Although protein is an essential nutrient your body needs daily to function properly, getting too much protein can lead to unpleasant -- and dangerous -- side effects. Nutrient deficiencies may occur if you're eating protein in place of other essential nutrients. Aim to consume protein in recommended amounts to optimize your health.
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Recommended Daily Intake
Keep your protein consumption to approximately 35 percent of your daily calorie needs, recommends the Institute of Medicine. Protein provides 4 calories per gram. Therefore, individuals consuming 2,500 calories daily should aim for about 219 grams of protein, those who consume 2,000 calories a day should avoid eating more than 175 grams of protein and individuals following 1,600-calorie diets should consume about 140 grams of protein daily.
A 2006 review published in the "International Journal of Sport Nutrition and Exercise Metabolism" reports that excess protein intake can cause nausea and diarrhea. If you couple a high protein intake with a low-carb diet, you may also experience fatigue, headaches and weakness. A study published in 2010 in "Annals of Internal Medicine" notes that participants who followed a high-protein, low-carb weight-loss diet reported bad breath, hair loss, dry mouth and constipation.
Getting too much protein, especially long-term, can even lead to dangerous side effects and may cause health problems. The 2006 review in the "International Journal of Sport Nutrition and Exercise Metabolism" reports that excess protein can exceed your liver's ability to properly break down and excrete the protein, which can lead to toxin buildup in your blood or even death. A study published in 2012 in the "American Journal of Kidney Disease" found that following a high-protein diet over the long term may lead to kidney disease.
Minimum Protein Needs
While eating too much protein can be harmful, not getting enough protein is also problematic. Protein malnutrition can lead to decreased muscle mass, hair and skin changes, irritability, a weakened immune system and even swelling or shock, according to MedlinePlus. The Institute of Medicine suggests men eat at least 56 grams of protein daily, women consume 46 grams and pregnant and nursing women obtain at least 71 grams of protein daily. Protein-rich choices include eggs, lean meats, poultry, seafood, low-fat dairy foods, soy products, seitan, nuts, seeds and legumes.
Protein provides the necessary materials for the body to build and repair tissue, and produce hormones, among other vital functions. Most Americans get more than adequate amounts of protein in their diet, making deficiencies rare. Adult women should get 46 grams per day, adult men 56 g. You might think that if protein is so important, wouldn't more be better? Unfortunately, that is not the case. Excess protein consumption can have unexpected consequences.
The human body relies primarily on fat and carbohydrates for energy. With excessive protein intake, your diet might fall short of the recommended dietary consumption of these energy sources. Your body can break down proteins for fuel if needed, but it requires more energy and resources to do so, making it less efficient. A low-carb diet might impact your endurance so you cannot exercise as long.
The human body tends to respond conservatively to excess food intake by storing the excess so it has resources to turn to in times of stress. Excessive protein intake is no exception. However, extra protein is stored as fat that can lead to weight gain. Some people might follow a high-protein diet thinking that it might help them lose weight. In reality, this strategy might backfire if you do not keep total calorie intake in line with energy expenditure. Being overweight carries several serious health consequences, including an increased risk of heart disease and diabetes.
Digestion is a complicated process. Excess protein intake can impact it negatively, leading to lower bone density. A 2010 study by the Chinese Center for Disease Control and Prevention found that excessive protein intake, particularly from animal sources, decreased bone mass buildup in individuals with low calcium intake. Most disturbing about these findings is that the participants in the study were pubescent adolescents. Low bone mass density at this age sets the scenario for an increased risk of osteoporosis later in life. Even with adequate calcium intake, excess protein can increase calcium excretion, further complicating this risk.
Metabolic Rate Changes
A diet change to include higher protein intake can also affect your metabolic rate. The reason behind this phenomenon lies in the chemistry behind protein metabolism. The process requires more water, which can, in turn, lead to dehydration. Protein breakdown also increases the demand for oxygen. When you exercise vigorously, your body turns to carbs for energy because it is more efficient. The process requires oxygen. Excess protein consumption can deprive the body of the oxygen it needs to fuel activity, further impacting your athletic performance.
- International Journal of Sport Nutrition and Exercise Metabolism: A Review of Issues of Dietary Protein Intake in Humans
- Annals of Internal Medicine: Weight and Metabolic Outcomes After 2 Years on a Low-Carbohydrate Versus Low-Fat Diet
- American Journal of Kidney Disease: Effect of a High-Protein Diet on Kidney Function in Healthy Adults: Results From the OmniHeart Trial
- MedlinePlus: Kwashiorkor