An adaptive TDEE that keeps up with your real data
A TDEE calculator gives you a starting estimate from your age, height, weight and activity level. It is a good first guess, but it cannot know how your body actually responds. Fiytt starts from an estimate and then adjusts your total daily energy expenditure (TDEE) as your logged data changes, so your calorie target follows what is really happening rather than what a formula predicted on day one.
Why a fixed TDEE drifts
Activity guesses are rough
Most people pick the wrong activity factor. The gap between sedentary (×1.2) and moderately active (×1.55) is several hundred calories a day.
Your body changes
As you lose or gain weight, the energy you burn changes too. A target set months ago slowly stops matching.
Life changes
A new job, a training block or an injury changes how much you move. An adaptive estimate corrects for all three by looking at your own data over time.
How it works in Fiytt
1Start with an estimate
Fiytt sets a starting TDEE from your profile. You can check the maths with the free BMR and TDEE calculator.
2Log as you normally would
Track meals against your calorie and macro targets and weigh in regularly. Logging happens in the iOS and Android apps.
3Let the estimate adjust
As your weight trend and intake build up, Fiytt updates your daily energy expenditure estimate.
4Keep targets in step
Use the updated estimate to set calorie and macro targets for maintenance, fat loss or muscle gain, with quick presets.
Built-in safety defaults
Fiytt keeps calorie floors in place and does not set automatic calorie targets for minors, during pregnancy or for people with a history of eating disorders. If any of those apply to you, work with a qualified professional.
Pairs well with
Weight trend charts
See the trend line rather than day-to-day noise.
Macro targets with presets
Set targets yourself, or let a coach set training, rest and refeed day macros.
Habit targets
Track steps, water and sleep, which all affect how much energy you use.
Frequently asked questions
What is adaptive TDEE?
It is an estimate of the calories you burn each day that updates from your own logged intake and weight trend, instead of staying fixed at a formula's first guess.
How is it different from a TDEE calculator?
A calculator multiplies your BMR by an activity factor once. An adaptive TDEE keeps adjusting as your data comes in, so it can correct a wrong activity guess.
How long does it take to adjust?
It needs a few weeks of regular food logging and weigh-ins. The more consistently you log, the more useful the estimate becomes.
Is Fiytt free?
Fiytt has a free tier. Free iOS users see ads; Premium removes them and unlocks more features.
One app instead of three
Log workouts and meals, bring in your runs, get AI plans and add a certified coach when you want one. Free to start on iPhone, Android and Apple Watch.
Last reviewed October 16, 2026.