Most people on a low-carb diet need between 1.2 and 1.6 grams of protein per kilogram of body weight daily, which works out to roughly 80 to 130 grams for someone weighing 150 to 180 pounds. The exact amount depends on whether you’re doing a strict ketogenic diet, a more relaxed low-carb approach, your activity level, and whether you’re trying to lose fat or build muscle.
Why Protein Matters More When Carbs Are Low
When you cut carbohydrates, protein becomes your most important macronutrient to get right. Too little and you lose muscle along with fat. Too much on a strict keto diet and you may have trouble staying in ketosis. The sweet spot is narrower than on a standard diet, which is why this question comes up so often.
Higher protein intake during carb restriction does two critical things. First, it protects your lean muscle mass. A study comparing three calorie-matched diets (all at 1,800 calories and 115 grams of protein per day) found that the group eating just 30 grams of carbs lost 16.2 kg over nine weeks, with 95% of that loss coming from fat. The group eating 104 grams of carbs lost less total weight (11.9 kg), and only 75% of it was fat. The combination of low carbs and adequate protein directed the body to burn fat while sparing muscle.
Second, protein keeps you full. Your brain has a mechanism that tracks how much protein you’ve eaten and adjusts hunger signals accordingly. When protein makes up a larger fraction of your calories, you naturally eat less overall without feeling deprived. This is one reason low-carb diets tend to reduce appetite: they’re almost always higher in protein as a percentage of total calories.
Protein Ranges by Diet Type
Not all low-carb diets treat protein the same way. The difference between a ketogenic diet and a general low-carb diet is significant when it comes to protein targets.
On a ketogenic diet, protein is kept moderate, typically 10 to 20% of total daily calories. Harvard’s School of Public Health notes that the classic keto breakdown is 70 to 80% fat, 5 to 10% carbohydrate, and 10 to 20% protein. On a 2,000-calorie keto diet, that translates to roughly 50 to 100 grams of protein per day. The reason for the cap is that your body can convert excess amino acids from protein into glucose through a process called gluconeogenesis, which can interfere with ketone production.
That said, the fear of protein “kicking you out of ketosis” is often overstated. Research on high-protein, carbohydrate-free diets found that while gluconeogenesis did increase, overall glucose production actually dropped. The body used about 33% of the energy in the newly made glucose just to produce it, meaning the process itself burns calories. So moderate overages in protein are unlikely to derail ketosis for most people.
On a general low-carb diet (like Paleo, South Beach, or Atkins beyond the induction phase), protein is typically higher, often 25 to 35% of calories. These diets are described as high in protein but moderate in fat, in contrast to keto’s high-fat approach. That gives you more room, often 120 to 170 grams of protein per day on a 2,000-calorie plan.
How to Calculate Your Personal Target
The most reliable way to figure out your protein needs is to calculate based on body weight in kilograms. Divide your weight in pounds by 2.2 to get kilograms, then multiply by the appropriate factor for your situation:
- Sedentary or lightly active: 1.0 to 1.2 g per kg of body weight
- Regular exercise or moderate activity: 1.2 to 1.4 g per kg
- Strength training or building muscle: 1.4 to 1.7 g per kg
- High-intensity or competitive athletes: up to 2.0 g per kg
For example, a 170-pound person (77 kg) who does regular resistance training would aim for roughly 108 to 131 grams of protein daily. If you carry significant extra body fat, calculating from lean body mass (your weight minus your fat mass) gives a more accurate number. Research has compared different calculation methods and found that using 1.5 grams per kilogram of fat-free mass produces similar targets to using 1.2 grams per kilogram of total body weight in people at a healthy weight.
A practical shortcut if you don’t know your body fat percentage: aim for 1 gram of protein per pound of your goal weight. If you weigh 200 pounds and want to get to 170, eating around 170 grams of protein daily puts you in a reasonable range.
Protein and Muscle Preservation During Weight Loss
Losing weight always carries some risk of losing muscle along with fat, but protein intake is the single biggest dietary lever you have to prevent that. Higher protein intake increases the availability of amino acids in your bloodstream, which directly stimulates muscle protein synthesis, the process your body uses to maintain and rebuild muscle tissue.
Very-low-carb diets appear to be protective against muscle loss compared to higher-carb diets at the same calorie level, but only when protein is adequate. The research consistently shows that the combination works: restricting carbs shifts your body toward burning fat for fuel, while sufficient protein signals your muscles to stay intact. If you’re eating low-carb but skimping on protein, you lose that protective effect.
This matters even more if you’re in a calorie deficit. During active weight loss, your body is looking for energy anywhere it can find it, including your muscles. Keeping protein at 1.2 g per kg or higher gives your body enough raw material to maintain muscle while pulling energy from fat stores instead.
When High Protein Can Be a Problem
For people with healthy kidneys, high-protein diets within the ranges described above are not harmful. The concern about protein damaging kidneys applies specifically to people who already have chronic kidney disease. The National Kidney Foundation recommends that people with CKD who are not on dialysis limit protein intake, because processing protein waste puts additional strain on kidneys that are already compromised. For those on dialysis, the recommendation flips: higher protein is necessary to replace what dialysis removes.
If you have kidney disease or reduced kidney function, a low-protein diet in the range of 0.2 to 0.8 g per kg per day may be appropriate, which is well below what most low-carb diets call for. This is a situation where your specific medical needs override general dietary guidelines.
Making It Work Day to Day
Hitting your protein target on a low-carb diet is easier than on most other diets because the foods that are naturally low in carbs tend to be rich in protein: meat, fish, eggs, and dairy. A typical day might include three eggs at breakfast (18 g protein), a chicken thigh at lunch (26 g), a portion of salmon at dinner (34 g), and a serving of Greek yogurt as a snack (15 g). That alone gets you to roughly 93 grams without much effort.
The challenge usually isn’t finding protein sources but distributing them throughout the day. Your body can only use so much protein for muscle synthesis at one time, so spreading intake across three or four meals is more effective than loading it all into dinner. Aiming for 25 to 40 grams per meal is a reasonable target for most people.
If you’re on a strict keto diet and worried about overdoing protein, track your intake for a week or two to get a feel for where you land. Most people find they naturally settle into a moderate protein range when they’re eating whole foods and filling the rest of their calories with fat. The people who run into trouble are usually those adding protein shakes on top of already protein-rich meals, pushing well past what their body needs.