How your macros are calculated
Your daily calories
Mifflin-St Jeor and your activity give your maintenance; then −250, −500 or −750 kcal to lose, +300 to gain. Same rules as the daily calorie calculator.
Protein first
1.6 g per kg of body weight, rounded to 5 g: enough to stay full and keep your muscle while you lose fat.
Then fat
25% of your calories by default. Fat carries 9 kcal per gram, so 25% of 1,500 kcal is about 42 g.
Carbs for the rest
Whatever calories remain go to carbohydrates, at 4 kcal per gram.
Which macro split is best for weight loss?
Studies comparing low-carb and low-fat diets find about the same weight loss when calories and protein are matched. The best split is the one you can keep: pick by taste and by what keeps you full.
| Split | Protein | Carbs | Fat | Good for |
|---|---|---|---|---|
| Enough default | 1.6 g/kg | the rest | 25% | Most people, a simple start |
| Balanced | 30% | 40% | 30% | Variety, family meals |
| High protein | 40% | 30% | 30% | Hunger, strength training |
| Low carb | 35% | 20% | 45% | People who prefer fewer starches |
Calories per gram
- Protein: 4 kcal per gram
- Carbohydrates: 4 kcal per gram
- Fat: 9 kcal per gram
- Alcohol: 7 kcal per gram, with no macro of its own
Protein is the macro that matters most when losing weight: get your own range with the protein calculator, and see when you could reach your goal with the weight loss calculator.
Questions about macros
What are macros?
Macronutrients are the three nutrients that carry calories: protein, carbohydrates and fat. Counting macros means tracking the grams of each, on top of calories.
Do I need to count macros to lose weight?
No. Calories decide weight loss. But hitting your protein makes the deficit easier and protects muscle, so it is worth watching protein first.
What is a good macro ratio for weight loss?
A common start is about 30% protein, 40% carbs and 30% fat, or protein at 1.6 g per kg with fat around 25 to 35%. Low carb and low fat work equally well when calories match.
How many carbs should I eat to lose weight?
Whatever fits after protein and fat. On 1,500 kcal with a balanced split, that is about 150 g a day. Going lower is fine if it suits you.
Sources
- Gardner CD, et al. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss (DIETFITS). JAMA, 2018.
- Morton RW, et al. Protein supplementation and resistance training-induced gains in muscle mass and strength. British Journal of Sports Medicine, 2018.
- Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005.
This calculator gives general estimates, not medical advice. If you have diabetes, kidney disease or another condition, ask your doctor or dietitian before changing your diet.