Are you supposed to eat back the calories you burn?
Unpopular opinion: we donβt recommend integrating your wearable with your macro tracker.
A top question from our trackers...
βShould I eat back the calories from my fitness tracker?β
Letβs walk through why thatβs one of the most common mistakes we see for those newer to tracking their food, and what to do instead.
Yes, even if you love your Garmin (we do too).
Hereβs where macro tracking apps go wrong
When you first download a calorie counting app, many of them put you through this process π
1οΈβ£ Use your height, weight, age, + sex to estimate your BMR (BMR = Basal Metabolic Rate, the amount of calories you need to just exist)
2οΈβ£ Layer on a vague βactivity factorβ to guess your needs
3οΈβ£ Ask you to sync your Apple Watch, Garmin, or Fitbit
4οΈβ£ Adjust your daily calorie target in real time based on your βcalories burnedβ as calculated from your wearable
On paper, it sounds perfect, but in reality, weβre multi-layering systems with large margins of error that are more likely to do more harm than good.
The problem with calculating BMR:
BMR estimates arenβt reliable at the individual level.
Even the best BMR formulas (like Mifflin-St. Jeor or Cunningham) come with a ~Β±400 calorie margin of error*.
Meaning: if the calculator βsaysβ your BMR is 1,500 calories, what it really means, is that 95% of people with your same stats have a BMR of between 1,100 and 1,900 calories.
That means your βcalculatedβ targets could be off by a full meal before we even layer on activity modifiers.
*https://doi.org/10.1016/j.jand.2016.03.018
The problem with Activity Tracker calories burned:
Your trackerβs calorie-burning data is probably wrong.
A 2022 review of wearables (Garmin, Fitbit, and Apple Watch) resulted in the following outcomes:
Heart rate accuracy can be decent
Steps counts are accurate
Energy expenditure accuracy can be off by greater than 30% in the best case scenario
The researchers concluded:
βNone of the tested devices proved to be accurate in measuring energy expenditure.β
*PMID: 35060915
Tie the problems together:
So now that we know that the initial BMR equation can be off by 400 calories, why would we layer on an inconsistent calorie burn from a wearable?
If we combine the margin of error from both circumstances:
We can get a calorie target that could be 500+ calories off from where your maintenance needs actually are π΅βπ«
And these are just the quantitative issues.
Even if youβre one of the lucky ones where it is pretty accurate for you, here are three more reasons not to set your targets using your wearable data π
Problem #3: Rest Days
Rest days donβt register as activity. Which means if youβre using an AI tracking app, it will drop your calorie target exactly when you need it most.
This discourages fueling on recovery days, when you need additional energy to:
Replenish glycogen
Support muscle repair
Reduce fatigue & DOMS
Actually make progress from your training
Chronically under-fueling on rest days can slow muscle recovery, reduce training capacity, and increase injury risk.
(See our βShould I Eat Less on Rest Daysβ post from July 22nd for more on this.)
Problem #4: Planning ahead
When your calorie target changes based on what youβve burned, you donβt actually know how much youβll be βallowedβ to eat until the day is over.
That makes it almost impossible to:
Build a consistent eating pattern
Create a meal blueprint that works for your lifestyle
Prep food ahead of time without wasting or running short
Instead, you end up playing macro Tetris at 9 p.m., scrambling to make your calories fit your end-of-day calorie burn. Which is stressful, inconsistent, and not sustainable long-term.
Problem #5: Psychological impact
And finally, but most importantly, the psychological impact of letting your activity dictate your day-to-day intake:
β βIf I donβt burn, I donβt earn.β
β βIf I move more, I can eat more.β
This creates a transactional relationship with food and movement. Which can spiral into:
Overtraining
Guilt on low-step days
Compensatory exercise
Fear of taking rest days
Thatβs not structure or balancing taking care of your body.
Hereβs what we recommend instead:
Rather than adjusting your daily calories based on βburnedβ estimates, set a consistent target range and let your weight trends results guide adjustments.
Choose a calorie range that gives you about 200 calories of flexibility.
Track your intake and your weight for 3-4 weeks.
Make small adjustments based on the trend in your data, not what your watch says you burned.
We created a 15-page guide that explains exactly how to find and manage your maintenance calories, the same method we use in our coaching cohorts.
