GUIDES
Macros explained
Protein, carbohydrates and fat in plain language: what each does, how much you need, and how to set your split
| Nutrient | Calories per gram | Main job |
|---|---|---|
| Protein | 4 | Builds and repairs muscle and tissue; the most filling |
| Carbohydrate | 4 | The body’s quickest fuel; includes fiber |
| Fat | 9 | Stores energy, carries vitamins A, D, E and K |
| Alcohol | 7 | No nutritional need |
Protein
Protein is made of amino acids, the building blocks of muscle, skin, enzymes and hormones. Adults need at least 0.8 g per kilo of body weight a day. While losing weight, 1.2 to 1.6 g helps you stay full and keep muscle, according to a review by Leidy and colleagues in the American Journal of Clinical Nutrition 1. In a controlled feeding study, raising protein from 15% to 30% of calories made people eat about 440 fewer calories a day without trying 5. If you strength train, extra protein adds to your gains, with little further benefit above about 1.6 g per kilo a day 6.
Carbohydrates: sugar, starch and fiber
Carbohydrates come in three main forms. Sugars are found naturally in fruit and milk and are added to many foods. Starches are in bread, rice, pasta, potatoes and legumes. Fiber is the part of plants we can’t fully digest, which feeds gut bacteria, slows digestion and keeps you full.
The World Health Organization recommends keeping free sugars, those added to foods plus those in honey, syrups and juices, under 10% of your calories, and ideally under 5%, about 25 g or 6 teaspoons a day 3. Fiber is the opposite story: a series of reviews in The Lancet in 2019 found that people eating 25 to 29 g of fiber a day had 15 to 30% lower risk of dying early, heart disease, stroke, type 2 diabetes and colorectal cancer than those eating the least, and whole grains showed similar benefits 2. Most people eat far less fiber than that.
| Food | Portion | Fiber |
|---|---|---|
| Lentils | 1 cup cooked | About 15 g |
| Chia seeds | 2 tablespoons | About 10 g |
| Raspberries | 1 cup | About 8 g |
| Oats | 1 cup cooked | About 4 g |
| Apple | 1 medium, with skin | About 4 g |
| Whole-grain bread | 1 slice | About 2 to 3 g |
| Broccoli | 1 cup cooked | About 5 g |
Fat: the good, the moderate and the avoidable
Fat is essential: it builds cell walls, makes hormones and carries vitamins A, D, E and K. But at 9 calories per gram, it adds up fast. Its type matters for your heart. Unsaturated fats, from olive oil, nuts, seeds, avocado and oily fish, are linked to better heart health, as in the PREDIMED trial 7. A Cochrane review of 15 trials found that cutting saturated fat, from fatty meat, butter and cheese, lowered combined cardiovascular events by about 17%, especially when it was replaced with unsaturated fats 4. Industrial trans fats, from partially hydrogenated oils, are best avoided altogether.
Setting your macros
Five steps
- Find your calorie target with the calculator.
- Set protein first: 1.2 to 1.6 g per kilo of body weight.
- Give fat about 25 to 35% of your calories, mostly unsaturated.
- Fill the rest with carbohydrates, mostly from whole grains, fruit, vegetables and legumes.
- Aim for 25 g of fiber a day or more, and keep free sugars low.
| Split | Protein | Fat | Carbohydrate |
|---|---|---|---|
| Balanced (25 / 30 / 45%) | About 112 g | 60 g | About 203 g |
| Lower-carb (30 / 45 / 25%) | 135 g | 90 g | About 113 g |
Does the split matter for weight?
Not much, when calories are the same. In POUNDS LOST, a two-year trial of four diets with different amounts of fat, protein and carbohydrate, weight loss was similar on all of them 8, and in DIETFITS healthy low-fat and low-carb diets led to similar results over a year 9. In a metabolic ward, switching to a very low-carb diet didn’t speed up fat loss at all 10. Choose a split you enjoy and can keep, with enough protein and fiber.
