Macronutrients: what they are, how much you need and macros per 100 g

What macronutrients are

Macronutrients are the three nutrients you eat in amounts of grams and that supply the energy in your diet: protein, carbohydrate (carbs) and fat. They are called "macro" because you need them in grams, unlike micronutrients (vitamins and minerals), which are measured in milligrams or micrograms. Fibre is a type of carbohydrate that is barely digested, and alcohol provides energy but is not a nutrient you need. Water does not count: it has no calories.

For weight loss, total calories matter most. In the POUNDS LOST trial (Sacks et al., NEJM 2009), 811 overweight adults followed one of four diets with different splits for two years (35% to 65% carbohydrate, 20% to 40% fat and 15% to 25% protein), and weight loss was similar on all of them: after two years, 2.9 kg on 65% carbohydrate and 3.4 kg on 35%. The split does matter for other things: protein affects the muscle you build or keep if you train, and fibre and the type of fat affect long-term health.

How many calories each macronutrient provides

The calories on a label are not measured by burning the food: they are calculated by multiplying the grams of each macronutrient by a fixed factor. In the European Union those factors are set by Annex XIV of Regulation 1169/2011, and they are the same as the general Atwater factors described by the FAO. Fibre counts as 2 kcal per gram because it is not digested in the small intestine and only part of it is fermented in the colon. That is why 10 g of oil adds 90 kcal and 10 g of sugar adds 40.

Protein: the one that builds and repairs

Protein is made of amino acids. The proteins in your body use 20 of them, and 9 are essential: you cannot make them, so they have to come from food. With them you repair muscle after exercise, make enzymes, hormones and antibodies, and renew skin, hair and nails. Animal sources (meat, fish, eggs, dairy) bring all 9 essential amino acids in good proportions; legumes, grains and nuts also provide protein, and combining them over the day completes the profile.

How much protein you need

The EFSA reference intake for adults is 0.83 g per kg of body weight a day, a figure that covers the needs of 97.5% of healthy people. It is a floor so you do not fall short, not a target for building muscle:

• If you do not train: 0.83 g/kg (EFSA). At 70 kg, 58 g a day
• If you do strength training: around 1.6 g/kg. In the Morton et al. meta-analysis (BJSM 2018; 49 trials, 1,863 participants), there was no further gain in lean mass above 1.62 g/kg, with a confidence interval reaching 2.2 g/kg. At 70 kg, 112 g a day
• In a calorie deficit and over 65 the numbers change: you will find them with their sources in how much protein you need per day
• If you have kidney disease, the amount is for your doctor to decide

Protein sources, with USDA data

Protein and calories per 100 g according to USDA FoodData Central (SR Legacy), with the record number so you can check it:

• Roast chicken breast, skinless: 31 g protein and 165 kcal (FDC 171477)
• Light tuna canned in water, drained: 25.5 g and 116 kcal (FDC 171986)
• Farmed salmon, cooked: 22.1 g and 206 kcal, with 12.4 g fat (FDC 175168)
• Firm tofu (set with calcium sulphate): 17.3 g and 144 kcal (FDC 172475)
• Whole egg, raw: 12.6 g and 143 kcal (FDC 171287); egg white alone, 10.9 g and 52 kcal (FDC 172183)
• Non-fat Greek yogurt: 10.2 g and 59 kcal (FDC 170894). Note: an ordinary plain yogurt has 3.5 g (FDC 171284)
• Boiled lentils: 9.0 g and 116 kcal, with 7.9 g fibre (FDC 172421)

Carbohydrate: sugars, starch and fibre

Carbohydrates are sugars (those in fruit, milk or table sugar), starch (grains, potatoes, legumes) and fibre. The first two are digested down to glucose and other simple sugars that the body uses as fuel: the brain relies mainly on glucose, and muscle burns it quickly during intense exercise. EFSA puts carbohydrate intake at 45-60% of energy for adults and children; on 2,000 kcal, between 225 and 300 g a day.

Quality matters more than "simple or complex"

Fibre is the part of carbohydrate with the strongest evidence. EFSA considers 25 g a day adequate for normal bowel function in adults, and in the series of reviews by Reynolds et al. (Lancet 2019; 185 prospective studies and 58 clinical trials), the largest reduction in the risk of death, coronary heart disease, stroke, type 2 diabetes and colorectal cancer was seen with 25-29 g of fibre a day. In the same review, the glycaemic index showed a link with health of low or very low certainty, weaker than that of fibre or whole grains; if you want to understand it properly, it is in the glycemic index explained.

