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Calorie tracking: How to track calories with a fitness tracker

Counting calories is easier than ever with devices and apps that do the work for you.
December 4, 2021

There are plenty of approaches to losing weight, including countless diets, exercise programs, and meal plans. For many people, calorie tracking is the most effective practice. This is where a fitness tracker becomes extremely useful: they allow you to monitor the number of calories you consume and burn to ensure you maintain a “deficit.”

If you haven’t ever tracked calories before, you may find the idea a little daunting. How do you keep track of everything you eat? How do you know how many calories you should be burning? What is a good deficit? Read on to find out everything you need to know about calorie tracking.

See also: The best fitness apps to get into shape and stay there

How to track calories burned in a day

In theory, losing weight is a simple equation. If you eat more calories than you burn, you will have a “surplus.” Those calories will then be stored as fat. If you burn more calories than you consume, your body will need to look for extra energy. That search leads to fat stores, which your body converts into energy.

Losing weight is a simple equation.

If you want to lose weight, all you need to (theoretically) do is calculate the number of calories you burn on a typical day and make sure to eat less than that number.

How many calories do I burn in a day?

how to track calories burned
Jimmy Westenberg / Android Authority

This is where things get a little complicated. Of course, there is no way to know with absolute certainty how many calories you burn on any given day. Instead, you will need to make do with a rough estimate. One way to calculate a reasonable number is by working out your Active Metabolic Rate (AMR). This is your Basal Metabolic Rate (BMR), or the calories you burn at rest, multiplied by a value representing your current activity level.

Even if you don’t move, you still burn calories by generally just being alive: breathing, maintaining tension in your muscles, digesting food, healing wounds, etc. This is your BMR. An individual’s BMR is calculated based on weight, height, age, and gender.

For women, the math looks like this:

BMR = 655.1 + (9.563 x weight in kg) + (1.850 x height in cm) – (4.676 x age in years)

For men, it’s as follows:

BMR = 66.47 + (13.75 x weight in kg) + (5.003 x height in cm) – (6.755 x age in years)

Once you know your BMR, determine which activity level below describes your lifestyle.

  • Sedentary: 1.2
  • Lightly active: 1.375
  • Moderately active: 1.55
  • Quite active: 1.725
  • Very active: 1.9

Multiply your BMR by the value best representing your current activity level to calculate your AMR. For example, for a moderately active lifestyle, multiply your BMR by 1.55. The is a rough estimate of how many calories you burn in a day.

An iPhone displaying a user's calorie tracking data in the MyFitnessPal app rests on a linen surface next to a Yoga Bar protein bar.

If you calculate an AMR of 2,500, you should aim to eat less than that amount to lose weight. The difference between your AMR and your target caloric intake is known as your deficit. A good deficit for most people is around 500 calories. If you aim too much higher than that, you are likely to feel tired and hungry and fall off the wagon. If you go too much lower, your progress will be slow and potentially frustrating.

Conversely, if you eat more calories than you burn, you will have what’s called a surplus. This will result in weight gain.

And to answer the question of “how many calories do I burn in a day?” the answer is roughly 1,600-2,400 for women and 2,000-3,000 for men.

Calorie tracking with fitness trackers

A man's wrist wears two fitness trackers with calorie tracking functionality, the Huawei Band 6 and the Xiaomi Mi Band 6.
Jimmy Westenberg / Android Authority
Left to right: Xiaomi Mi Band 6, Huawei Band 6

By now, you may have noticed that there are some issues here. What if, for example, you have a day where you are particularly active, and you burn a lot more calories? Or, what if you have a few sick days and you stay in bed all day? What if your activity is so varied that you can’t accurately make a prediction?

Note that a higher BMR will lead to a higher calorie burn during exercise — so making a flat multiplication like this is very simplistic.

See also: The best running watches you can buy

This is where your fitness tracker can come in handy. Devices from the likes of Fitbit, Garmin, and Samsung can actively track your activity using various sensors. This provides a much more accurate final estimate of your caloric burn.

Most devices will ask for your age, sex, weight, and height when you set them up for the first time (and you should be sure to update your weight as this changes). They will then monitor your activity levels throughout the day. They can determine the calories you burned walking, the calories you burned sitting, and the calories you burned during that impromptu play-time with the kids. Plus, your caloric burn during exercise. The result is a value that should be much more accurate than your static AMR calculated above.

Moreover, activity trackers can be a great form of encouragement because they show you how many calories you have left to burn, right on your wrist!

How to use calorie-tracking apps

Calories burned exercise
Adam Sinicki / Android Authority

Now you know how many calories you should be burning and how to track them. The next question is how to count calories coming in. The easiest method is to use a calorie tracking app such as MyFitnessPal or Lose It!. These apps help users log food and offer time-saving features so you can count calories with much less effort. Many also integrate with fitness trackers, allowing you to see your real-time deficit or surplus.

