What Should My Macros Be? How to Find Out

Googled "what should my macros be," got seventeen different answers, and now feel more confused than before. That's the standard experience. Everyone has a different calculator, a different formula, and a different opinion on whether 40/30/30 or 30/40/30 is correct.

Here's the reassuring part: the exact numbers matter less than you think, especially at the start. A reasonable starting point that you actually follow will always outperform a perfectly calculated plan you abandon after two weeks. This guide gives you a reasonable starting point.

These are general estimates, not medical prescriptions. If you have a health condition, please work with a registered dietitian.

Why "One Size Fits All" Macros Don't Work

A 5'4" woman who does yoga twice a week and wants to lose 10 lbs has completely different macro needs from a 6'1" man who lifts four times a week and wants to add muscle. Using the same targets would make no sense.

The three variables that change what your macros should be are: your goal, your body weight, and how active you are. Get those three inputs right and the output is a personalised starting point rather than a generic number grabbed from a fitness forum.

What You Need to Know First

Your Goal

Your goal determines how your calories split across macros — and whether you're eating at a deficit, surplus, or maintenance level.

• Fat loss: calorie deficit (300–500 kcal below maintenance), protein prioritised to protect muscle
• Muscle building: calorie surplus (200–300 kcal above maintenance), protein high, carbs filling most of the extra
• Maintenance / general health: eating roughly at maintenance, macros balanced across all three

If you're not sure which goal applies, pick the one that reflects what you actually want to happen to your body over the next three months. Don't optimise for two goals at once — fat loss and muscle building simultaneously is possible but slow, and the nutrition approach is different from both.

Your Weight and Activity Level

Your daily calorie needs — called TDEE, total daily energy expenditure — depend on how much you weigh and how much you move. The most research-validated way to estimate it is the NIH Body Weight Planner, which uses your age, sex, height, weight, and activity level to produce an estimate you can work from.

If you prefer a manual estimate, the Mifflin-St Jeor equation is the most commonly validated formula for most adults:

Basal metabolic rate (BMR):

• Women: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) − 161
• Men: (10 × weight in kg) + (6.25 × height in cm) − (5 × age) + 5

Multiply BMR by an activity factor to get TDEE:

These multipliers, sourced from the Dietary Reference Intakes framework used by the Institute of Medicine, are estimates — individual metabolic rate varies by 200–300 kcal even between people with identical stats. The result is a starting hypothesis, not a precise measurement.

A Simple Way to Calculate Your Macros

Once you have your TDEE, adjust for your goal, then divide into macros.

Step 1: Set your calorie target

• Fat loss: TDEE − 300 to 500 kcal
• Muscle building: TDEE + 200 to 300 kcal
• Maintenance: TDEE (no adjustment)

Step 2: Set your macro split A 30/40/30 split (protein/carbs/fat) is a solid general starting point that works across most goals. For fat loss, shift toward 35/35/30. For muscle building, shift toward 25/45/30.

Step 3: Convert percentages to grams

• Protein grams: (daily calories × protein%) ÷ 4
• Carb grams: (daily calories × carb%) ÷ 4
• Fat grams: (daily calories × fat%) ÷ 9

Also check protein against bodyweight. The Academy of Nutrition and Dietetics supports 1.2–1.6g protein per kg of bodyweight during active weight loss to preserve lean mass. If your calculated protein falls below this range, increase it and reduce carbs slightly.

Step-by-Step Example

Profile: 68kg woman, moderately active, goal is fat loss

BMR: (10 × 68) + (6.25 × 165) − (5 × 30) − 161 = 680 + 1,031 − 150 − 161 = 1,400

TDEE: 1,400 × 1.55 = 2,170 kcal

Calorie target (fat loss): 2,170 − 400 = 1,770 kcal

Macro split (35/35/30 for fat loss):

• Protein: (1,770 × 0.35) ÷ 4 = 155g
• Carbs: (1,770 × 0.35) ÷ 4 = 155g
• Fat: (1,770 × 0.30) ÷ 9 = 59g

Protein bodyweight check: 68kg × 1.4g = 95g minimum. 155g exceeds this — good.

These are the starting targets. Not permanent, not perfect, but enough to begin.

How to Adjust If It's Not Working

Track consistently for two to three weeks before changing anything. Day-to-day weight fluctuates from water retention, salt intake, and hormonal variation — weekly trend is what signals real change.

