How much protein should you consume each day? When should you eat it, and what are the healthiest sources for it?
Whether you’re a fitness enthusiast seeking to build muscle and endurance or striving for a healthier lifestyle, it’s critical to understand your protein requirements. Unfortunately, there is a lot of conflicting advice and confusion over optimal daily intake. Recommended intakes vary depending on who you ask.
Adding to the uncertainty is the fact that not all proteins are equal when it comes to quality and digestibility.
This article will break down the latest research and provide guidance on ideal protein intake, timing, and the best dietary sources to meet your needs. With some basic knowledge, you can cut through the confusion surrounding protein and make informed choices to support your health goals.
What is Protein?
Protein is a fundamental and essential macronutrient often referred to as the body's "building block" because it is involved in the structure, function, and regulation of almost every tissue and cell. Each of the thousands of proteins in your body has its own job.
Protein is made up of chains of 20 different amino acids that link together in different combinations. Nine of these amino acids — called essential amino acids — cannot be produced by your body and must come from the foods you eat.
These include:
- Histidine
- Isoleucine
- Leucine
- Lysine
- Methionine
- Phenylalanine
- Threonine
- Tryptophan
- Valine
Foods that provide all nine essential amino acids are termed complete proteins. Examples of complete protein sources are animal-based foods like meat, poultry, eggs, and dairy. Your body absorbs animal proteins most easily. Certain plant foods like soy, quinoa, and buckwheat also supply all the essential amino acids.
In contrast, incomplete proteins lack one or more of the essential amino acids. Foods like nuts, seeds, beans, and some grains provide some but not all amino acids essential for human protein needs. If you are a vegetarian or vegan, you should consume a variety of incomplete plant proteins over each day that collectively provide all the nine essential amino acids.
At the end of the day, whether you eat complete or incomplete proteins, consuming adequate essential amino acids allows your body to build the varied proteins needed for optimal health and function.
Why You Need Protein
The human body uses proteins for a wide range of functions.
- Tissue growth and maintenance: Proteins provide structural support to tissues and organs and help maintain their health. Collagen, for example, is a protein that helps rebuild and repair tissues that are constantly renewing, such as skin, hair, nails, tendons, and ligaments.
- Enzymes: Many proteins act as enzymes, which are biological catalysts that facilitate chemical reactions in the body. Enzymes are crucial for processes like digestion and metabolism (breaking down food and drink into energy).
- Hormones: Certain proteins serve as hormones, which are chemical messengers that regulate various physiological processes. Insulin, for instance, is a protein hormone that controls blood sugar levels.
- Immune function: Antibodies are specialized proteins that play a key role in the immune system by recognizing and neutralizing foreign invaders such as bacteria and viruses.
- Muscle function: Proteins in muscles, such as actin and myosin, enable muscle contraction and movement. They’re essential for the growth and preservation of muscle mass.
- Transport: Some proteins, like hemoglobin, transport essential molecules like oxygen in the bloodstream.
- Cell signaling: Proteins are involved in transmitting signals within and between cells, regulating processes like cell growth and differentiation.
- DNA regulation: Certain proteins are responsible for regulating the expression of genes by binding to DNA and influencing gene activity.
- Weight maintenance: Protein is thought to have a satiating effect that benefits weight loss.REF#2993 Consuming adequate protein, getting sufficient exercise, and cutting calories may help preserve lean muscle mass and promote fat loss.
Failing to consume adequate amounts of high-quality protein can negatively impact all of these systems and processes. Your dietary preferences and lifestyle choices affect how much you need for optimum health.
How Much Protein Does Your Body Need?
Determining your protein needs can be confusing. Different experts promote different recommendations, and nutrition labels can be misleading about how much usable protein a food item provides. All proteins are not created equal when it comes to digestibility and amino acid composition.
The international Recommended Dietary Allowance (RDA) for foods is based on “the best scientific judgment on nutrient allowances for the maintenance of good health.”REF#2994 The RDA for protein is set at a minimum of 0.8 grams per kilogram of body weight per day for adults, regardless of age. This is considered the minimum to prevent deficiency.
To calculate your specific needs based on the RDA:
- Multiply your weight in pounds by 0.36 to determine your weight in kilograms.
- Multiply your weight in kilograms by 0.8 to calculate your minimum daily protein requirement.
