How Much Protein Should You Take In a Day? | Protein Guide

The Recommended Dietary Allowance (RDA) is 0.8 grams of protein per kilogram of body weight per day.

Most people don’t give protein much thought until they start a new workout routine or hear a vague suggestion to “eat more protein.” But the question of what you actually need per day is surprisingly individual.

The number 0.8 grams per kilogram of body weight pops up everywhere, but it’s a baseline for survival, not a target for optimal health. For some people, especially those who lift weights or are past age 50, the real protein per day number looks very different. This guide walks through the math, the exceptions, and the research.

How The Baseline RDA Is Calculated

The standard RDA for adults over 18 is 0.8 grams of protein per kilogram of body weight. That’s roughly 46 grams daily for a 132-pound woman and 56 grams for a 165-pound man, according to the American Heart Association.

These numbers come from studies tracking nitrogen balance — the point where the body is neither gaining nor losing protein. It’s the minimum needed to avoid deficiency, not a recommendation for peak performance or muscle building.

For an average 150-pound adult, the RDA works out to about 55 grams per day. That’s entirely achievable through a single chicken breast and a Greek yogurt.

Why Most People Need More Than The Minimum

The RDA was designed for the general population, not for people who train, recover from illness, or are losing muscle with age. Once you factor in exercise or aging, the number shifts upward significantly.

• Active individuals: Mass General Brigham recommends 1.2 to 1.7 grams per kilogram for people who work out. That puts a 165-pound person at 90 to 130 grams per day.
• Maximum muscle growth: To maximize muscle protein synthesis, the USADA suggests 1.6 to 2.2 grams per kilogram per day. For that same 165-pound person, that’s 120 to 165 grams.
• Older adults (40+): Mayo Clinic notes that protein needs increase after age 40 to 50 to help preserve lean mass. Consuming 30 to 45 grams per meal is linked with greater leg strength in older populations.
• Even distribution matters: A study in the Journal of Nutrition found that spreading moderate protein across meals stimulates 24-hour muscle protein synthesis better than a single large dinner.

The math is straightforward: multiply your weight in kilograms by your activity-adjusted target. A sedentary person stays near 0.8 g/kg; a regular lifter benefits from aiming closer to 1.6 g/kg.

What Research Says About Muscle Protein Synthesis

Muscle protein synthesis responds to protein in a saturable way — meaning there’s a ceiling per meal. A peer-reviewed paper notes that consuming around 0.4 grams per kilogram per meal, across at least four meals, appears optimal for anabolism. For a 150-pound person, that’s about 27 grams of protein per meal.

Stanford Medicine mapped out the math for a typical adult. Their guide shows that a 150-pound adult protein needs baseline of roughly 55 grams, but they also emphasize that protein becomes more important with age and activity. The takeaway: the RDA is a starting point, not a finish line.

A 2024 study in Frontiers in Nutrition suggests that total daily protein intake matters more than whether you eat it before or after your workout. This is newer evidence, so while it’s promising, individual responses vary.

Notice how wide the range gets. The difference between 60 and 165 grams per day isn’t trivial — it’s the difference between maintenance and muscle building.

How To Calculate Your Own Target

Protein needs depend on your current body weight, activity level, age, and health goals. The baseline formula from MD Anderson Cancer Center is simple: weight in kilograms multiplied by 0.8 gives you the RDA number. From there, adjust upward based on the table above.

1. Find your weight in kilograms: Divide your weight in pounds by 2.2. A 180-pound person weighs 81.8 kg.
2. Pick your activity tier: Sedentary = 0.8, moderate activity = 1.2–1.5, strength training = 1.6–2.0, older adult = 1.2–1.5.
3. Do the math: Multiply your weight in kg by your chosen multiplier. For a 180-pound person starting strength training: 81.8 × 1.6 = 131 grams per day.
4. Divide across meals: To maximize synthesis, aim for 30–40 grams per meal over 3–4 meals. That’s roughly a chicken breast (31g) plus a cup of Greek yogurt (20g) per meal.

One catch: the upper end (2.0–2.2 g/kg) is primarily for athletes under heavy training loads, not for desk-job lifters. Going above about 2.0 g/kg offers diminishing returns for most people.

How The Average Person Really Eats

CDC data from 2005–2006 tracked actual consumption patterns. Men averaged 101.9 grams per day; women averaged 70.1 grams. That’s well above the RDA for both groups, meaning most people already get enough to avoid deficiency.

Here’s the nuance, though: those averages include a wide variety of eating patterns. Some people hit 120 grams easily; others may struggle to reach 50 grams, especially if they skip breakfast or follow a low-calorie diet. The National Center for Health Statistics analysis on the much protein should you base page breaks down these intake gaps by demographic group.

If you’re eating two meals a day with only moderate meat portions, you’re likely on the lower end of the spectrum. Adding a protein shake or an extra serving of eggs at breakfast can close that gap quickly.

The Bottom Line

The RDA of 0.8 g/kg is a solid safety net, but most adults benefit from a higher target — roughly 1.2 to 1.6 g/kg if you’re active or over 40. For a 165-pound person, that’s 90 to 120 grams spread across three or four meals. Use your weight and activity level to find your number, then use the food table above to build your plan around it.

If you’re starting a new resistance training routine or managing an age-related muscle loss concern, a registered dietitian can tailor your daily protein target to match your specific body composition goals and your actual meal patterns.