Few nutrients are as important as protein. Not getting enough of it will affect your health and body composition.
However, opinions regarding how much protein you need vary.
Most official nutritional organizations recommend a fairly modest protein intake.
The DRI (Dietary Reference Intake) is 0.36 grams of protein per pound (0.8 grams per kg) of body weight.
This amounts to:
- 56 grams per day for the average sedentary man
- 46 grams per day for the average sedentary woman
This may be enough to prevent deficiency, but the amount you need depends on many factors, including your activity level, age, muscle mass, physique goals, and overall health.
This article examines the optimal amounts of protein and how lifestyle factors like weight loss, muscle building, and activity levels factor in.
What is protein, and why is it important?
Proteins are the main building blocks of your body. They’re used to make muscles, tendons, organs, and skin, as well as enzymes, hormones, neurotransmitters, and various molecules that serve many important functions.
Proteins consist of smaller molecules called amino acids, which link together like beads on a string. These linked amino acids form long protein chains, which then fold into complex shapes.
Your body produces some of these amino acids, but you must obtain others known as essential amino acids via your diet.
Protein is not only about quantity but also quality.
Generally, animal protein provides all essential amino acids in the right ratio for you to make full use of them. This makes sense, as animal tissues are similar to your own tissues.
If you’re eating animal products like meat, fish, eggs, or dairy every day, you’re likely getting enough protein.
However, if you don’t eat animal foods, getting all the protein and essential amino acids your body needs can be more challenging. If you’re following a plant-based diet, you may be interested in this article on the best protein sources for vegans.
Few people need to supplement with protein, but doing so can be useful for athletes and bodybuilders.
Summary: Protein is a structural molecule comprising amino acids, many of which your body can’t produce on its own. Animal foods are usually high in protein, providing all essential amino acids.
Can aid weight loss and prevent weight gain
Protein is important when it comes to losing weight.
As you may know, you need to consume fewer calories than you burn to lose weight.
Evidence suggests that eating protein can increase the number of calories you burn by boosting your metabolic rate (calories out) and reducing your appetite (calories in).
Consuming 25–30% of your total daily calories from protein has been shown to boost metabolism by up to 80–100 calories per day, compared with lower protein diets.
Yet, protein’s most important contribution to weight loss is likely its ability to reduce appetite, leading to a reduction in calorie intake. Protein is better than fat or carbs at keeping you feeling full.
In one study in men with obesity, consuming 25% of calories from protein increased feelings of fullness, as well as reduced late-night snacking desires and obsessive thoughts about food by 50% and 60%, respectively.
In another 12-week study, women who increased their protein intake to 30% of calories ate 441 fewer calories per day and lost 11 pounds (5 kg) by simply adding more protein to their diet.
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Plus, protein does more than aid weight loss — it can likewise prevent weight gain.
In one study, a modest increase in protein from 15% to 18% of calories reduced the amount of fat people regained after weight loss by 50%.
A high protein intake also helps you build and preserve muscle mass, which burns a small number of calories around the clock.
Eating more protein makes it much easier to stick to any weight loss diet — be it high carb, low carb, or something in between.
According to the previously mentioned studies, a protein intake of around 30% of calories may be optimal for weight loss. This amounts to 150 grams per day for someone on a 2,000-calorie diet.
You can calculate it by multiplying your calorie intake by 0.075.
Summary: A protein intake at around 30% of calories seems to be optimal for weight loss. It boosts your metabolic rate and causes a spontaneous reduction in calorie intake.
Can help you gain muscle and strength
Muscles are largely made of protein.
As with most body tissues, muscles are dynamic and constantly being broken down and rebuilt.
To gain muscle, your body must synthesize more muscle protein than it breaks down.
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In other words, there needs to be a net positive protein balance in your body — often called nitrogen balance, as protein is high in nitrogen.
As such, people who want to build muscle often eat more protein, as well as exercise. A higher protein intake can help build muscle and strength.
Meanwhile, those who want to maintain the muscle they’ve built may need to increase their protein intake when losing body fat, as a high protein intake can help prevent the muscle loss that usually occurs when dieting.
When it comes to muscle mass, studies usually don’t look at the percentage of calories coming from protein but rather the daily grams of protein per kilograms or pounds of body weight.
A common recommendation for gaining muscle is 1 gram of protein per pound (2.2 grams per kg) of body weight.
Other scientists have estimated protein needs to be a minimum of 0.7 grams per pound (1.6 grams per kg) of body weight.
Numerous studies have tried to determine the optimal amount of protein for muscle gain, but many have reached varying conclusions.
