More protein in your breakfast or snacks won’t give you more muscle without more work – a biologist separates the science from the marketing
Do you really need all those protein supplements in your diet? Djavan Rodriguez/Moment via Getty Images Growing up, my brothers were fascinated by the first “Rocky” movie. They were trying to get stronger and excel in sports, so one scene stood out almost as much as Rocky sprinting up the museum steps: Before sunrise, Rocky cracked raw eggs into a glass and drank them.
Protein is one of the three macronutrients (alongside carbohydrates and fats) essential for the body's functioning. While carbohydrates and fats primarily provide energy, protein's main role is to build and repair tissues, including muscles, skin, hormones, and the nervous system. For example, protein is necessary for the skeletal muscles used in movement, the heart muscle, and the muscles that digest food. The article emphasizes that protein is not just 'muscle food' but supports many vital body functions. Proteins are made up of smaller units called amino acids, of which there are 20 types. Nine of these are essential amino acids because the body cannot produce them and must obtain them from food. Animal-based proteins like eggs, dairy, fish, and meat typically contain all essential amino acids, while most plant proteins are low in one or more. Soybeans are an exception, providing a complete set of essential amino acids.
The amount of protein a person needs depends on factors like age, sex, activity level, and health goals. In January 2026, the U.S. government updated the Recommended Dietary Allowance (RDA) for protein from 0.8 grams per kilogram of body weight to 1.2 to 1.6 grams per kilogram. For a 150-pound (68 kg) person, this means increasing protein intake from 54 grams to between 80 to 110 grams daily. The update reflects a shift toward optimizing health rather than just preventing deficiency. However, many healthy U.S. adults already consume enough protein, and overloading can cause issues like kidney damage or digestive problems. Protein can also aid weight loss by increasing feelings of fullness, but this may reduce intake of other nutrients like fiber, vitamins, and minerals from foods like fruits, vegetables, and whole grains.
Animal proteins are generally more digestible than plant proteins, meaning the body absorbs them more efficiently. Cooking also enhances protein digestibility. For instance, scrambled eggs are easier to digest than raw eggs, which were famously consumed by the character Rocky in the 1976 film. Protein powders, a $20 billion industry, are marketed for muscle growth and reducing muscle loss, especially for older adults or those with low appetites. However, protein powders lack the broader nutritional benefits of whole foods like fish, beans, nuts, or yogurt. Protein-fortified packaged foods, such as protein bars or Pop-Tarts, may contain added sugar, salt, or saturated fats, making them closer to candy bars in nutritional value. Medical organizations recommend obtaining protein from a variety of non-packaged sources.
Building muscle is not solely about consuming more protein. Resistance training, a type of exercise that applies force to muscles, is essential for signaling the body to repair and grow muscle. A 2021 clinical trial found that dietary protein combined with heavy resistance training improved muscle size, strength, and function in older adults. The article highlights that eating more protein alone will not build muscle because the molecular pathways for muscle growth require physical stress on the muscles. Resistance training also helps prevent muscle loss during weight loss from medications like GLP-1 drugs, aging, or injury recovery. For example, Rocky's character in the film knew that drinking raw eggs was not enough; he still had to train rigorously to build muscle.
The protein craze is driven by both scientific evidence and marketing. Protein supports muscle maintenance, growth, injury repair, fullness, weight regulation, and healthy aging. However, the marketing of protein-fortified foods often exaggerates their benefits. While protein is important, adding protein to processed foods like cereal, chips, or coffee does not automatically make them healthier. The article notes that food companies capitalize on consumers' growing interest in protein, with products like protein-enhanced Pop-Tarts. The key takeaway is that protein deserves attention, but a balanced diet with nutritious, whole-food protein sources is more beneficial than relying on protein-fortified processed foods.
