help, then don’t worry about it. I don’t think it’s necessary to track everything we eat to be healthy or even to lose weight. Focus on whole foods, and eliminate processed foods as much as possible, rather than focusing on calories. The quality of food matters far more than the quantity.
And, there are other factors at play when it comes to weight loss, like hormones. But, knowledge is power and learning how calories and macros works are only going to help you make some more informed decisions, whether you count calories or not.