What are macros? Protein, carbs and fat explained
Short answer
Macros, short for macronutrients, are protein, carbohydrate and fat. U.S. food labels count about 4 calories per gram of protein or carbohydrate and 9 per gram of fat, so fat packs more than twice the calories per gram. The National Academies' ranges for adults are 10 to 35 percent of calories from protein, 45 to 65 percent from carbohydrate and 20 to 35 percent from fat.
On this page
How many calories does each macro provide?
About 4 calories per gram for protein and carbohydrate, and 9 for fat. Those are the general factors FDA rules allow food makers to use when they calculate the calories on a Nutrition Facts label. Makers may also use factors specific to a food, which is why your own math won't always match a label or database exactly.
Roasted chicken breast shows the gap. USDA FoodData Central lists 100 grams at 31 grams of protein and 3.6 grams of fat. The general factors give about 156 calories, while USDA's entry, calculated with factors specific to chicken, says 165.
| Macro | Calories per gram | Adult range, share of calories | Other reference points |
|---|---|---|---|
| Protein | 4 | 10–35% | RDA of 0.8 g per kg of body weight |
| Carbohydrate | 4 | 45–65% | RDA of 130 g; fiber 25 g for women and 38 g for men aged 19–50 |
| Fat | 9 | 20–35% | Saturated fat no more than 10% of calories |
What does each macro do?
Each one plays a different role, which is why guidelines give a range for all three rather than just a calorie total.
- Protein helps build and keep muscle. A 2017 position stand from the International Society of Sports Nutrition notes that exercise and protein intake both stimulate muscle protein synthesis. Protein also takes the most energy of the three to digest, 20 to 30 percent of its calories, according to a 2004 review.
- Carbohydrate includes sugars and fiber, both listed under total carbohydrate on U.S. labels. The adult RDA is 130 grams a day, and the FDA notes that a diet high in fiber can lower blood glucose and cholesterol levels and reduce calorie intake.
- Fat supplies essential fatty acids, and the National Academies set intake levels for two of them, linoleic acid and alpha-linolenic acid. The 2025–2030 Dietary Guidelines say saturated fat should generally not exceed 10 percent of daily calories.
How do percentages turn into grams?
Multiply your calories by the percentage, then divide by 4 for protein and carbohydrate or 9 for fat. On 2,000 calories a day, the figure FDA labels use as a general guide, the adult ranges work out to:
- Protein: 50 to 175 grams
- Carbohydrate: 225 to 325 grams
- Fat: 44 to 78 grams
The ranges are wide, so many different eating patterns fit inside them.
Do you need to track macros?
For weight change, calories matter more than the split. A 2011 analysis in The Lancet used a model to estimate that swapping large amounts of carbohydrate for fat at the same calories changes energy expenditure by less than about 100 calories a day. The authors concluded that "a calorie is a calorie" is a reasonable first estimate where energy use is concerned.
Protein gets the most specific advice. The 2025–2030 Dietary Guidelines set a protein serving goal of 1.2 to 1.6 grams per kilogram of body weight a day, and the International Society of Sports Nutrition says 1.4 to 2.0 grams is sufficient for most people who exercise.
Common questions
Is alcohol a macro?
It isn't one of the three, but it does have calories. The 2020–2025 Dietary Guidelines list about 150 calories in 12 ounces of regular beer and about 120 in 5 ounces of wine, and note that alcoholic drinks supply calories but few nutrients.
What macro split is best for weight loss?
There isn't a single best split. In trials reviewed for a 2013 U.S. obesity guideline, lower-fat and higher-fat diets produced similar weight loss at 6 to 12 months when both cut calories by 500 to 750 a day.
Why do the numbers on my label not add up?
Rounding and the calculation method both play a part. FDA rules round calories to the nearest 5 or 10, and makers can use food-specific factors, or count soluble fiber at 2 calories per gram instead of 4.
Sources
- 21 CFR 101.9, Nutrition labeling of food. law.cornell.edu
- U.S. Department of Agriculture, FoodData Central. Chicken, broilers or fryers, breast, meat only, cooked, roasted (FDC ID 171477). fdc.nal.usda.gov
- National Academies of Sciences, Engineering, and Medicine. Dietary Reference Intakes for Sodium and Potassium, Appendix J: Dietary Reference Intakes Summary Tables. 2019. nationalacademies.org
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2025–2030. cdn.realfood.gov
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. Journal of the International Society of Sports Nutrition. 2017;14:20. pubmed.ncbi.nlm.nih.gov
- Westerterp KR. Diet induced thermogenesis. Nutrition & Metabolism. 2004;1(1):5. pubmed.ncbi.nlm.nih.gov
- U.S. Food and Drug Administration. How to Understand and Use the Nutrition Facts Label. Content current as of March 5, 2024. fda.gov
- Hall KD, Sacks G, Chandramohan D, et al. Quantification of the effect of energy imbalance on bodyweight. The Lancet. 2011;378(9793):826–837. pubmed.ncbi.nlm.nih.gov
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020–2025. web.archive.org
- Jensen MD, Ryan DH, Apovian CM, et al. 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults. Circulation. 2014;129(25 Suppl 2):S102–S138. pubmed.ncbi.nlm.nih.gov
Estimates, not medical advice. If you're pregnant, have a medical condition or have a history of disordered eating, talk to a clinician before changing how you eat.
Written by the SeeMeEat editorial team under a pen name.