Most adults need between 1.2 and 1.6 grams of protein per kilogram of body weight per day to maintain muscle mass. For a 170-pound (77 kg) person, that works out to roughly 92 to 123 grams of protein daily. The exact number depends on your age, activity level, and whether you’re eating in a caloric deficit.
Baseline Needs by Activity Level
The official dietary recommendation for sedentary adults is 0.8 grams per kilogram of body weight per day. That’s the minimum to prevent deficiency, not the amount optimized for holding onto muscle. If you do any regular exercise, your needs are higher.
Here’s how protein needs scale with activity:
- Sedentary or light recreational exercise: 0.8 to 1.0 g/kg per day
- Regular moderate exercise or moderate endurance training: 1.2 to 1.5 g/kg per day
- Strength training: 1.6 to 2.0 g/kg per day
- Ultra-endurance athletes: 1.2 to 2.0 g/kg per day
The International Society of Sports Nutrition recommends 1.4 to 2.0 g/kg per day for exercising individuals, with endurance athletes at the lower end and strength-focused athletes at the upper end. These intakes are considered safe and may actually improve training adaptations. A meta-analysis of adults with overweight or obesity found that intakes above 1.3 g/kg per day were associated with increased muscle mass, while anything below 1.0 g/kg per day raised the risk of muscle loss.
To put this in practical terms: a 150-pound (68 kg) person who lifts weights regularly would aim for about 109 to 136 grams of protein per day. A 200-pound (91 kg) person doing the same would target 145 to 182 grams.
Why You Need More Protein After 50
As you age, your muscles become less responsive to protein. This is called anabolic resistance, and it means the same dose of protein that works for a 25-year-old won’t trigger the same muscle-building signal in someone who’s 60 or 70. Think of it as needing to speak louder for your muscles to hear you.
Research from Stanford Lifestyle Medicine illustrates this clearly. In younger adults (around age 22), 20 grams of protein per meal was enough to stimulate muscle repair. In adults around age 71, muscles were completely unresponsive to 20 grams. They needed 40 grams to get the same effect. For anyone over 50, the recommendation is about 0.4 grams per kilogram of body weight per meal, which translates to roughly 30 to 35 grams per meal for most people.
The ISSN recommends that active older adults aim for 1.4 to 2.0 g/kg per day, the same range as younger athletes. If you’re over 50 and want to hold onto muscle, treating protein like a priority rather than an afterthought makes a measurable difference.
How to Spread Protein Across the Day
Eating your entire daily protein in one sitting isn’t as effective as spreading it across meals. Your body can only use so much protein at once for muscle repair, so front-loading everything at dinner while eating a low-protein breakfast works against you.
Research on older adults found that eating one to two meals per day containing at least 30 grams of protein was associated with significantly greater leg lean mass and muscle strength compared to eating no meals at that threshold. People who hit 30-plus grams in two daily meals had roughly twice the benefit of those who hit it in just one. The association between protein dose and leg lean mass plateaued at about 45 grams per meal for people eating two high-protein meals per day.
A practical target: aim for 30 to 45 grams of protein at two or three meals per day. If you eat three meals, that naturally puts you in the 90 to 135 gram range, which covers the needs of most active adults.
Protecting Muscle During Weight Loss
Losing weight without losing muscle requires eating more protein than usual, not less. When you’re in a caloric deficit, your body is more willing to break down muscle tissue for energy, and higher protein intake is one of the most reliable ways to counteract that.
For people who are dieting without exercising, protein intake of 1.0 to 1.2 g/kg per day (1.25 to 1.5 times the baseline RDA) is recommended. If you’re combining a caloric deficit with resistance training, aim for above 1.2 g/kg per day, and closer to 1.5 times the RDA or higher. Pairing this with regular strength training is essential. Protein alone helps, but the combination of resistance exercise and high protein intake is what reliably preserves lean mass during fat loss.
Does Protein Source Matter?
Animal proteins (meat, fish, eggs, dairy) contain all the essential amino acids your muscles need and are more easily digested. Plant proteins tend to be lower in certain essential amino acids and are generally less digestible, which reduces their muscle-building potential gram for gram.
That said, the practical difference is smaller than you might expect. A systematic review of randomized controlled trials found that animal protein produced a small, statistically significant advantage in percent lean mass (about half a percentage point) compared to plant protein. The difference in absolute lean mass, measured in kilograms, was not statistically significant. Interestingly, this advantage appeared mainly in adults under 50. In older adults, the meta-analysis found no meaningful difference between protein sources.
If you eat mostly plant-based protein, you can close the gap by eating a slightly higher total amount and combining different sources (grains with legumes, for example) to cover the full amino acid spectrum. One specific amino acid, leucine, plays a key role in triggering muscle repair. You need roughly 3 to 4 grams of leucine per meal to maximize that signal, which corresponds to about 25 to 30 grams of high-quality protein. Animal sources like whey, eggs, and chicken are naturally rich in leucine, while plant sources require larger portions to hit the same threshold.
Quick Reference by Body Weight
These ranges assume moderate to regular exercise, the most common scenario for someone trying to maintain muscle:
- 130 lbs (59 kg): 71 to 95 g protein per day
- 150 lbs (68 kg): 82 to 109 g protein per day
- 170 lbs (77 kg): 92 to 123 g protein per day
- 200 lbs (91 kg): 109 to 145 g protein per day
- 220 lbs (100 kg): 120 to 160 g protein per day
If you strength train consistently, move toward the higher end. If you’re over 50, prioritize hitting at least 30 grams per meal and consider the upper end of these ranges. If you’re currently losing weight, add 20 to 30 percent more than you’d normally eat to protect against muscle loss.