If you're losing faster than 1.5 lbs per week and feel fatigued: add 100–150 kcal, mostly from protein or complex carbs. The deficit is likely too large.

If nothing is happening after three consistent weeks: reduce calories by 100–150 kcal by trimming carbs slightly. Don't reduce protein.

If you're constantly hungry: check protein distribution. Is most of it at dinner? Spreading protein more evenly across the day reduces hunger significantly without changing your daily total.

If you feel mentally foggy or training performance is dropping: carbs are probably too low. Shift 5% from fat to carbs and reassess.

When to Recalculate

Your TDEE changes as your weight changes. For every 5–10 lbs lost or gained, it's worth recalculating — both because your weight has shifted and because your body adapts metabolically over time.

Also recalculate when: your activity level changes significantly (new job, starting a training programme, injury that reduces movement), or when you shift goals (from fat loss to maintenance, or maintenance to muscle building).

Don't recalculate every week — the noise in short-term data makes weekly adjustments counterproductive. Every six to eight weeks, or when a meaningful change happens, is more useful.

Limitations of Macro Calculators

Okay, I'll admit it — all of this arithmetic produces an estimate, not a measurement. TDEE calculators are validated on population averages, and individual variation is real. Two people with identical stats can have metabolic rates 200–400 kcal apart.

What this means in practice: the calculated numbers are the right place to start. Your body's actual response over two to three weeks of consistent tracking is the right data to act on. If the numbers produce the expected result (roughly 0.5–1 lb/week loss for a fat loss goal), they're accurate for you. If not, adjust based on what you observe.

The other limitation: these calculations assume stable activity levels and consistent food logging. If either of those isn't true — some weeks you train, some weeks you don't; logging is approximate — the numbers become less reliable as anchors. That doesn't mean the approach is wrong; it means the baseline should be revisited more frequently.

And this approach doesn't suit everyone equally. People with medical conditions affecting metabolism — thyroid disorders, insulin resistance, PCOS — may find that standard calculator outputs don't reflect their actual needs. If you're in that situation and the numbers consistently don't produce expected results after genuine effort, working with a registered dietitian is worth the investment.

Try It Without the Arithmetic

Once you have your targets, the next challenge is planning meals that actually hit them. At Macaron, we built our AI to plan meals around your macro targets and remember your numbers across conversations — so you're not recalculating every day. Try it free and plan this week before Monday starts.

FAQ

Should I Use a Macro Calculator App?

Yes, for convenience — apps automate the TDEE calculation and convert percentages to grams instantly. Most also let you adjust and recalculate easily. The NIH Body Weight Planner is the most research-backed free option. MacroFactor is worth noting for its adaptive TDEE calculation that adjusts based on real-world weight data over time, rather than a fixed formula.

The formula matters less than the consistency of applying it. Any well-built calculator will get you to a reasonable starting point.

How Often Should I Update My Macros?

Every six to eight weeks, or when your weight has changed by 5–10 lbs, or when your activity level shifts significantly. Recalculating more often than this introduces more noise than signal — short-term weight fluctuation doesn't indicate that your targets are wrong.

My Macros Feel Too Restrictive — What Do I Do?

First, check whether you've set an aggressive deficit. A 700+ kcal deficit feels restrictive because it is — and it's also harder to sustain. Reduce the deficit to 300–400 kcal and see if adherence improves.

Second, check protein distribution. If most protein is concentrated in one meal, hunger patterns through the day become uneven. Spreading protein more evenly across three meals tends to feel less restrictive even at identical calorie totals.

Third, consider whether macro tracking is the right tool for you right now. Some people do better starting with a simpler approach — just eating mostly whole foods and adding a serving of protein to every meal — before introducing precise tracking. Turns out simpler systems with higher adherence often produce better real-world results than precise systems followed intermittently.

Related Reading

• How to Track Macros — once you have targets, how to actually log them
• How to Count Macros — practical step-by-step logging guide
• Macros for Weight Loss — macro splits specifically for fat loss
• Macro Meal Planner — tools that build meals around your targets
• Meal Planner Based on Calories — when calorie-first planning fits better

TDEE calculation uses Mifflin-St Jeor equation and activity multipliers from Institute of Medicine Dietary Reference Intakes. Protein targets referenced from Academy of Nutrition and Dietetics position statement. NIH Body Weight Planner provides validated online TDEE estimation. General dietary reference — not personalised medical advice.