For example, a 150-pound person weighs 54 kilograms (150 x 0.36 = 54). That weight multiplied by 0.8 suggests 43.2 grams of daily protein for health maintenance.
However, the RDA for protein does not account for individual variations like health status, age, and activity level that alter needs. Blanket recommendations don’t work for everyone. Some researchers advocate for higher intakes of one to two grams of protein per kilogram of body weight per day, especially for active individuals, to support muscle growth and preservation.
Protein Needs for Healthy Aging
Newer research suggests protein needs increase with age due to decreased activity, muscle mass loss, hormonal changes, and reduced protein absorption.REF#2995 Adults over 65 may require 1.0 to 1.2 grams of protein per kilogram of body weight, with higher needs up to 2.0g/kg for those dealing with illness or injury recovery.
Observational data shows that older adults who ate 1.1 grams of protein per kilogram of body weight lost 40 percent less lean mass over three years than those consuming 0.8 grams per kilogram, suggesting that the higher amount is indeed beneficial.REF#2996
Because adults experience a 30 percent to 50 percent decrease in muscle mass between the ages of 40 and 80, you may need to start increasing your protein intake as early as 50. Consuming the minimum RDA after 50 may result in health issues.REF#2997
More research is still needed, but evidence supports increasing protein intake beyond the RDA starting in middle age to preserve muscle mass during aging.
Protein Recommendations for Weight Loss on High-Protein Diets
Several clinical trials have shown that high-protein diets (HPDs) promote weight loss and improve cardiovascular risk factors like blood pressure and triglycerides. Subjects in these studies consumed from 1.07 to 1.60 grams of protein per kilogram of body weight per day. Weight loss was seen in both calorie-restricted and normal-calorie HPDs that lasted six to twelve months.REF#2998
Popular high-protein diets like the Paleo, Atkins, or Zone recommend getting up to 30% of total calories from protein. If you are on such a diet, you can calculate your protein needs as follows:
- Determine your total daily calorie needs. Use a Total Daily Energy Expenditure (TDEE) calculator online to estimate your maintenance or weight-loss daily calorie needs based on age, weight, height, and activity level.
- Multiply your total calorie needs by 0.30 to determine how many calories should come from protein.
- Divide this number of calories from protein by 4 (since protein contains 4 calories per gram).
For example, if you are an active 45-year-old, 150-pound woman trying to lose a pound a week on a 1,600-calorie-a-day diet, you’d need to consume roughly 120 grams of protein a day (compared to the RDA of 43.2 grams of protein for a 150-pound adult):
- 1600 x 0.30 = 480 calories from protein
- 480 calories / 4 cal per gram = 120 grams of protein per day
The Ketogenic diet, which is a very low carbohydrate, high-fat, moderate protein diet, suggests a range of 1.2 to 2.0 grams of protein per kilogram of body weight to help maintain muscle mass in absence of carbs.
In clinical studies on HPDs lasting six to twelve months, there was no evidence of adverse effects, such as an impact on kidney or bone health.REF#2998 Multi-year studies are needed to confirm the safety of long-term high-protein consumption.
In general, active individuals, athletes, and older people may benefit from intakes above the minimum RDA. When losing weight, aim for the higher end of the range to help prevent muscle loss. Spread intake throughout the day from high-quality protein sources.
The Best Sources of Protein for Healthy Living
Dietary sources of protein include animal-based foods like meat, eggs, and dairy as well as plant-based foods like soy, beans, nuts, seeds, and grains. The quality of different proteins varies based on the amino acids they provide. Animal proteins tend to contain all the nine essential amino acids, while plant proteins may be missing one or more.
Research indicates, however, that well-planned vegetarian and vegan diets can provide sufficient protein for most adults.REF#2999 Classic vegetarian diets with legumes, nuts, seeds, and soy-based foods, such as tofu and tempeh, supply adequate total protein and essential amino acids.
This data also shows that when vegetarians consume a modestly lower amount of protein than omnivores, they experience no adverse effects. A small fraction of vegans may be at risk if they don’t include enough protein-rich plant foods in their diet. Further research is needed to assess the actual dietary patterns of those reporting very low protein intake and the effects of their diets.
When choosing protein, the best options in terms of quality and digestibility are those that provide a diverse range of nutrients.
Animal-Based Sources
- Lean Meats: Lean cuts of beef, pork, poultry (chicken and turkey), and game meats are excellent sources of high-quality protein. They are typically rich in essential amino acids and are well-digested.
