From the Guidelines

A high protein diet can have both positive and negative effects on muscle mass and overall health, depending on individual circumstances.

As a general recommendation, a balanced diet that includes 0.8-1.2 grams of protein per kilogram of body weight per day is suggested for healthy adults 1.
For those looking to build or maintain muscle mass, a higher protein intake of 1.2-1.6 grams per kilogram per day may be beneficial 1.
However, it is essential to note that excessive protein consumption can put a strain on kidney function and may not provide additional benefits 1.

In terms of disease prevention, a high protein diet may help with weight management and improve blood sugar control, but it is crucial to choose protein sources wisely, opting for lean proteins like poultry, fish, and plant-based options instead of processed meats 1.
Additionally, individuals with pre-existing kidney disease or other health conditions should consult with their healthcare provider before making significant changes to their protein intake.

It is also important to consider that muscle mass plays a critical role in overall health, and maintaining or building muscle through a combination of proper nutrition and regular exercise can help prevent chronic diseases like osteoporosis, diabetes, and heart disease 1.
As such, a well-balanced diet that includes adequate protein, along with regular physical activity, is recommended for optimal health outcomes.

In general, it is always best to consult with a healthcare provider before making significant changes to your diet or exercise routine, especially if you have any underlying health conditions or concerns 1.
They can provide personalized guidance and help you develop a plan that meets your unique needs and health goals. Some studies suggest that older adults may require more protein to counteract the age-dependent loss of muscle mass, sarcopenia 1. However, the evidence is not conclusive, and more research is needed to determine the optimal protein intake for older adults 1. It is also important to consider the quality of protein and the overall diet, rather than just focusing on the quantity of protein 1. A balanced diet that includes a variety of protein sources, as well as other essential nutrients, is likely to be the most beneficial for overall health and muscle mass maintenance 1.

From the Research

A high protein diet is often associated with muscle hypertrophy and strength, and is also advocated for weight loss and recovery from intense exercise or injuries 2.
Adequate consumption of dietary protein is critical for the maintenance of optimal health during normal growth and aging, and higher-protein diets have been shown to have positive effects on muscle mass 3.
Higher intakes of protein-source foods, such as red meat, poultry, fish, dairy, and soy, nuts, seeds, and legumes, have been associated with higher muscle mass and functional performance in older adults 4.

In individuals with type 2 diabetes mellitus, a high protein diet (1.2-1.5 g/kg/day) has been shown to improve muscle mass, strength, and physical performance, and may be a more appropriate recommendation to combat sarcopenia 5.
A high protein diet has been found to have no harmful effects on measures of blood lipids, liver, and kidney function in healthy resistance-trained men 6.

The current Recommended Dietary Allowance (RDA) for protein is often misrepresented and misinterpreted as a recommended optimal intake, and higher-protein diets may be beneficial for muscle mass and overall health 3.
Increased protein intake necessarily means that overall energy intake must increase or consumption of either carbohydrate or fat must decrease 2.
Care must be taken to ensure that there is sufficient intake of other nutrients to support the training load when consuming a high protein diet 2.