What Happens to Your Muscles When You Take Protein Powder

Protein powders are everywhere—lining store shelves, packed in gym bags, featured on smoothie shop menus and even stirred into baked goods. But are they truly worth the hype? Many people turn to protein powder for its supposed benefits, and there’s good reason for that. Protein is essential for tissue growth and repair, hormone and enzyme production and immune function. But what often grabs the spotlight is its link to muscle growth.

While it isn’t a magic bullet for building muscle, it can be a helpful tool when used strategically. We spoke with registered dietitians to break down how protein powder supports muscle health—and how to use it effectively.

What Protein Powder Does for Your Muscles

Protein powder offers a convenient way to support your muscle health. These concentrated scoops of protein —made from ingredients like whey, casein, soy, pea, hemp or collagen—can be mixed into smoothies, stirred into oatmeal or blended into batters. Their versatility makes it easy to boost your protein intake in ways that fit your preferences and routine. And post-workout, they’re especially popular among athletes and active individuals aiming to support muscle growth, strength and recovery.

Supports Muscle Growth

Protein powders provide essential amino acids (EAAs), the building blocks your body uses to build muscle. “Consuming protein, whether in powder form or from whole food, increases the concentration of amino acids in our blood, which in turn can lead to an increased rate of muscle protein synthesis (MPS) in the muscles,” says Briana Butler, M.C.N., RD, LD. She explains that over time, this increased MPS speed supports muscle growth and maintenance, particularly when combined with resistance training. 

She shares that whey protein powder is a standout option for muscle growth thanks to EAA content and quick absorption, but casein, soy and pea protein powders are solid choices as well.

Aids in Muscle Recovery

Exercise, especially intense or strength-training workouts, causes tiny muscle tears that need to heal. “Protein powder can help ‘patch’ that up, ultimately making them stronger and more adaptable,” says Christina Chu, M.S., RD, CSSD. Since muscle is primarily made up of protein, replenishing it is key to recovery. Chu recommends powders that contain at least 2.5 grams of leucine, an amino acid that helps trigger MPS. Butler adds that whey and casein are naturally packed with leucine, but many plant-based powders are now fortified with it.

Helps Prevent Muscle Breakdown

Along with helping to repair muscle, protein powder can also help to preserve it. “Consuming adequate protein is essential to prevent your body from using muscle for energy, which helps lower the risk of sarcopenia [age-related muscle loss],” says Butler. She explains that this is especially important during recovery from surgery, as well as during aging, weight loss and while using GLP-1 medications. Protein powders offer a convenient way to help maintain muscle breakdown and meet increased protein needs. 

May Improve Strength and Exercise Performance

Building strength and enhancing exercise performance isn’t just about how hard you work out; it’s also about how well you fuel. “There is significant research to support that protein intake, when paired with resistance training, can improve muscle strength and endurance,” says Butler. Both dairy- and plant-based protein powders have been shown to support these benefits.

How Much Protein Do You Actually Need?

The baseline recommendation for sedentary adults is 0.8 grams of protein per kilogram of body weight. But that’s a minimum—not necessarily optimal for everyone. “If you’re active, trying to build muscle, lose fat or recovering from illness, you may need more,” she says.

For example, for those who are physically active, needs may range from 1.6 to 2.2 g of protein per kilogram of body weight. As a general rule of thumb for athletes and active individuals, Chu recommends 20 to 40 grams of protein per meal and 10 grams per snack. “However, protein needs vary individually based on goals, activity level and weight, so if you want to figure out your specific dose, schedule a consultation with a trusted dietitian,” adds Chu. And while protein powders are convenient, Chu emphasizes that they shouldn’t completely replace whole food sources of protein.

When and How to Take Protein Powder

Refueling right after a workout can help with recovery, but Butler says what matters most is your overall daily protein intake. When it comes to muscle maintenance, she notes that consistently meeting your daily protein target matters more than timing.

Chu adds that while protein always gets the spotlight for muscle health, carbs also play a vital role. Carbohydrates help replenish glycogen—the stored form of carbs your muscles rely on for energy—and may enhance protein absorption. Pairing your protein shake with fruit or whole grains is more effective than protein alone.

Along with when and how you take your protein powder, both dietitians agree that it’s critical to choose powders that are independently tested by organizations such as NSF Certified for Sport, Informed Choice, Informed Sport or USP. These certifications ensure that your protein powder meets specific safety standards. 

In addition, “you’ll want to look for powders that have 25-30 grams of protein per serving, with 2-3 grams of leucine, and a clear breakdown of ingredients instead of proprietary blends. If you have a sensitive gut, allergies or are looking to balance blood sugars, be sure to assess the ingredients and nutrition facts label for added sugars, common allergens, or potentially irritating additives to ensure it fits your dietary needs and preferences,” says Butler.

Our Expert Take

Protein powder can be a practical tool for meeting your protein needs—especially if you’re active, trying to build or preserve muscle or recovering from illness or injury. While it isn’t a replacement for a well-balanced, food-first diet, it does offer a convenient way to support muscle growth, repair, preservation and strength. Just remember to pair it with a source of carbs and choose independently tested products. Most importantly, consult a healthcare provider to determine the optimal amount to meet your needs and ensure that supplementing protein is right for you.