How much protein do you need?
There are two very different numbers, and both are useful:
- The minimum for health: 0.8 g per kg of body weight (0.36 g per lb). This is the Recommended Dietary Allowance – enough to prevent deficiency in almost everyone, but not designed for people who exercise or are trying to lose fat (Dietary Guidelines for Americans).
- The amount for body composition: 1.6–2.2 g per kg (0.7–1.0 g per lb). A meta-analysis of 49 studies found that the benefits for muscle level off at about 1.6 g/kg a day, with some people benefiting up to 2.2 g/kg (Morton et al., 2018). The International Society of Sports Nutrition recommends 1.4–2.0 g/kg for most people who exercise (Jäger et al., 2017).
The calculator uses 1.85 g per kg – the middle of that range and the same target the NutriSmart app sets. If your goal is to build muscle, it uses 2.2 g/kg.
Example
For someone who weighs 68 kg (150 lb):
- Minimum for health: 68 × 0.8 = 54 g a day
- Calculator target: 68 × 1.85 = 126 g a day
- Per meal, over 4 meals: about 31 g
Why protein matters when you’re losing weight
- It protects your muscle. In a calorie deficit, the body can break down muscle as well as fat. Enough protein plus some strength training keeps more of it – which also keeps your metabolism higher.
- It keeps you full. Protein is the most filling macronutrient, which makes eating less easier.
- It costs more energy to digest. Your body uses roughly 20–30% of protein’s calories just to process it, compared with a few percent for fat.
How to split protein across the day
Research suggests aiming for about 0.4 g per kg per meal over at least 4 meals to make the most of protein for muscle (Schoenfeld & Aragon, 2018). In practice: build every meal around a protein source, and add a protein-rich snack if you fall short.
| Food | Portion | Protein |
|---|---|---|
| Chicken breast, cooked | 120 g (4 oz) | 37 g |
| Canned tuna, drained | 1 can (140 g) | 32 g |
| Greek yogurt, plain 2% | 200 g (7 oz) | 20 g |
| Cottage cheese | 150 g (2/3 cup) | 17 g |
| Eggs | 2 large | 13 g |
| Tofu, firm | 150 g (5 oz) | 21 g |
| Lentils, cooked | 200 g (1 cup) | 18 g |
Approximate values from USDA FoodData Central.
Keep track without guessing
Most people overestimate how much protein they eat. NutriSmart sets this protein target for you and tracks it automatically from a photo of your meal or a barcode scan – along with your calories, carbs and fat. For your full daily numbers, see the macro calculator and the calorie calculator.
These are estimates for healthy adults aged 18–80, not medical advice. If you have kidney disease or another medical condition, follow your doctor’s guidance on protein.
Frequently asked questions
How much protein do I need per day?
The minimum to stay healthy is 0.8 g per kg of body weight (about 0.36 g per lb). If you exercise, are losing weight or want to build muscle, research supports 1.6–2.2 g per kg (0.7–1.0 g per lb). This calculator uses 1.85 g/kg, or 2.2 g/kg when your goal is building muscle.
How much protein can I absorb in one meal?
Your body absorbs practically all the protein you eat; the question is how much it uses for muscle building at once. Spreading protein over 3–5 meals of about 0.4 g per kg each (roughly 20–40 g) is the most practical way to make use of it.
Is too much protein bad for your kidneys?
For healthy adults, intakes up to about 2 g per kg of body weight have not been shown to harm the kidneys. People with chronic kidney disease are usually told to limit protein, so they should follow their doctor's advice instead of this calculator.
Should I calculate protein from my current or my goal weight?
If you have a lot of weight to lose (a BMI above about 30), using your goal weight gives a more realistic number. Otherwise, your current weight works well.
Do I need protein powder to reach my target?
No. Protein powder is just a convenient food. Chicken, fish, eggs, Greek yogurt, cottage cheese, tofu and lentils can cover the same needs – powder only helps when you struggle to reach your target with meals.