How much protein do you need in a calorie deficit?
In a deficit, aim for 1.6–2.2 g of protein per kilogram of bodyweight per day — or 0.7–1 g per pound, and noticeably more than the 0.8 g/kg baseline quoted for general health. An 80 kg (176 lb) person is therefore looking at roughly 130–175 g a day.
The reason the target goes up while calories go down is that protein’s job changes. At maintenance it maintains. In a deficit it decides how much of the weight you lose is fat and how much is muscle.
This piece is about how much and why. Whether you can go further and actually add muscle while losing fat is a separate question with a person-specific answer — see can you build muscle in a calorie deficit?
What you lose is partly your choice
Weight loss is never purely fat. The split between fat and lean tissue is pushed around by three things you control:
| Lever | Effect on the split |
|---|---|
| Protein intake | Largest dietary influence |
| Resistance training | Largest overall influence |
| Deficit size | Steeper deficit, worse split |
This matters beyond appearance. Muscle is metabolically expensive, so losing it lowers your maintenance calories — which shrinks the deficit you are running and makes the weight easier to put back on. Protein and resistance training are how you avoid paying that tax.
Why the target rises with the deficit
The leaner you get and the steeper the deficit, the more the body looks for amino acids somewhere other than your plate. So scale the target to the circumstances:
- Modest deficit, higher body fat — the lower end, around 1.6 g/kg (0.7 g/lb), is plenty.
- Steep deficit, already lean, training hard — push toward 2.2 g/kg (1 g/lb).
- Very aggressive deficit — the protein target goes up exactly as the room for it goes down, which is one of the better arguments for not cutting too hard.
Going above roughly 2.2 g/kg has not been shown to add much for body composition. It is not harmful for healthy kidneys, but it is calories spent where they may be more useful elsewhere.
The second benefit: fullness
Protein is the most satiating of the three macronutrients per calorie, and it also costs the most to digest — roughly 20–30% of its energy is spent on digestion, against about 5–10% for carbohydrate and fat.
Practically, two meals at identical calories do not feel identical. A 400 kcal meal built around chicken, eggs or lentils will hold you for hours longer than 400 kcal of pastry. That is most of why high-protein diets show better adherence in trials — not metabolic magic, just less hunger for the same budget.
Hitting the number
Most people who miss the target miss it at breakfast and in snacks. Some rough anchors, per 100 g (3.5 oz) cooked:
| Food | Protein |
|---|---|
| Chicken breast | ~31 g |
| Greek yoghurt (0%) | ~10 g |
| Lentils | ~9 g |
| Eggs (2 large) | ~13 g |
| Tofu, firm | ~17 g |
On powder: it is food, not a supplement, and that is the whole point of it. A scoop is a convenient 20–25 g of protein for around 110 kcal, which is useful if you are short. It does nothing a chicken breast does not, so choose on price per gram of protein and whether you will actually drink it — the specific brand is the least important variable in this article.
Where the app sits
Caldown counts energy, not macronutrients — the countdown is about the deficit, and protein is about what the deficit costs you. The two decisions are separate, and a tracker that conflated them would be lying about one of them.
General information, not medical advice. Talk to a doctor or registered dietitian before a significant change to how you eat, particularly if you have any kidney condition.