Nutrition experts often recommend a high-protein diet, and food manufacturers have responded by producing all sorts of high-protein foods, alongside various supplements and snacks. It’s well-known that protein is vital for the formation of hair, nails, muscles, and other tissues. Proteins are also the building blocks for enzymes, hormones, and molecules responsible for transporting nutrients throughout the body.
When we consume food, proteins are broken down into amino acids in the stomach, then absorbed in the small intestine. The liver filters out the amino acids the body needs and disposes of the excess through urea and ammonia. Unlike fats and carbohydrates, excess protein isn’t stored in the body but instead eliminated through the kidneys in urine. Humans grow relatively slowly and have lower protein requirements compared to other animals. Generally, around 10% of daily energy intake should come from protein. On average, protein contributes 15% of energy in the human diet, with meat making up 35% of that, grains 22%, and dairy products 14%.
Animal proteins usually provide all the essential amino acids needed by the body, while proteins in grains tend to be low in lysine—an essential amino acid. This is why it's beneficial to combine grains with legumes, which are rich in lysine. For example, baked beans with toast provide a complete amino acid profile. This explains how vegetarians can still get enough protein.
Protein supports growth when the body’s growth demands are high. However, once growth stops, extra protein doesn’t contribute to further growth. One specific type of protein, a byproduct of cheese production, is often marketed as a muscle-building supplement. While it's inexpensive to produce, it’s sold at a significantly higher price in supplement form. In fact, the European Food Safety Authority (EFSA) rejected a health claim in 2010 stating that this protein enhances muscle mass, strength, or endurance. No high-quality recent studies have shown this protein to be more effective than a regular diet in boosting muscle protein synthesis in older men.
There are several reasons why a high-protein diet (one that provides more than 20% of energy from protein) can be unhealthy. It can lead to increased calcium loss from bones, negatively impact pregnancy outcomes, and be toxic for individuals with kidney or liver disease. It may also be risky for people with diabetes. Long-term observational studies consistently show that people who consume large amounts of meat—especially red meat, sausages, and burgers—are more likely to gain weight, develop type 2 diabetes, and die from heart disease or colorectal cancer.
The so-called "Paleo" diet promotes a romanticized image of prehistoric life and advocates for a high-protein diet composed mainly of meat, fish, eggs, nuts, and some fruits and vegetables. It discourages all processed foods, including grains, legumes, and dairy. However, this diet is based on speculation, not historical records. Evidence from nomadic and ancient hunter-gatherer societies suggests their lives were harsh and short. For example, the average life expectancy in the Arctic was around 28 years.
Agriculture and the development of food processing brought food security, enabled the establishment of human settlements, domestication of animals, and the rise of civilizations. Wheat, in particular, was a foundational crop of the Roman Empire. Recently, gluten-free labels—originally meant for the 1% of the population with celiac disease—have led many to believe they need to avoid wheat and other grains, even when it's unnecessary.
Increasing protein intake does not enhance fat loss. While lean meats and fish can support a healthy diet, the same cannot be said for bacon, sausages, burgers, cheese, and salted nuts. Maintaining an adequate protein intake while reducing total calories is important to prevent loss of lean body mass. This can be easily achieved through normal, everyday foods—like oatmeal with milk for breakfast, a bowl of split pea soup with bread, or chicken breast with a bit of cheese—each of which provides sufficient protein.
The body uses dietary protein to build and repair tissues, especially muscles. It’s also used to create enzymes, hormones, and other chemicals. Unlike vitamins and minerals (which are needed in small amounts), the body requires protein in relatively large quantities. However, unlike fat and carbohydrates, protein cannot be stored for later use, so it’s essential to consume it regularly from good sources.
