For most people who are healthy, eating a high-protein diet for up to six months is not dangerous and may aid in weight loss. However, people with kidney or bone disease need to be much more careful of their protein intake. In addition, eating a high-protein diet for extended periods of time may trigger or contribute to several health problems, so moderation is key.
With a greater understanding of how carbohydrates contribute to weight gain and certain disease conditions such as diabetes, many people are switching to diets higher in protein to meet their calorie requirements. Protein is required to build a variety of structures in the body including ones you can see and appreciate, such as muscle tissue, skin, hair and fingernails, and ones you can’t, such as enzymes and connective tissue. However, high-protein diets can be difficult to maintain and don't always support long-term weight loss.
The recommended amount of daily protein that’s needed to maintain body functions ranges from about 40 grams to 70 grams and depends upon your gender, age, body size and activity levels. If you are a serious athlete or someone who exercises regularly, your protein needs increase because muscle building and repair require the amino acids from dietary protein. Resistance training, such as lifting weights, and endurance workouts require the most protein. For example, bodybuilders and endurance athletes typically need to consume between 0.5 and 0.8 gram of protein per pound of body weight each day for strength and performance gains. Thus, a 200-pound athlete may need to consume between 100 grams and 160 grams of protein a day while training if he wants to see significant improvements.
Organ Function Dangers
Eating too much protein over long periods of time may cause kidney damage and reduced function. Your kidneys process digested and metabolized protein, filtering out excess amounts. The more protein you eat that your body doesn’t need, the more work your kidneys do to remove it from circulation. Over time, the workload can stress the kidneys and reduce their function, especially in people with preexisting kidney disease.
High-protein diets may also have negative effects on the colon or large intestine. For example, meat takes a lot longer to digest than fruits, vegetables or grains, so stomach acidity needs to be high and intestinal motility needs to be good or else there’s a risk of the meat rotting and producing toxins. Elderly people commonly experience digestive problems that may make high-protein diets inadvisable.
Other Potential Dangers
High-protein diets increase acidity in body fluids such as blood and saliva. The blood must maintain a very narrow range of pH, or measure of acidity, so when dietary factors increase acidity, the body often responds by liberating minerals from bones and dumping them into the body fluids and tissues to make them more alkaline. As a consequence, the risks of weak bones, osteoporosis, muscle dysfunction and arterial calcifications increase. This is not a short-term consequence of eating lots of protein, but rather a long-term potential complication. Another possible danger of a high-protein diet is dehydration. Your body uses more water to process and utilize protein, so drinking lots of water is a must.
- Exercise Physiology: Energy, Nutrition, and Human Performance; William D. McArdle et al.
- Human Metabolism: Functional Diversity and Integration; J. Ramsey Bronk
- Human Biochemistry; Charles Dreiling
Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.