How much protein is too much?
The recommended dietary allowance or RDA for protein depends on factors, such as:
- pregnancy and breastfeeding
- activity levels
Adults are generally recommended to eat 0.8 g per kilograms (kg) of body weight daily.
Recommended protein intake
According to the Institute for Medicine (IOM), the daily RDA for protein is as follows:
|Life stage and gender||RDA in grams (g) per day|
|Infants and children|
|19–70 years and older||56.0|
|14–70 years and older||46.0|
|Pregnant or breastfeeding women|
Being physically active can increase the RDA of protein that people should eat. A 2016 study recommends eating:
- 1.0 g of protein per kg of body weight with minimal activity levels
- 1.3 g of protein per kg of body weight with moderate activity levels
- 1.6 g of protein per kg of body weight with intense activity levels
Anyone who is pregnant or breastfeeding will need to eat a lot more protein than other people.
Some studies have also found that people may need to increase the protein intake as they age.
A 2016 study concluded that older adults should eat more protein than is currently recommended to promote healthy aging.
The researchers recommended that adults should ideally consume protein in the range of 1.2–1.6 g per kg of body weight daily, to prevent age-related muscle loss or sarcopenia.
The study also concluded that these amounts would also improve appetite control, satiety, and weight management.
Side effects of too much protein
Consuming too much protein on a regular basis can cause intestinal discomfort and indigestion.
People can typically consume 2 g of protein per kg of their body weight daily, long-term, without any significant side effects.
Some people, such as elite athletes, may be able to eat as much as 3.5 g per kg of body weight daily without any side effects.
Most research indicates that eating more than 2 g per kg of body weight daily of protein for a long time can cause health problems.
Symptoms associated with too much protein include:
- intestinal discomfort and indigestion
- unexplained exhaustion
There are serious risks associated with chronic protein overconsumption, including:
- cardiovascular disease
- blood vessel disorders
- liver and kidney injuries
Doctors have also linked certain conditions to chronic protein overconsumption:
Are high protein diets safe?
The IOM recommend people get between 10 and 35 percent of their daily energy intake from protein.
Most people can safely eat between 2 and 3.5 g per kg of body weight daily, especially those who need more protein than others, such as:
- pregnant and breastfeeding women
- people who do physically demanding jobs
Researchers are still unsure whether very high protein diets are safe, especially when someone is also cutting back on their carbohydrate intake.
What is the effect on weight loss?
High-protein diets may reduce hunger cravings and help with weight loss.
It seems higher protein diets may assist with weight loss.
It is likely that high-protein diets promote weight loss because high protein foods tend to promote a feeling of fullness, helping reduce hunger cravings and overeating.
One small study in adolescent overweight or obese girls found evidence that eating breakfast, especially one high in protein, may help control neural signals that regulate food cravings and reward-driven food behaviors.
More research is needed to understand the full relationship between high protein diets and weight loss.
How can you eat high-protein diets healthfully?
A large variety of plant and animal-based foods are high in protein, including:
- dairy products
- unrefined wholegrain cereal and wheat products
Not all protein-rich foods are ideal for people looking to lose weight or maintain a healthy diet.
Examples of protein-rich, low-calorie foods include:
- 3 ounces (oz) skinless chicken breast (less than 26 g protein and 113 calories)
- 1 scoop of whey protein (less than 24–26 g and 130 calories)
- 6 oz greek yogurt (less than 17 g protein and 100 calories)
- 2 large eggs (less than 12 g protein and 144 calories)
- ½ cup tofu (less than 10 g protein and 95 calories)
- 2 tablespoons (tbsp) peanut butter (less than 8 g protein and 190 calories)
- ½ cup beans (less than 8 g protein and 110 calories)
- 1 oz almonds (less than 6 g protein and 165 calories)
- 1 cup cooked oatmeal (less than 6 g protein and 165 calories)
- ½ cup cooked quinoa (less than 4 g protein and 110 calories)
Who should avoid eating too much protein?
Side effects from protein overconsumption may contribute to kidney and liver conditions.
Some people cannot eat as much protein as others because of conditions that interfere with digestion.
Risk factors associated with developing side effects from protein overconsumption include the following:
- kidney and liver conditions
- low carbohydrate intake
- being deficient in nutrients needed for protein metabolites, including glucose, arginine, glutamine, and vitamins B-6, B-12, and folate
High-protein diets are popular, and studies show that high-protein foods may help to:
- increase satiety or the sensation of fullness after meals
- control and reduce appetite and food cravings
- aid in weight loss and fat mass loss
- control neural stimuli related to food and food behaviors
According to national statistics gathered between 2011 and 2014, most American adults of 20 years of age or more only consumed between 15.6 and 16.1 percent of their daily energy intake from protein.
Most people can, therefore, probably increase their protein intake safely, as long as they are not also cutting back on carbohydrates or have liver or kidney conditions.
People should talk with a doctor or nutritionist before starting a very high-protein diet long-term.