Protein Calculator for Weight Loss
How much protein to eat while losing fat and keeping muscle. 2.3 to 3.1 g per kg of fat-free mass, the range of a 2014 review on protein during calorie restriction.
Your protein per day
146 to 197 g/day
2.3 to 3.1 g per kg of fat-free mass- Fat-free mass 140 lb
- Same range on total weight 209 to 281 g
- Over 4 meals 37 to 49 g each
Worked example
A person who weighs 200 lb (90.7 kg) with about 30% body fat, lifting weights during a diet:
- Fat-free mass = 90.7 × (1 − 0.3) = 63.5 kg (140 lb)
- Protein = 63.5 × 2.3 to 3.1 = 146 to 197 g a day
- Over 4 meals = 37 to 49 g each
Protein for weight loss by body fat
For the weight entered in the calculator above; the row closest to your body fat is highlighted.
| Body fat | Fat-free mass | g/day |
|---|---|---|
| 20% | 160 | 167 to 225 |
| 25% | 150 | 156 to 211 |
| 30% | 140 | 146 to 197 |
| 35% | 130 | 136 to 183 |
| 40% | 120 | 125 to 169 |
Fat-free mass is shown in the unit selected above (lb or kg).
What changes versus the general protein calculator
- Per kg of fat-free mass, not total weight. The general protein calculator applies 2.3 to 3.1 g/kg to total body weight for its fat loss goal; this page follows the 2014 review and applies it to fat-free mass, which lowers the target when body fat is higher.
- A body fat input, with a table from 20 to 40% for when you only have a rough idea.
- Defaults: 200 lb at 30% body fat instead of 180 lb.
Frequently asked questions
How much protein should I eat to lose weight?
If you lift weights while eating in a calorie deficit, a 2014 systematic review suggests 2.3 to 3.1 g per kg of fat-free mass a day. At 200 lb and 30% body fat, that is 146 to 197 g a day.
Why does this calculator use fat-free mass?
The 2014 review gives its range per kg of fat-free mass (everything except fat). With more body fat, the same g/kg applied to total weight gives a much higher number: 209 to 281 g a day for the default profile, against 146 to 197 g on fat-free mass.
Do I need more protein the leaner I get?
The 2014 review says protein needs scale upward with the size of the calorie deficit and with leanness. Leaner people in a steep deficit sit toward 3.1 g/kg of fat-free mass, others toward 2.3.
What if I do not lift weights?
The 2014 review looked at resistance-trained, lean athletes. If you do not train, the general protein calculator gives Health Canada's minimum of 0.8 g/kg and the 1.4 to 2.0 g/kg range for regular exercise.
Weekly plan based on your numbers
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Medical disclaimer
This calculator gives an estimate, not medical advice. Equations predict the average of a group; your own needs can sit 10% or more above or below. It is built for healthy adults. If you are pregnant or breastfeeding, under 18, living with a medical condition such as diabetes, kidney disease or an eating disorder, or taking medication that affects appetite or weight, ask your doctor or a registered dietitian before acting on these numbers.
Sources
- Helms ER, Zinn C, Rowlands DS, Brown SR. A systematic review of dietary protein during caloric restriction in resistance trained lean athletes: a case for higher intakes. Int J Sport Nutr Exerc Metab. 2014;24(2):127-138. DOI: 10.1123/ijsnem.2013-0054 (read 2026-10-24)
- Jäger R, Kerksick CM, Campbell BI, et al. International Society of Sports Nutrition Position Stand: protein and exercise. J Int Soc Sports Nutr. 2017;14:20. DOI: 10.1186/s12970-017-0177-8 (read 2026-10-24)
- Health Canada. Dietary Reference Intakes tables: reference values for macronutrients (2005). (read 2026-10-24)