What are macros? Protein, carbs and fat explained
Macros are protein, carbohydrate and fat, the nutrients that supply calories. Calories per gram, what each one does, and how people set their daily targets.
What are macros?
Macros, short for macronutrients, are the three nutrients your body needs in large amounts and gets energy from: protein, carbohydrate and fat. Protein and carbohydrate supply about 4 kcal per gram, fat about 9. Alcohol supplies 7 kcal per gram but is not a nutrient you need. Fiber is a type of carbohydrate. Tracking macros means counting grams of each.
How to set macro targets
- Start from a calorie targetEstimate your maintenance calories, then add or subtract for your goal. Macros split that number; they do not replace it.
- Set protein firstMultiply your body weight in kg by a protein figure, from 0.8 g/kg for general health up to about 1.6–2.2 g/kg if you lift.
- Set fat nextGive fat 20–35% of your calories, the range in the US Dietary Reference Intakes, and divide those calories by 9 for grams.
- Give carbohydrate the restSubtract protein and fat calories from the total, then divide what remains by 4 for grams of carbohydrate.
- Adjust from resultsKeep the targets for a few weeks, then adjust based on your weight trend, your training and how full you feel.
Calories tell you how much energy a meal holds. Macros tell you where it comes from. Two meals at 600 kcal can be very different: one a chicken and rice bowl with 45 g of protein, the other a pastry and a sweet coffee with a fraction of that. The difference matters for fullness, for training, and for keeping muscle when you eat less.
The macronutrients at a glance
| Macro | kcal per gram | Main job | Common sources |
|---|---|---|---|
| Protein | 4 | Builds and repairs muscle, organs, enzymes and hormones; the most filling per calorie | Meat, fish, eggs, dairy, tofu, tempeh, beans, lentils |
| Carbohydrate | 4 | Main fuel for hard exercise and the brain; stored as glycogen in muscle and liver | Rice, bread, pasta, oats, potatoes, fruit, beans |
| Fat | 9 | Long-term energy store; needed for hormones, cell membranes and absorbing vitamins A, D, E and K | Oils, butter, nuts, seeds, avocado, cheese, fatty fish |
| Fiber (a carbohydrate) | About 2 on average | Adds bulk, slows digestion, feeds gut bacteria | Beans, lentils, whole grains, vegetables, fruit, nuts |
| Alcohol | 7 | Not a nutrient; supplies energy the body burns off first | Beer, wine, spirits |
The 4-4-9 figures are the Atwater factors, worked out more than a century ago and still used on food labels. They are averages. Real foods vary a little, and the body does not absorb every calorie it eats, especially from whole nuts and high-fiber foods.
Each macro in practice
The US Dietary Reference Intakes set broad ranges for adults: 10–35% of calories from protein, 45–65% from carbohydrate and 20–35% from fat. Within those ranges, each macro has its own logic.
- Protein: The adult RDA is 0.8 g per kg of body weight, enough to avoid deficiency in most people. People who train usually do better with more. The ISSN position stand (2017) suggests 1.4–2.0 g/kg for most people who exercise, and a 2018 meta-analysis by Morton and colleagues found gains from lifting leveled off around 1.6 g/kg on average, with some people benefiting up to about 2.2. The protein calculator gives a range for your weight.
- Carbohydrate: The US RDA is 130 g a day, based on the brain’s glucose needs. Hard training sessions run largely on it. Most people find a mix of grains, fruit, vegetables and beans easier to sustain than very low-carb eating.
- Fat: Very low fat makes it hard to absorb fat-soluble vitamins and get essential fatty acids. The Dietary Guidelines for Americans advise keeping saturated fat under 10% of calories.
- Alcohol: At 7 kcal per gram, a standard US drink with 14 g of alcohol carries about 98 kcal before any mixer or the carbs in beer and wine. It counts toward calories but toward no macro target.
- Fiber: Counted inside total carbohydrate on US labels, and listed separately at 2 kcal per gram on EU labels. “Net carbs” subtracts fiber from total carbs, but the term has no official US definition. Dietary fiber has its own page.
A worked example
Read a meal by its macros. A bowl with 40 g of protein, 60 g of carbs and 15 g of fat holds (40 × 4) + (60 × 4) + (15 × 9) = 160 + 240 + 135 = 535 kcal. Protein supplies 30% of that, carbs 45% and fat 25%.
Now set a day. Someone who weighs 70 kg and eats 2,200 kcal picks 1.6 g/kg of protein: 112 g, or 448 kcal. Fat at 30% of calories is 660 kcal, or about 73 g. That leaves 2,200 − 448 − 660 = 1,092 kcal for carbohydrate, which is 273 g. The day reads 112 g protein, 73 g fat and 273 g carbs. The macro calculator does the same split for your body and goal.
Choosing a split
There is no single correct split. In controlled studies that match calories and protein, diets that lean on carbs or on fat produce similar fat loss. In the DIETFITS trial (2018), people on a healthy low-fat diet and a healthy low-carb diet lost similar weight over a year. Choose the one you can keep.
you want a default that fits most people: protein set by body weight, fat around 30% of calories, carbs with the rest.
you are in a deficit or lifting hard and want to protect muscle and stay fuller on fewer calories.
you prefer more fat in your meals and most of your training is easy to moderate; total calories still decide weight change.
Common mistakes
- Chasing exact grams: Landing within 10–20 g of your protein target is plenty. Food labels carry their own error.
- Forgetting cooking fat: A tablespoon of oil is about 14 g of fat, roughly 120 kcal, and it rarely makes it into the log.
- Ignoring drinks: Alcohol adds energy without counting toward any macro, so a day can look on target and still be over.
- Treating carbs as the enemy: Weight change follows total calories. Cutting carbs works when it cuts calories.
How FORM uses it
FORM sets protein at 2.0 g per kg for muscle goals, fat at about 25% of energy and carbs with the rest, and every target is editable. Each meal you log by photo, barcode, menu or text lands as calories, protein, carbs, fat and fiber in the macro tracker, next to your targets. Alcohol, water and caffeine have their own logs, so drinks are part of the day’s picture.
FAQ
Should I count macros or just calories?
Calories decide weight change. Macros shape what that weight is made of and how full you feel. If you track only one macro, make it protein.
What is a good macro split for weight loss?
There is no single best split. Keep protein high, around 1.6 g per kg or more, fat at 20–35% of calories, and fill the rest with carbohydrate, then judge by results.
Is fiber included in carbs?
Yes, fiber is a carbohydrate. On US labels it sits inside total carbohydrate; on EU labels it is listed separately.
How many calories are in a gram of alcohol?
About 7 kcal, nearly as much as fat. A standard US drink with 14 g of alcohol holds about 98 kcal before mixers.
Are macros the same as micronutrients?
No. Macros supply energy and are eaten in grams. Micronutrients, the vitamins and minerals, are needed in milligrams or micrograms and supply no calories.