2026-05-08 · Dr. Naomi Vargas

Macros 101: why they matter and how to calculate your ratio

Before you pick a tracker, you need a target. A practical guide to what macronutrients do, why ratios matter more than calories alone, and how to set yours.

Most people who start tracking food open an app, accept the default target, and miss the most important step: deciding what their target should actually be.

Calories alone are not enough. Two diets at 2,000 kcal can produce radically different outcomes — one builds muscle, the other strips it; one stabilises blood sugar, the other spikes it. The difference is macronutrient ratio: how those calories split between protein, carbohydrate, and fat.

This is the 10-minute version of what you need to know before you pick a tracker.

Why macronutrients matter

A calorie is a unit of heat. Your body does not treat all calories identically.

Protein builds and repairs tissue, has the highest thermic effect (you burn ~25% of its calories just digesting it), and is the single biggest predictor of whether you keep muscle while losing fat.
Carbohydrate is your fastest-access fuel. It restocks glycogen for hard training and drives high-intensity output. Type and timing matter more than total amount for most people.
Fat runs your hormones, helps absorb fat-soluble vitamins (A, D, E, K), and is the default fuel at rest and at low intensity.

Get the ratio right and your body composition, training, energy, and recovery all improve at the same total calorie intake. Get it wrong and you can be in a “perfect” calorie deficit while losing muscle, missing micronutrients, and feeling terrible.

The International Society of Sports Nutrition’s position stand on protein is the most-cited summary if you want the underlying evidence.

What a macro ratio actually is

A macro ratio expresses the percentage of your daily calories that come from each macronutrient.

Common ratios you will see:

Ratio (P/C/F)	Typical use case
30 / 40 / 30	Balanced — general health, mixed training
40 / 40 / 20	Lean bulk or recomposition
40 / 30 / 30	Fat loss with strength training
25 / 50 / 25	Endurance athletes
30 / 5 / 65	Ketogenic
20 / 60 / 20	Higher-carb plant-based

The ratio is a starting point, not a prescription. The way you use it: pick a ratio that matches your goal, convert it to grams, then adjust over six to eight weeks based on what actually happens.

“The biggest mistake new trackers make is treating their starting ratio as if it were handed down on a tablet. It is a hypothesis. Test it for six weeks. Adjust.” — Dr. Naomi Vargas

How to calculate your macro ratio

Five steps. None of them require an app — though by step five you will want one.

Step 1 — Estimate your maintenance calories

Maintenance is the calorie intake at which your weight is stable. The cleanest way to find it is to log honestly for two weeks and watch the scale; the fastest way is to estimate.

A reasonable starting estimate, the Mifflin–St Jeor equation, multiplied by an activity factor (1.2 sedentary → 1.9 hard daily training):

Men:   BMR = 10 × kg + 6.25 × cm − 5 × age + 5
Women: BMR = 10 × kg + 6.25 × cm − 5 × age − 161
Maintenance = BMR × activity factor

If you would rather skip the arithmetic, Examine.com’s calorie calculator or TDEE Calculator will do it for you. Treat the result as a hypothesis to refine, not a fact.

Step 2 — Pick a calorie target based on your goal

Maintenance: maintenance × 1.0
Fat loss: maintenance × 0.80 to 0.85 (a 15–20% deficit is sustainable; more is not)
Lean gain: maintenance × 1.05 to 1.10 (a small surplus; more becomes fat)
Recomposition: maintenance × 0.95 to 1.00, with a high protein floor

For more on deficit sizing, Stronger By Science on dieting is the best lay-accessible source.

Step 3 — Set your protein floor in grams

Protein is the macro you set in grams first, not as a percentage. The evidence-based range:

Sedentary or light activity: 1.2–1.6 g per kg of body weight
Strength training, fat loss, or GLP-1 therapy: 1.6–2.2 g/kg
Aggressive cut or contest prep: 2.2–2.6 g/kg
Older adults (>60): at least 1.6 g/kg to preserve muscle

For an 80 kg adult lifting four days a week and trying to lose fat, that lands around 160–180 g of protein daily. Multiply grams by 4 to get calories: 160 × 4 = 640 kcal from protein.

Step 4 — Choose a fat floor

Fat below ~0.6 g/kg starts to compromise hormones over time. A sensible floor is 0.7–1.0 g/kg. For an 80 kg adult: 60–80 g of fat, or 540–720 kcal.

If you are running a ketogenic ratio, you skip this step — fat becomes whatever calories are left after protein.

Step 5 — Fill the rest with carbohydrate

Subtract protein calories and fat calories from your total. Divide by 4 (calories per gram of carbohydrate). That is your daily carbohydrate target.

Worked example. 80 kg adult, mixed training, fat-loss goal:

Maintenance: ~2,650 kcal → fat-loss target: 2,250 kcal
Protein: 1.8 g/kg × 80 = 144 g → 576 kcal
Fat: 0.8 g/kg × 80 = 64 g → 576 kcal
Carbs: (2,250 − 576 − 576) / 4 = 274 g

Starting macros: 144 P / 274 C / 64 F, ratio ~26 / 49 / 25.

That number is now your hypothesis. Use a tracker to test it.

Where a tracker comes in

You can keep all this in a spreadsheet. But the apps in our 2026 benchmark automate the part that actually decides whether you stick to a plan: the per-meal logging.

The five categories you should probably look at first:

Best for weight loss — if your goal is a sustainable deficit.
Best for muscle gain — if you are running a lean bulk.
Best for GLP-1 users — if your appetite signal is suppressed by medication.
Best for keto — if you are running a very-low-carb ratio.
Best for beginners — if you have never tracked before.

The full leaderboard lives on the rankings page.

Common mistakes to avoid

Treating the calculator’s number as the truth. Equations are hypotheses. Adjust based on what the scale and the mirror actually do over six to eight weeks.
Setting protein as a percentage instead of grams. A 20% protein target at 1,400 kcal is not the same as 20% at 2,800 kcal — one of them will lose you muscle.
Cutting fat below 0.5 g/kg. This compromises hormones long-term, and the calorie savings are not worth it.
Aiming for perfect adherence every day. Weekly averages matter more than any single day. A tracker that lets you see the seven-day trend is doing the right job.
Switching ratios every week. Pick one. Run it for six weeks. Then adjust.