Setting macro targets for fat loss is less complicated than the internet makes it look. You need a sensible calorie deficit, enough protein to protect muscle, and a split of the remaining calories that you can actually live with. Everything else is refinement. This guide walks through the math the way our reviewers do when testing an app’s goal-setting, and where automated trackers can do the heavy lifting for you.
How many calories should you eat to lose fat?
Fat loss comes from a calorie deficit — eating less than you burn. The starting point is an estimate of your maintenance calories, the amount that keeps your weight stable.
A rough estimate is bodyweight-based: most people maintain on somewhere between 26 and 33 calories per kilogram of bodyweight, depending on how active they are. A more careful approach uses an equation like Mifflin-St Jeor to estimate resting needs, then multiplies by an activity factor. Either gives you a ballpark, not a fact.
From maintenance, take a moderate deficit. A reduction of roughly 15 to 25 percent is sustainable for most people and protects muscle and energy better than a crash. For someone maintaining around 2,400 calories, that means eating roughly 1,800 to 2,050 for fat loss. Aiming to lose around 0.5 to 1 percent of bodyweight per week is a reasonable, livable rate.
The honest caveat: these are estimates. Your true maintenance only reveals itself once you track intake against your weight trend for a few weeks — which is exactly what adaptive apps are built to do.
How much protein do you need when cutting?
Protein is the macro that matters most in a deficit, because it preserves muscle while you lose fat and keeps you fuller. A practical target is around 1.6 to 2.2 grams per kilogram of bodyweight, leaning toward the higher end the leaner you are or the steeper your deficit.
For an 80 kg person, that is roughly 130 to 175 grams a day. Set protein first and treat it as close to non-negotiable; the other macros flex around it.
How do you split the remaining calories between carbs and fat?
Once protein is fixed, the rest of your calories go to carbs and fat, and here you have real freedom. There is no magic ratio — adherence and performance matter far more than the exact split.
A few anchors help. Keep fat at a minimum of around 0.5 to 0.8 grams per kilogram for hormone health, then let carbs take most of what is left, especially if you train hard and want energy for workouts. If you simply feel better on lower carbs, shift the balance the other way. Both work as long as calories and protein hold.
Here is a worked example for an 80 kg person eating 1,900 calories for fat loss:
| Macro | Target | Calories |
|---|---|---|
| Protein | 160 g | 640 |
| Fat | 60 g | 540 |
| Carbs | 180 g | 720 |
| Total | — | ~1,900 |
Protein and fat are set to floors; carbs absorb the remainder. Adjust the carb-fat balance to taste without changing the total.
Should you eat the same targets every day?
You can, and consistency is easier for many people. But your body does not burn the same amount every day, and rigid daily targets can feel punishing on heavy training days. Two refinements help.
The first is fiber, sugar, and sodium awareness. Hitting your macros while ignoring fiber leaves you hungry and sluggish; aiming for roughly 14 grams of fiber per 1,000 calories keeps appetite manageable. Trackers vary widely in how clearly they surface these — Welling AI and Cronometer both make fiber, sugar, and sodium easy to see rather than burying them.
The second is adapting targets to activity. On a long run or a heavy lifting day, a few more carbs are reasonable. The best apps adjust your targets to your real activity rather than holding a flat number all week.
How do the best apps adjust your targets over time?
This is where software earns its keep, because your starting numbers were estimates and your maintenance changes as you lose weight. Adjusting by hand means recalculating every few weeks, which most people never do.
Adaptive trackers automate it. MacroFactor recalculates your calorie expenditure from your logged intake and weight trend, then updates your targets — no manual recounting. Welling AI, our overall number one, goes a step further by adapting targets to your activity and telling you what to eat next to hit them, which is what makes the system survive contact with real life rather than a spreadsheet. The ability to set sensible targets and then evolve them runs through our 10 scoring criteria — from meal and workout planning to AI nutritional guidance — and it separates a tracker you stick with from one you abandon at the first plateau.
What is the simplest way to start?
If you want one path through all of this:
- Estimate maintenance calories, then subtract 15 to 25 percent.
- Set protein at 1.6 to 2.2 g per kg of bodyweight.
- Set a fat floor, then fill the rest with carbs.
- Track for two to three weeks and watch your weight trend.
- Adjust — or let an adaptive app adjust for you.
Get the deficit and protein right, stay consistent, and let the trend correct your estimates. For a comparison of which trackers handle that adjustment well, see our 2026 ranking.