Proteins from food are essential for health, but requirements vary, depending on a person’s age, activity levels, body weight, and other factors. Most people should aim for a maximum of 2 grams of protein per kilogram of body weight per day.
Consuming more than this could lead to a range of problems involving the digestive system, blood vessels, and kidneys.
The recommended dietary allowance or RDA for protein depends on factors, such as:
- age
- gender
- 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)Trusted Source, the daily RDA for protein is as follows:
| Life stage and gender | RDA in grams (g) per day |
| Infants and children | |
| 0–6 months | 9.1 |
| 6–12 months | 11.0 |
| 1–3 years | 13.0 |
| 4–8 years | 19.0 |
| Males | |
| 9–13 years | 34.0 |
| 14–18 years | 52.0 |
| 19–70 years and older | 56.0 |
| Females | |
| 9–13 years | 34.0 |
| 14–70 years and older | 46.0 |
| Pregnant or breastfeeding women | |
| All ages | 71.0 |
Being physically active can increase the RDA of protein that people should eat. A 2016 studyTrusted Source 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
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
- dehydration
- unexplained exhaustion
- nausea
- irritability
- headache
- diarrhea
There are serious risks associated with chronic protein overconsumption, including:
- cardiovascular disease
- blood vessel disorders
- liver and kidney injuries
- seizures
- death
Doctors have also linked certain conditions to chronic protein overconsumption:
- type 2 diabetes
- cancer
- osteoporosis and osteopenia
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:
- athletes
- 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?
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 studyTrusted Source 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:
- meats
- dairy products
- nuts
- legumes
- seeds
- 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)