Most people in a calorie deficit should aim for 1.6 to 2.2 grams of protein per kilogram of body weight per day, which works out to roughly 0.7 to 1.0 gram per pound. That’s significantly more than the standard recommendation for someone eating at maintenance calories, and for good reason: when your body is burning more energy than it takes in, adequate protein is what stands between you and muscle loss.
The exact number within that range depends on how lean you already are, how large your deficit is, and whether you’re strength training. Here’s how to find your target and make it work.
Why Protein Needs Rise During a Deficit
When you eat fewer calories than you burn, your body pulls energy from stored fat, but it also breaks down muscle tissue for fuel. Protein counteracts this in two ways. First, the amino acids from dietary protein give your muscles the raw material they need to repair and maintain themselves, reducing how much muscle your body cannibalizes. Research consistently shows that higher protein intake during calorie restriction mitigates lean mass loss, even when overall food intake drops substantially.
Second, protein is the most filling macronutrient. It triggers the release of several gut hormones that signal fullness to your brain while simultaneously lowering ghrelin, the hormone responsible for making you hungry. This hormonal shift makes a calorie deficit considerably easier to sustain day to day. People eating higher-protein diets during weight loss consistently report less hunger and greater satisfaction after meals compared to those eating the same number of calories with less protein.
There’s also a metabolic bonus. Your body uses 15 to 30% of the calories in protein just to digest and process it, compared to 5 to 10% for carbohydrates and 0 to 3% for fat. This “thermic effect” means that, calorie for calorie, protein gives your metabolism a slightly larger boost than the other macronutrients.
Recommended Ranges by Activity Level
For most people trying to lose weight while keeping their muscle, 1.6 to 2.3 grams per kilogram of body weight is the practical range. Where you land depends on your situation:
- General weight loss (light or no exercise): 1.6 to 1.8 g/kg is a solid target. This is enough to preserve muscle and keep hunger manageable without making your diet feel impossibly restrictive.
- Regular strength training: Aim for 1.8 to 2.3 g/kg. Resistance training increases your muscles’ demand for protein, and a deficit amplifies that demand further. UCLA Health notes that someone aiming to lose weight might go up to 2.3 g/kg to preserve muscle during the process.
- Lean athletes on aggressive cuts: If you’re already relatively lean (under 15% body fat for men, under 25% for women) and cutting hard, the evidence points toward 2.3 to 3.1 g/kg of fat-free mass. A systematic review of resistance-trained lean athletes found that the group that best preserved muscle during substantial calorie restriction consumed 2.5 to 2.6 g/kg. The leaner you are and the deeper the deficit, the more protein you need to protect what you’ve built.
For a practical example: a 180-pound (82 kg) person doing regular strength training would aim for roughly 150 to 190 grams of protein per day.
How to Calculate Your Target if You’re Obese
Standard per-kilogram recommendations can overshoot dramatically for someone carrying a lot of extra body fat, because fat tissue doesn’t require protein the way muscle does. If your BMI is 30 or above, calculating protein based on your total body weight could land you at an unrealistically high number.
A more practical approach is to base your calculation on a “normalized” body weight. Clinical weight loss programs for people with obesity often use the weight you’d be at a BMI of about 22 as the reference point, then apply 1.5 g/kg to that number. So a 5’8″ person weighing 260 pounds wouldn’t calculate protein off 260. They’d calculate off roughly 145 pounds (the weight corresponding to a BMI of 22), landing at about 100 grams per day. That’s a more realistic and still effective target.
Alternatively, you can simply aim for 0.7 to 0.8 grams per pound of your goal body weight. It’s a simpler calculation that gets you to a similar place.
Spreading Protein Across Your Meals
Your body can only use so much protein for muscle maintenance at one time, so how you distribute your intake matters. The current evidence suggests aiming for roughly 0.4 g/kg of body weight per meal, spread across at least four eating occasions. For a 180-pound person, that’s about 30 to 35 grams per meal.
Going higher than 0.55 g/kg per meal (around 45 grams for that same person) doesn’t appear to boost muscle maintenance further. Those extra amino acids still get used for energy or other bodily functions, so they aren’t wasted, but you get more muscle-preserving benefit from even distribution than from loading all your protein into one or two meals. If you’re eating three meals a day, adding a protein-rich snack (Greek yogurt, a protein shake, or a handful of jerky) gets you to four protein feedings without much effort.
What Counts Toward Your Total
All protein sources contribute to your daily number, but some are more efficient than others when calories are tight. Lean meats, poultry, fish, eggs, low-fat dairy, and protein powder pack the most protein per calorie. A chicken breast delivers about 30 grams of protein for roughly 165 calories, while the same amount of protein from cheese might cost you 400 or more calories.
Plant-based sources like beans, lentils, tofu, and tempeh work well too, though they come with more carbohydrates or fat attached. You may need to be more intentional about hitting your target if you eat mostly plant-based, but it’s entirely doable with some planning. Combining different plant proteins throughout the day gives you a complete amino acid profile.
Is There a Safe Upper Limit?
For healthy adults with normal kidney function, protein intakes up to 2.2 g/kg (and even somewhat higher for athletes) have not been shown to cause kidney damage. The concern about high protein harming kidneys comes primarily from studies on people who already have reduced kidney function. In that group, every 10-gram increase in daily protein was associated with a measurable decline in kidney filtration over time. But in people with healthy kidneys, that relationship doesn’t hold.
There are a few practical caveats. Very high protein diets, particularly when combined with very low carbohydrate intake, have been linked in case reports to kidney stone formation and, rarely, a dangerous buildup of acid in the blood. People with only one kidney are generally advised to stay below 1.2 g/kg per day. For everyone else, the 1.6 to 2.3 g/kg range sits well within what the evidence supports as both effective and safe.
If you have any existing kidney concerns, getting your kidney function checked before significantly increasing protein intake is a reasonable step. Otherwise, the bigger practical challenge for most people isn’t eating too much protein during a deficit. It’s eating enough.