- Fish: Fish such as salmon, tuna, trout, and cod are not only rich in protein but also provide heart-healthy omega-3 fatty acids.
- Shellfish: Shrimp, crab, lobster, and other seafood are low in fat and provide quality protein.
- Eggs: Eggs are a complete protein source, containing all essential amino acids. They are highly digestible and versatile in cooking.
Dairy Products
- Greek Yogurt: Greek yogurt is a protein powerhouse with high protein content and good digestibility. It's also rich in probiotics, which promote gut health.
- Cottage Cheese: Cottage cheese is another dairy option known for its protein content and digestibility.
- Milk: Cow's milk and soy milk are good protein sources. However, common alternatives like almond and oat milk are fairly low in protein. While one cup of soy milk has 8 grams, almond milk has only one. Dairy milk contains whey and casein proteins, which are highly digestible.
Plant-Based Sources
- Legumes: Beans (such as black beans, kidney beans, and chickpeas), lentils, and peas are good sources of quality protein but lack some amino acids. They are rich in fiber and various nutrients.
- Tofu and Tempeh: Tofu and tempeh are soy-based products that provide complete protein. They are often used in vegetarian and vegan diets.
- Quinoa, Hemp, and Buckwheat: These three plant sources of protein are complete proteins. They are also gluten-free and easy to digest.
- Nuts and Seeds: Almonds, peanuts, sunflower seeds, and chia seeds contain protein and healthy fats but are incomplete proteins, meaning they don’t contain all the nine types of amino acids. They are suitable for snacking and adding to meals.
- Seitan: Seitan, also known as wheat gluten, is a high-protein meat substitute popular among vegetarians and vegans.
Animal By-Products
- Whey and Casein Protein: These proteins are found in dairy products and are highly digestible. They are often used in protein supplements.
- Collagen: Collagen protein is found in animal connective tissues and is known for its benefits for skin, joints, and hair.
Combination Foods
- Whole Grains + Legumes: Combining grains like rice or whole wheat bread with legumes (e.g., beans or lentils) can create a complete protein source with a good amino acid profile.
In general, animal proteins rank highest in bioavailability. Combining certain plant proteins can also provide all the essential amino acids you need.
The key to a healthy diet is to stick with whole foods as much as possible. Despite marketing claims that heavily processed vegetarian meat substitutes provide ample protein, they may not, so it is best to avoid them. Additionally, heavily processed foods in general are not good for your health.
How to Determine the Protein Count in Foods
There are multiple scientific calculations for measuring the protein content in food, which is why you’ll find different values for the same serving size of a specific food item from different sources. For instance, search the Internet for protein in a six-ounce chicken breast. You may find results that range from 38 grams to 54 grams. Because of this, your total protein count will be an estimate, especially when it comes to fresh food.
For whole foods, look up the protein content online or in nutrition databases. You can find apps that specifically calculate protein content. Also, invest in a food scale (many options are available for under $15) and weigh or measure your servings to ensure the most accurate protein count.
You can find the protein count of packaged foods on the product’s nutrition label. Look for the serving size and grams of protein per serving. Good sources provide at least five to ten grams per serving. Compare brands and choose options higher in protein.
A Sample Daily Menu Following the RDA for Protein
While your meal choices will depend on your food preferences, it’s important to make sure you add protein to every meal. Consider the following daily menu for an idea of how to incorporate protein into your diet. This menu exceeds the minimum RDA of 43+ grams for a 150-pound adult, demonstrating how easy it is to get enough protein when you plan your meals.
Food Protein Count
Oatmeal (1/2 cup dry) 6 grams
½ cup blueberries .5 gram
½ cup cow’s milk 4 grams
Lunch
2 cups shredded romaine lettuce 1.2 grams
¼ cup kidney beans 10 grams
1 medium tomato 1 gram
¼ avocado 1 gram
½ cucumber <.5 gram
Olive oil and vinegar 0 grams
Dinner
4 ounces roasted chicken breast 35 grams
1 cup green beans 1.8 grams
1/2 cup brown rice 2.5 grams
When putting together your meal plan, make sure you balance it with healthy carbohydrates and fats. This menu is easily converted to vegetarian or vegan by substituting a plant-based milk for cow’s milk and fried or roasted tofu for the chicken breast.
Once you understand your requirements and have a list of the foods you need to meet them, you’re on your way to a healthy diet for life.