How Many calories Did You REALLY Burn?

woman sprinting over ground
Sprinting is a great way to burn a lot of calories in a short amount of time.

To lose weight, you must burn more calories than you consume. The problem is, people often overestimate how many calories they burn with exercise and underestimate the amount of calories they take in per day. I am myself guilty of this. It’s so easy to forget to count the milk you put in the three coffees you drank, or miscalculate how big that piece of grilled salmon really was. Just because you spent 30 minutes on an elliptical and the monitor screen says you burned 400 calories doesn’t necessarily make it so.  According to study done in 2018, the calorie calculator on an elliptical can be off by as much as 130 calories each thirty minutes! That’s 260 calories in an hour. The good news is, that although men tend to burn more calories than women in the same amount of time, the study didn’t find the difference to be significant. Don’t trust your fitness tracker either. A recent study by Stanford Medicine found that they are only reliable when it comes to measuring your heart rate. Out of the seven wristband activity monitors, the most accurate one was still 27% off. The least accurate was a shocking 93% off.

Things to keep in mind when measuring calories burned.

  • Your sex. Are you a man or a woman? Men generally have more muscle and less body fat, which means they’ll burn more calories. But a woman with the same amount of body fat and muscle mass will burn the same amount of calories.
  • Your age. The younger you are, the more calories you’ll expend. The main reason you burn fewer calories as you age is because you lose muscle mass. You can easily combat this by strength-training at least twice a week to rebuild/maintain your muscle mass. Check out my Body Type article to determine how much weight-training you need.
  • Your size. A 250- person will burn more calories swimming 30 minutes than someone who weighs 125 pounds, their body composition notwithstanding. This is why you’ll need fewer calories/day after losing, say, 15 pounds.
  • The weather. It might feel like you burn more calories running when it’s cold outside, but that’s not true. You’ll burn more calories running those six miles in the heat because the body has to work harder to keep its body temperature down. It achieves this by making you sweat profusely.
  • Your body composition. People with lots of muscle mass on their bodies will burn more calories than people with less. A pound of muscle needs 6-7 calories/day to sustain itself, while a pound of fat only needs about 2. That means someone with 20 pounds more muscle than another person will burn about 100 calories more per day while at rest. It may not sound like much, but, trust me, it adds up.
  • Your workout intensity. This is the most obvious for people who lift weights. The amount of calories burned during an hour of weigh training can vary by several hundred calories. If you do compound exercises vs bicep curls, you’ll burn more calories. If you take shorter rests between sets, you’ll burn more calories. If you slept well and have more energy, you may lift heavier and faster. This will result in more calories burned in the same amount of time. Check out my article Best Workout to Shed Weight for more information about this.
a very lean, muscular woman's abs
A woman this muscular is going to burn more calories than many men!

There are plenty of activity calorie counters available on the internet. The accuracy of these counters will depend on the how much data about yourself you can enter into it. For example, if the counter only requires you to enter your age, sex, and weight, it won’t take into account how much muscle you have (or if it’s hot outside). If you’re 60 years old, but with the muscle mass of a 30-year-old, the counter will be way off.

Also, there are many activity calorie charts to tell you how much calories a certain activity used in a certain amount of time. They can be very inaccurate. For example, one such chart might tell you that a 154-lb. individual burns 279 calories per hour of water aerobics and 440 playing basketball an hour. However, if this individual plays basketball at a leisurely pace but pushes himself hard during the water aerobics, the 279 calories could instead apply to the basketball and 440 to the aerobics. Monitor your exertion levels by asking yourself how hard your workout feels. Your exertion should stay at “somewhat hard” level for these numbers to be the most accurate. On a scale from 1-10, that would be about a six.

My favorite calorie counter is one by Precision Nutrition. (I am a twice-certified PN coach.) It might not be a an activity calorie counter, but I think you’ll find it extremely helpful if you’re trying to lose/maintain/add weight. It’s the most precise counter out on the market, far more detailed than any other calculator you can find at the moment. Try it out and let me know what you think of it in the comments!

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