Don’t miss: Comparing the most popular calorie-tracking apps

MyFitnessPal allows you to scan food items and log them as meals or snacks. Scan the barcode and quickly get the total calories that food contains, along with other nutritional information. If you are cooking, you can scan the individual ingredients.

MyFitnessPal allows you to easily scan food items and log them.

Once an item is scanned, it will be saved for easy access. You can likewise store and retrieve common recipes. You can also look up countless items that the community has scanned. Type in “Heinz baked beans,” and you will quickly get those details; no scanning is even necessary.

Of course, you can manually enter calories if you want to guestimate, too.

All this makes the busy work of calorie tracking far less time-consuming, especially as many of us will repeatedly eat the same items. In fact, sticking to a fairly consistent meal plan for at least some meals of the day is a great way to easily reduce calories without putting too much thought into it.

The process of tracking food can also be eye-opening. You will quickly learn that you consume many “invisible” calories from sources such as cooking oil, butter, and beverages such as soda or specialty coffees. Cut these out of your diet, and you will immediately make progress.

Don’t forget to exercise

An Apple Watch SE displays a user's activity rings resting on wet rocks.
Eric Zeman / Android Authority

You can lose weight simply by cutting your calories, but adding exercise is highly advisable. Exercise allows you to eat more while staying in a deficit and accelerate your progress. More to the point, when you exercise, you increase your metabolic rate so that you burn more calories even at rest. In short, you increase your BMR because muscle is more metabolically active.

Again, the key is in the dosage: find a form of exercise that you enjoy and can stick with consistently. You don’t need to go to the gym or perform intense HIIT sessions: you can do something fun and simple, like going for runs or even playing a bit of Beat Saber.

And it’s not just about working out, either; it’s also about being more active throughout the day. That means walking more often (calories burned while walking account for a lot of energy expenditure during the day).

A physically fit man runs shirtless along a fence line.
Adam Sinicki / Android Authority

You may notice that your tracker provides two numbers after a walk: your total calorie burn and your active calorie burn. What does this mean? The active calories are what you burned by moving, whereas the total calorie count includes your BMR.

For example, your calories burned walking a mile might be somewhere in the region of 120. However, seeing as you would typically burn about 20 calories in the 15 minutes it took you, only 100 of those calories were active calories. This is useful to keep in mind if you want to know how to track calories accurately.

Why calorie tracking doesn’t work for everyone

Calorie tracking is a great way to lose weight, and it’s always the first place to start if you’re looking for predictable results. However, this method doesn’t work for everyone. A very passionate crowd of people will tell you that calorie tracking is simple math: the law of conservation. They say that if you aren’t losing weight with this method, you simply aren’t trying hard enough. I find this attitude to be unhelpful and unsympathetic.

Things that affect calories burned in a day

An Honor Band 6 tracks a users calories and displays the time.
Adam Sinicki / Android Authority

One open-ended variable is BMR. Your resting metabolic rate is dependent on countless factors that aren’t accounted for in this calculation, and that not even a fitness tracker can take them all into account. One of the most significant factors is hormone balance. If you have a slow metabolism due to hypothyroidism, low testosterone, or anything else, you won’t burn as many calories as other people. This won’t be reflected in your BMR or AMR.

Medication can also play a huge role. If you’re on testosterone replacement therapy (TRT), you’ll burn through calories in no time. Meanwhile, oral contraceptive pills can cause weight gain in some women. Antidepressants, anticonvulsants, and countless other medications have similar effects. Gut health also plays a role, as do nutrient deficiencies, genetics, and much more.

Remember, calorie tracking is never a precise art.

Cutting calories isn’t the problem, per se. The issue is that calorie tracking is never a precise art. If you can’t seem to lose weight, you can always try cutting back your caloric intake further, but there does come a point where this is untenable. Better would be to see your doctor, try a different diet (this is why things like intermittent fasting or keto can be effective for some people), or increase your exercise.

An Apple Watch Watch 5 rests on an iPhone, displaying a users activity and calorie tracking stats.

A final word of caution is not to consider calorie tracking as the be-all and end-all of health. Theoretically, you can lose weight by eating only donuts and never exercising, as long as you keep your deficit at a certain number.

Hopefully, you don’t need me to tell you that this is not a good idea. Food is not just fuel; it also provides the very building blocks that your body uses to build tissue, create enzymes, and fight infections. Therefore, a proper, balanced diet is vital. Likewise, the benefits of exercise go far beyond weight loss.

Learning how to track calories is one thing, but consider it just another tool in your arsenal. Although, with the right tracker and the right strategy, it can be an extremely effective one.