How much protein is too much? Experts warn of hidden risks

Protein plays a vital role in keeping the body strong and healthy. It supports muscles, skin, hair, and bones while aiding in repair and energy levels. But experts warn that too much can cause problems—both for personal health and the environment.

For over 35 years, official US dietary guidelines have recommended 0.8 grams of protein per kilogram of body weight for the average healthy adult. This advice has remained unchanged since 1989, appearing in every update from 2005 through to 2025. The amount supports muscle maintenance, wound healing, and general bodily functions.

Most active individuals can safely consume between 0.8 to 1.2 grams per kilogram without issues. However, anything beyond 2 grams per kilogram is considered excessive for the average person. Unused protein is broken down and excreted as nitrogen-rich urea, which can pollute wastewater and harm aquatic ecosystems.

Too much protein can also lead to unpleasant side effects. Symptoms like dehydration, bad breath, headaches, and digestive troubles may appear. Over time, excessive intake might even strain the kidneys.

To stay balanced, nutritionists suggest mixing plant and animal proteins. Lean meats are preferable, while protein supplements should be used cautiously to avoid overconsumption.

Sticking to around 0.8 grams of protein per kilogram of body weight remains the long-standing recommendation. A varied diet with both plant and animal sources helps maintain health while avoiding excess. This approach supports the body's needs without risking unnecessary strain or environmental harm.