Some studies show that consuming more than 0.8 grams per pound (1.8 grams per kg) has no benefit, while others indicate that intakes slightly higher than 1 gram of protein per pound (2.2 grams per kg) are best.
Though it’s hard to give exact figures due to conflicting study results, about 0.7–1 gram per pound (1.6–2.2 grams per kg) of body weight seems to be a reasonable estimate.
If you’re carrying a lot of body fat, using either your lean mass or goal weight — instead of your total body weight — is a good idea, as it’s mostly your lean mass that determines the amount of protein you need.
Summary: It’s important to eat enough protein if you want to gain and/or maintain muscle. Most studies suggest that 0.7–1 gram per pound (1.6–2.2 grams per kg) of lean mass is sufficient.
Protein in pregnancy
During pregnancy, the body needs more protein for tissue development and growth. Protein benefits both the mother and baby.
The authors of one study suggest that people consume 0.55–0.69 grams per pound (1.2–1.52 grams per kg) of protein daily during pregnancy.
Elsewhere, experts recommend consuming an extra 0.55 grams per pound (1.1 grams per kg) of protein per day during pregnancy.
The recommended daily allowance for protein during breastfeeding is 0.59 grams per pound (1.3 grams per kg) per day, plus 25 additional grams.
Dietary sources are the ideal way to obtain any nutrient. Good sources include:
- beans, peas, and lentils
- lean meat
- dairy products
- nuts and seeds
Fish and seafood are also good sources. During pregnancy and lactation, choose fish that are low in mercury and high in omega-3 fatty acids, such as salmon, sardines, and anchovies.
However, take care to avoid those that may be high in mercury, such as shark, swordfish, tilefish, and king mackerel.
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Ideally, you should get all your protein from food sources. In some cases, your healthcare provider may recommend supplements. However, there are no guidelines for supplementing with protein during pregnancy.
Other circumstances that can increase protein needs
Regardless of muscle mass and physique goals, those who are physically active need more protein than those who are sedentary.
If your job is physically demanding or you walk a lot, run, swim, or do any sort of exercise, you need to eat more protein.
Endurance athletes also need significant amounts of protein — about 0.5–0.65 grams per pound (1.2–1.4 grams per kg) of body weight.
Older adults have significantly increased protein needs as well — up to 50% higher than the DRI, or about 0.45–0.6 grams per pound (1–1.3 grams per kg) of body weight.
This can help prevent osteoporosis and sarcopenia, both of which are significant problems among older adults.
People recovering from injuries may likewise need more protein.
Summary: People who are physically active, as well as older adults and those recovering from injuries, have significantly increased protein requirements.
Does protein have any negative health effects?
Protein has been unfairly blamed for a number of health problems.
Some people believe that a high protein diet can cause kidney damage and osteoporosis, but science does not support these claims.
Though protein restriction is helpful for people with preexisting kidney problems, there’s no evidence that protein can cause kidney damage in healthy people.
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In fact, a higher protein intake may lower blood pressure and help fight diabetes, which is two of the main risk factors for kidney disease.
Any assumed detrimental effects of protein on kidney function are outweighed by its positive effects on these risk factors.
Some people have claimed that too much protein can lead to osteoporosis, but research shows that it can prevent this condition.
Overall, there’s no evidence that a reasonably high protein intake has any adverse effects on healthy people trying to optimize their health.
Summary: Protein does not have any negative effects on kidney function in healthy people, and studies show that it leads to improved bone health.
How to get enough protein in your diet
The best sources of protein are meats, fish, eggs, and dairy products, as they have all the essential amino acids that your body needs.
Some plants are fairly high in protein as well, such as quinoa, legumes, and nuts.
However, most people generally don’t need to track their protein intake.
If you’re healthy and trying to stay that way, simply eating quality protein sources with most of your meals, along with nutritious plant foods, should bring your intake to an optimal range.
What “grams of protein” really means
This is a very common area of misunderstanding.
In nutrition science, “grams of protein” refers to the number of grams of the macronutrient protein, not the number of grams of a protein-containing food like meat or eggs.
An 8-ounce serving of beef weighs 226 grams but only contains 61 grams of protein. Similarly, a large egg weighs 46 grams but only packs 6 grams of protein.
What about the average person?
If you’re at a healthy weight, don’t lift weights, and don’t exercise much, aiming for 0.36–0.6 grams per pound (0.8–1.3 gram per kg) is a reasonable estimate.
This amounts to:
- 56–91 grams per day for the average male
- 46–75 grams per day for the average female
Still, given that there’s no evidence of harm and significant evidence of benefit, it’s likely better for most people to err on the side of consuming more protein rather than less.