The Protein Math That Actually Matters When You Work Out

Active people need 1.2 to 1.7 grams of protein per kilogram of body weight daily to support muscle recovery and growth after exercise. This translates to roughly 54 to 77 grams for a 100-pound person, or 109 to 155 grams for someone weighing 200 pounds.

Why Does Protein Matter So Much After Exercise?

When you work out, your muscle proteins literally break down during the process. "If you aren't eating enough protein, you're going to experience things like physical fatigue, weakness, or pain in your joints or muscles because you're not adequately supporting tissue growth," says Sarah Wardlaw, MS, L/ATC, CES, a Mass General Brigham athletic trainer with a master's degree in nutrition and functional medicine.

Beyond muscle repair, inadequate protein can also affect your immune function and hormones. Your body relies on protein to heal injuries and maintain muscle health even when you're less active than usual.

How Much Protein Should You Eat Based on Your Goals?

The Food and Nutrition Board of the Institute of Medicine and the American College of Sports Medicine recommend the 1.2 to 1.7 grams per kilogram formula, but your specific needs depend on your activity level. Moderately active people should aim for the lower end of this range, while certain groups benefit from higher amounts:

• High-Intensity Athletes: Marathon runners and other endurance athletes involved in sports of higher intensity or duration need more protein for recovery
• Older Adults: Those at increased risk of muscle loss should target the higher end of the protein range to maintain muscle mass
• Muscle-Building Athletes: Powerlifters, offensive linemen, and others seeking to significantly increase weight or muscle mass require additional protein for growth

Wardlaw offers an alternative calculation method based on daily calories: aim for 30% protein, 30% fat, and 40% carbohydrates. For someone eating 2,000 calories daily, this means 600 calories from protein, which equals 150 grams since each gram of protein contains 4 calories.

What Should You Eat Right After Your Workout?

Timing matters when it comes to post-exercise protein. Wardlaw recommends consuming at least 15 to 25 grams of protein within 2 hours after exercise to stimulate muscle growth and repair. This is significantly less than many people think they need—studies show that consuming about 20 grams of protein shortly after exercise is enough to support muscle repair, and amounts over 40 grams don't provide additional benefits in that immediate post-workout window.

To meet your daily protein goals, focus on spreading intake throughout the day. "Your first meal of the day—hopefully for everyone that's breakfast—should have at least 30 grams of protein. That's really important, especially if you're trying to maximize muscle growth," Wardlaw explains. She suggests aiming for another 30 grams with each meal, plus protein-rich snacks like protein bars, cottage cheese, or meat sticks.

The best protein sources include animal proteins like chicken, turkey, pork, and red meat, along with dairy products, eggs, fish, nuts, seeds, and even potatoes. For those following plant-based diets, soy products and plant-based protein powders can help bridge the gap. However, people with chronic kidney conditions should consult their doctor about protein limits to protect their kidneys.