How to set your macros for fat loss or muscle gain

2026-10-10 · Zefro

Calories decide whether you lose or gain. Macros decide what that weight is made of. Set them in this order.

Why this order

Each step depends on the one before. Calories set the budget. Protein and fat each have a job that a fixed amount covers, so they are set next. Carbs are the flexible part, so they take whatever is left. Do it the other way round and a fixed carb number can push protein below what you need.

Macros are counted in grams but paid for in calories. Protein and carbs have 4 kcal per gram, fat 9. These are the general Atwater factors, and every sum below uses them.

1. Calories

Start from your TDEE, the calories you burn in a day. How many calories do you burn in a day? walks through it. To lose about 0.5 kg a week, eat 550 kcal below it. To gain about 0.25 kg a week, eat 275 above.

Those numbers come from a rule of thumb: about 7,700 kcal per kilogram of body weight. Spread 0.5 kg over a week and you get 0.5 × 7,700 ÷ 7 = 550 kcal a day. Half that pace gives 275. In the app you pick the pace: 0.25, 0.5 or 0.75 kg a week to lose, 0.25 or 0.5 to gain. Each 0.25 kg step moves your target by 275 kcal a day.

The rule is a starting point, not a promise. A 2008 analysis by Kevin Hall found that the energy in each kilogram you lose depends on how much body fat you start with, so the scale will not follow the arithmetic exactly. Weigh yourself regularly and adjust by what actually happens.

How fast is sensible? A review of contest preparation by Helms and colleagues suggests losing about 0.5 to 1 percent of body weight a week. For an 80 kg person that is 0.4 to 0.8 kg. For gaining, a review of off-season bodybuilding nutrition by Iraki and colleagues suggests a surplus of about 10 to 20 percent and a gain of about 0.25 to 0.5 percent of body weight a week for beginners and intermediates.

2. Protein

1.8 grams per kilogram of body weight when losing or gaining, 1.6 to maintain. It is capped at 35 percent of your calories so it never crowds out everything else.

The International Society of Sports Nutrition says 1.4 to 2.0 g per kg a day is enough for most people who exercise. A meta-analysis of 49 trials by Morton and colleagues found that protein beyond about 1.62 g per kg a day added no further gains in fat-free mass from resistance training. The maintenance figure of 1.6 sits right there.

When calories are cut, the case for more grows. The same position stand says resistance-trained people in a deficit may need 2.3 to 3.1 g per kg to keep the most lean mass. Zefro's 1.8 is a moderate step up, not the top of that range.

The 35 percent cap matches the top of the adult range for protein in the US Dietary Reference Intakes, which is 10 to 35 percent of calories.

3. Fat

25 percent of calories, and never below 0.5 g per kg.

The same reference intakes give adults a range of 20 to 35 percent of calories from fat, so 25 percent sits inside it. The floor matches the bottom of the 0.5 to 1.5 g per kg range in the off-season review. It only decides the number when calories are low and body weight is high, as the third example shows.

4. Carbs fill the rest

Protein and carbs have 4 kcal per gram, fat 9. Take protein and fat calories away from your total and divide what is left by 4.

Carbs fuel hard training. The off-season review suggests at least 3 to 5 g per kg a day to support the energy demands of resistance training. If protein and fat ever add up to more than your total, Zefro lowers fat toward its floor first, then protein, and carbs stop at zero. A macro is never negative.

A worked example

An 80 kg person with a TDEE of 2,759 who wants to lose fat eats 2,209 kcal. Protein: 1.8 × 80 = 144 g (576 kcal). Fat: 25 percent of 2,209 = 552 kcal, about 61 g. Carbs: the remaining 1,081 kcal, about 270 g.

Check the sum: 576 + 552 + 1,081 = 2,209. As shares of calories that is about 26 percent protein, 25 percent fat and 49 percent carbs. The carb share also sits inside the reference range of 45 to 65 percent.

The same person gaining

To gain about 0.25 kg a week, the same person eats 2,759 + 275 = 3,034 kcal, a surplus of about 10 percent. Protein stays at 144 g (576 kcal). Fat: 25 percent of 3,034 = 758.5 kcal, about 84 g. Carbs: 3,034 − 576 − 758.5 = 1,699.5 kcal, about 425 g, or 5.3 g per kg.

At maintenance, 2,759 kcal, protein drops to 1.6 × 80 = 128 g. Fat comes to about 77 g and carbs to about 389 g.

When the limits decide

Take someone who weighs 120 kg with a TDEE of about 2,319, losing 0.5 kg a week: 2,319 − 550 = 1,769 kcal.

• Protein: 1.8 × 120 = 216 g, or 864 kcal. That is more than 35 percent of 1,769, which is 619 kcal. Protein is held at 619 kcal, about 155 g.
• Fat: 25 percent of 1,769 is 442 kcal, about 49 g. The floor is 0.5 × 120 = 60 g, so fat is 60 g (540 kcal).
• Carbs: 1,769 − 619 − 540 = 610 kcal, about 152 g.

When the cap sets protein, Zefro tells you so on the summary screen at the end of setup instead of changing the number quietly. Helms and colleagues give their dieting range per kilogram of lean body mass, not total weight, which is worth knowing if much of your weight is fat.

Common mistakes

• Setting carbs first. Protein and fat get squeezed. Keep the order.
• Forgetting that fat is 9 kcal per gram. A gram of fat carries more than twice the calories of a gram of protein or carbs. Oil, butter and nuts add up fast. Log them.
• Never updating. Your TDEE is worked out from your weight. After a real change, run the numbers again.
• Judging by one weigh-in. Look at the trend over two weeks or more before you change calories.
• Cutting fat to almost nothing to save calories. Keep it at or above the floor.

Who this suits and who it does not

It suits adults who train and want to lose fat, hold their weight or build muscle, and who are happy to log food.

It is not for everyone. If you have a medical condition, or a doctor or dietitian has given you different targets, follow them. The ISSN position stand notes that people with kidney failure benefit from protein-restricted diets, so these protein numbers are not for them.

Practical steps

1. Work out your TDEE in the TDEE calculator.
2. Choose to lose, maintain or gain, and a pace.
3. Run the macro calculator, or let Zefro set the same numbers when you set up the app.
4. Log your food and weigh yourself for two weeks.
5. If the trend is off, move calories by one 275 kcal step and keep protein where it is.
6. Pair the diet with training that keeps asking a little more. Progressive overload explains how.

Questions

Do I have to hit my macros exactly? No. Treat them as daily targets to get close to. The trend over weeks is what shows on the scale.

Is 1.8 g of protein per kg a lot? It sits inside the ISSN range of 1.4 to 2.0 g per kg for people who exercise. The position stand reports that studies of healthy, resistance-trained adults eating more than that found no harmful effects on kidney or liver function.

How should I spread protein over the day? The ISSN suggests about 0.25 g per kg per meal, or 20 to 40 g, every 3 to 4 hours. 144 g over four meals is 36 g each.

Can I eat more carbs and less fat? Yes. In Zefro you can change calories and each macro yourself, in grams or percent, on the nutrition targets screen. Keeping fat within 20 to 35 percent of calories stays inside the reference range.

What is the difference between a deficit and a surplus? A calorie deficit means eating below your TDEE, a calorie surplus means eating above it.

The macro calculator runs the same numbers. Zefro applies them for you and shows your day against them when you log food. Meal and macro terms are in the glossary.