- Fitness trackers overestimate calorie burn by as much as 93%, studies suggest.
- It’s better to create a calorie deficit through nutrition than through exercise, experts say.
- Workout in ways you enjoy to make fitness a sustainable part of your life, not a way to burn calories.
- Read more Working It Out here.
- Visit Insider’s homepage for more stories.
I’m trying to lose weight so have just started aiming to eat around 1,600-1,700 calories a day. I’ve read enough of your columns to know that I need to be in a calorie deficit with plenty of protein! But what I’m not sure of is whether I should be eating back the calories from my workouts. I use my FitBit to track my heart rate and calories from my gym sessions and walks, so if it says I’ve burned 300 calories, does that mean I can eat 300 more? I’m new to tracking my calories so am not sure.
– Tracking Slimmer
Congratulations on starting your fitness journey!
Your question is very common and trips a lot of people up. The consensus among every fitness expert I have ever spoken to is no, you should not eat back the calories your trackers says you’ve burned.
Fitness trackers can be inaccurate
A small 2017 study of 60 people by Stanford University suggests that most fitness trackers are inaccurate, overestimating calorie burn by up to 93%.
Apple watches were found to overestimate energy burn by 40%, so if yours says you’ve burned 600 calories, you might actually only have burned 360 calories.
Adding calories back into your diet based on what your fitness tracker says can slow your progress or cause weight gain if it takes you out of a deficit, personal trainer and fat loss coach Anjuli Mack told Insider.
Move away from exercising to burn calories
Thinking of exercise as a means to burn calories isn’t a healthy mindset – you want to find a way of moving that you enjoy or that motivates you for other reasons.
“Focusing on ‘calories burned’ can lead to a negative relationship with food and exercise,” Mack said.
Exercise shouldn’t be punishment for eating or a way to “earn” more food, it should be about empowering yourself, getting stronger and fitter, and boosting your health. That’s how it becomes sustainable.
For me, seeing the weights go up on my lifts keeps me going back to the gym.
Create your calorie deficit with your diet if you want to lose fat, but complement this with workouts (strength-training will help you hold on to muscle and thus lose fat), drinking enough water, and sleeping enough, Mack said.
You burn more energy in your day-to-day life than your workouts
Many people don’t realise that formal exercise only makes up 5-10% of our total daily energy expenditure – we burn far more calories through our daily movements.
Mack points out that a one-hour workout is 4% of your day, so what you do for the remaining 96% matters more.
“Most people sit down to work, commute, sit to eat, chill on the couch for Netflix,” she said. “Get up and get moving when you can.”
And this is where a fitness tracker can be helpful, encouraging you to make healthy choices like taking the stairs or getting off the bus a stop early to hit your step goal – which needn’t be 10,000 steps.
Monitor your progress and adjust accordingly
Sports nutritionist Scott Baptie told Insider you’re never really going to know how many calories you’re burning unless you’re being monitored in a lab, because there are so many personal variables involved.
The key to progress then, is keeping an eye on your results and tweaking accordingly.
“If you’re losing fat then it means you’re in a calorie deficit so consuming fewer calories than you burn,” Baptie said. “If your body fat levels are increasing then it’s the opposite – you’re consuming more calories than you’re burning.”
It’s easy to overestimate how many calories we’re burning, so best not to try.
Mack told Insider it’s best to stay in a calorie deficit for 30 days consistently, and if you don’t see changes in your clothing size or energy levels, make adjustments. Also, use ‘before’ and ‘after’ photos to track your journey, because the scale is a very limited way to measure progress, she said.
Move in ways you enjoy, fuel yourself adequately, and you’ll be on the track to success.
Rachel has a wealth of experience covering fitness, nutrition, and wellness, and she has the hottest experts at her fingertips. She regularly speaks to some of the world’s most knowledgeable and renowned personal trainers, dietitians, and coaches, ensuring she’s always up to date with the latest science-backed facts you need to know to live your happiest and healthiest life.
Read more Working It Out:
- My active social life makes me skip workouts. How do I motivate myself to be consistent again?
- I got so fit working from home. How do I stay in shape and healthy when I return to the office?
- I’m addicted to working out but am scared to cut back. How do I stop over-exercising?
- I gain weight in the winter and end up having to lose 10 to 20 pounds each summer. How do I break this cycle?
- I’ve lost weight and feel good, but I am nervous about ending my diet. How do I avoid regaining weight?