• More fibre: legumes (7.9 g per 100 g of boiled lentils), oats (10.1 g per 100 g dry), whole fruit and vegetables
• Whole grains instead of refined ones when you can: that is the other recommendation that comes out of Reynolds et al.
• Sugars: those in whole fruit come with fibre and water; those in soft drinks and juices come without them, and large amounts go down without you noticing

Fat: 9 kcal per gram, and not all the same

Fat is the most concentrated form of energy: 9 kcal per gram, more than twice as much as protein or carbohydrate. It supplies the two essential fatty acids your body cannot make (linoleic acid, an omega-6, and alpha-linolenic acid, an omega-3) and it is needed to absorb vitamins A, D, E and K. EFSA puts total fat at 20-35% of energy: on 2,000 kcal, between 44 and 78 g a day.

• Monounsaturated: olive oil, avocado, almonds, olives
• Polyunsaturated: oily fish (salmon, sardines, mackerel), walnuts, flaxseed and seed oils. This includes omega-3 and omega-6 fats
• Saturated: butter, cream, cheese, fatty meat, coconut and palm. EFSA advises limiting it because too much raises blood cholesterol
• Trans: those in partially hydrogenated fats and, in smaller amounts, the natural ones in dairy and meat from ruminants. EFSA advises limiting them for the same reason

Macros per 100 g for 18 common foods

This is what people search for most: the macros of sweet potato, feta cheese, onion, mango or peanut butter. Here they are per 100 g, taken from the USDA database (FoodData Central, SR Legacy), with the record number so you can check them. The calories are the USDA figures, which use food-specific factors, so they can differ by a few kcal from the 4/4/9 sum. For any other food, use the food calorie and macro finder.

How to work out the macros of a plate: an example that adds up

The sum is a simple rule of three for each ingredient: grams you eat ÷ 100 × value per 100 g. For example, 200 g of baked sweet potato: 2 × 20.7 = 41.4 g of carbohydrate. For a bowl of baked sweet potato with chicken, feta, onion and olive oil:

Check with the 4/4/9 factors: 46.1 × 4 = 184 kcal from protein, 47.3 × 4 = 189 from carbohydrate and 21.2 × 9 = 191 from fat; 564 kcal in total, within 2 kcal of the USDA sum. The plate is split almost into thirds: 32.7% of the energy from protein, 33.5% from carbohydrate and 33.8% from fat. Using the European label method, which counts the 7.5 g of fibre in the plate separately at 2 kcal per gram, you would get 549 kcal, 3% less. Neither figure is "the right one": they are two calculation conventions.

How to split your macros for your goal, without dogma

There is no magic split. In POUNDS LOST and in DIETFITS, diets very different in carbohydrate and fat produced the same weight loss, and in the Hall and Guo meta-analysis, with the same calories and the same protein, cutting carbs did not cause more fat loss. So rather than choosing fashionable percentages, it makes sense to work in this order:

• Step 1, calories: start from your daily expenditure (the TDEE calculator estimates it) and subtract or add depending on whether you want to lose or gain weight
• Step 2, protein in grams per kilo: 0.83 g/kg if you do not train and around 1.6 g/kg if you do strength training
• Step 3, fat: between 20% and 35% of calories, the EFSA range
• Step 4, carbohydrate: whatever is left. If you train a lot you will get more; if you eat little, less

Two examples for a 70 kg person who does strength training

With numbers, and checking that the sum adds up:

• Maintenance, 2,000 kcal: 112 g protein (448 kcal, 22%, 1.6 g/kg), 68 g fat (612 kcal, 31%) and 235 g carbohydrate (940 kcal, 47%). Total: 448 + 612 + 940 = 2,000 kcal
• Losing fat, 1,600 kcal: 140 g protein (560 kcal, 35%, 2.0 g/kg, within the Morton interval), 44 g fat (396 kcal, 25%) and 161 g carbohydrate (644 kcal, 40%). Total: 560 + 396 + 644 = 1,600 kcal. Carbohydrate ends up slightly below the EFSA range, which is meant for the general population and not for a deficit phase

If you would rather not do the sums by hand, the macro calculator gives you grams of protein, carbohydrate and fat from your weight, height, age, activity and goal.

How to track macros without getting overwhelmed

The most common mistake is trying to nail all three macros from day one. Start with protein, which is the hardest to reach, and total calories: carbohydrate and fat more or less fall into place once those two are under control. Weigh your food for a few days to calibrate your eye, especially the dense foods (oil, nuts, cheese, peanut butter), where a few extra grams add a lot of calories: 10 g of oil is 88 kcal. If you would rather not log everything by hand, in Renzy you take a photo of your plate and get an estimate of calories and macros that you can correct; for packaged food, there is the barcode scanner.