Photo: medicine.missouri.edu
Amid the current craze for protein, it’s easy to assume that you can’t consume too much. However, excessive protein intake can place additional strain on the body.
Protein is widely recognized as a cornerstone of health, essential for muscles, tissues, the immune system, and metabolism. This is why protein powders, high-protein desserts, and protein bars have become commonplace in supermarkets. But a key question remains: how much protein does the body actually need, and what happens when intake exceeds that amount? Gastroenterologist and nutrition medicine expert Professor Yurdagül Zopf, senior physician and head of the Hector Center for Nutrition, Movement, and Sport at Erlangen University Hospital, has studied these questions extensively. Her research focuses on the relationship between diet, gut health, and metabolism, and she notes that protein is an area rife with misconceptions.
How much protein is actually needed
Before discussing excess, it’s important to understand basic requirements. For healthy adults, the recommended daily allowance is 0.8 g of protein per kilogram of body weight. For someone weighing 70 kg, this equals roughly 56 g per day. Moderate physical activity does not significantly change these requirements. After age 65, protein needs rise slightly to around 1 g per kilogram due to anabolic resistance, a condition in which aging muscles respond less efficiently to protein, making higher intake necessary to maintain muscle mass.
Certain medical conditions can substantially increase protein requirements. In oncology, for example, both the quantity and quality of protein are critical.
Is protein really overconsumed?
Despite the common belief that diets must be “boosted” with protein supplements, most people in Europe already consume adequate—and often excessive—protein from everyday foods. Social media amplifies the idea of constantly increasing protein intake, overshadowing a simple truth: a balanced diet of natural foods typically covers all protein needs. Additionally, many processed high-protein products contain sweeteners, flavorings, and low-quality fats, reducing their overall nutritional value.
What happens when protein intake is excessive
When the body receives more protein than it needs, it must break it down. This process produces nitrogen, which the liver converts into urea and is then excreted via the kidneys, potentially overloading the excretory system. Early signs of excessive protein intake can include bloating, constipation, nausea, or abdominal discomfort. Prolonged extreme consumption, sometimes seen in strength athletes, may affect liver function.
Excess protein also impacts the gut. Undigested protein fragments are fermented by gut bacteria, producing compounds like ammonia or sulfur-containing substances that can disrupt the microbiome. High protein intake also increases fluid requirements; inadequate hydration may lead to headaches, fatigue, and reduced concentration.
When protein becomes problematic
No official upper limit for protein intake exists, but 1.6–2 g per kilogram of body weight per day is considered safe for healthy adults. Problems typically arise only at extreme levels, which are rare in ordinary diets. Children are particularly sensitive, as excessive protein early in life may increase the risk of future overweight.
The protein source matters as well. Large amounts of animal protein place more strain on the kidneys due to higher acid and phosphate content, and in the gut, it can promote inflammatory compounds. Plant-based proteins—such as legumes, oats, and nuts—tend to better support gut microbiome health due to their fiber content.
Excess or deficiency: what to watch for
Signs of excessive protein intake are often subtle but include increased thirst, bad breath, mild nausea, and difficulty concentrating. Protein deficiency, on the other hand, develops gradually, causing fatigue, frequent colds, and brittle nails. When protein is insufficient, the body begins breaking down its own tissues, making the problem harder to detect early.
Experts recommend focusing on quality rather than quantity. Natural foods—lean meats, fish, eggs, dairy, legumes, nuts, and oats—provide protein along with essential micronutrients. Protein intake should also be spread evenly throughout the day, avoiding the confusion between trendy protein products and genuinely healthy nutrition.
Protein is indispensable for the body, but it is not a universal solution to all health problems. In most cases, moderation and a balanced approach are not only sufficient but optimal.