Myths and facts
Myth Carbs make you fat.
Fact Excess calories do, from any source. Diets with very different amounts of carbohydrate lead to similar weight loss 8, and fiber-rich carbohydrates are linked to better health 2.
Myth Fat makes you fat.
Fact Low-fat diets don’t beat others for weight loss 9,11, and unsaturated fats are good for the heart 7.
Myth The more protein, the better.
Fact Benefits level off around 1.6 g per kilo a day 6. Beyond that, extra protein mostly adds calories and cost.
Questions
Do I need to count macros?
No. Counting calories, or just following a diet, works for weight loss. Tracking protein can help if you often feel hungry or want to keep muscle.
How much fiber should I eat?
At least 25 g a day; more is better for most people 2. Increase it gradually over a few weeks and drink plenty of water to avoid bloating.
Is fruit sugar bad for me?
Sugar in whole fruit doesn’t count as free sugar: it comes with fiber and water. Fruit juice and smoothies do count 3.
Sources
- Leidy HJ, Clifton PM, Astrup A, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(6):1320S-1329S. doi.org/10.3945/ajcn.114.084038
- Reynolds A, Mann J, Cummings J, et al. Carbohydrate quality and human health: a series of systematic reviews and meta-analyses. Lancet. 2019;393(10170):434-445. doi.org/10.1016/S0140-6736(18)31809-9
- World Health Organization. Guideline: Sugars intake for adults and children. Geneva: World Health Organization; 2015. www.who.int/publications/i/item/9789241549028
- Hooper L, Martin N, Jimoh OF, et al. Reduction in saturated fat intake for cardiovascular disease. Cochrane Database Syst Rev. 2020;8(8):CD011737. doi.org/10.1002/14651858.CD011737.pub3
- Weigle DS, Breen PA, Matthys CC, et al. A high-protein diet induces sustained reductions in appetite, ad libitum caloric intake, and body weight despite compensatory changes in diurnal plasma leptin and ghrelin concentrations. Am J Clin Nutr. 2005;82(1):41-48. doi.org/10.1093/ajcn/82.1.41
- Morton RW, Murphy KT, McKellar SR, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults. Br J Sports Med. 2018;52(6):376-384. doi.org/10.1136/bjsports-2017-097608
- Estruch R, Ros E, Salas-Salvadó J, et al. Primary Prevention of Cardiovascular Disease with a Mediterranean Diet Supplemented with Extra-Virgin Olive Oil or Nuts. N Engl J Med. 2018;378(25):e34. doi.org/10.1056/NEJMoa1800389
- Sacks FM, Bray GA, Carey VJ, et al. Comparison of Weight-Loss Diets with Different Compositions of Fat, Protein, and Carbohydrates. N Engl J Med. 2009;360(9):859-873. doi.org/10.1056/NEJMoa0804748
- Gardner CD, Trepanowski JF, Del Gobbo LC, et al. Effect of Low-Fat vs Low-Carbohydrate Diet on 12-Month Weight Loss in Overweight Adults and the Association With Genotype Pattern or Insulin Secretion: The DIETFITS Randomized Clinical Trial. JAMA. 2018;319(7):667-679. doi.org/10.1001/jama.2018.0245
- Hall KD, Chen KY, Guo J, et al. Energy expenditure and body composition changes after an isocaloric ketogenic diet in overweight and obese men. Am J Clin Nutr. 2016;104(2):324-333. doi.org/10.3945/ajcn.116.133561
- Shai I, Schwarzfuchs D, Henkin Y, et al. Weight Loss with a Low-Carbohydrate, Mediterranean, or Low-Fat Diet. N Engl J Med. 2008;359(3):229-241. doi.org/10.1056/NEJMoa0708681
MAKE IT A HABIT
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dieting.app is general information, not medical advice. If you are pregnant or breastfeeding, have diabetes, kidney disease or a history of eating disorders, or take medication, talk to your doctor before changing how you eat.