How Much Protein Do You Really Need?

Proteins are chains of amino acids found in every cell in your body. As the 'building blocks of life,' proteins are used for repair, maintenance and new growth of cells, and they make up a major part of your skin, muscles, organs and glands.

Because proteins in your body are constantly broken down, you need to consume protein in your diet that is digested into amino acids and used to replace the protein your body needs to function.

What are "Complete" and "Incomplete" Proteins?

There are nine essential amino acids that you must get via your diet, as your body does not make them on its own. Foods that supply all of the essential amino acids, like meat, milk, eggs and cheese, used to be called 'complete' proteins, while those that do not were called 'incomplete' proteins. Complementary proteins referred to two incomplete proteins that together provided all of the essential amino acids.

These terms are not widely used to describe foods anymore, however, and the old adage that you had to eat complementary proteins at the same meal to count as a complete protein source has been disproven. As long as you consume all of the essential amino acids from a variety of protein-rich foods in the same day, you'll be fine.

Most Americans Eat More Protein Than They Need

Nutrient deficiencies are common in the United States, but protein is not typically among them. According to the U.S. Centers for Disease Control and Prevention (CDC):

"... most adults in the United States get more than enough protein to meet their needs. It's rare for someone who is healthy and eating a varied diet to not get enough protein."

Generally, you only need about 10-35 percent of your daily calories to come from protein. For an adult woman, this amounts to about 46 grams of protein a day, or 56 grams for men. For most people, two to three servings of healthful protein sources are enough to fulfill your daily protein requirements. Examples of protein serving sizes include:

• 1/2 cup of beans
• 3 ounces of meat or fish
• 1 egg
• 2 tablespoons of peanut butter
• 1 ounce of cheese

What Happens if You Eat Too Much Protein?

Since your body can only use a certain amount of protein each day, if you regularly consume more than your body needs, the extra protein calories will be stored as fat, which can lead to weight gain (each gram of protein has four calories). There are other potentially harmful effects as well, including:

• Liver and Brain Damage: Excess protein can cause ammonia to build up in your body. This can cause your liver to become overworked and, if the ammonia accumulates in your bloodstream, it can cause reduced brain and nervous system function known as hepatic encephalopathy.


• Kidney Disease: Excess protein increases your body's nitrogen intake, which puts a strain on your kidneys and may lead to kidney disease.


• Bone Problems: Excess animal protein may increase your body's calcium loss, negatively impacting your bones.


• Health Effects from Unhealthy Protein Sources: If the protein in your diet comes from unhealthy sources, like processed or charred meats, it may increase your risk of cancer, heart disease or other health conditions related to these foods.

If You're Trying to Lose Weight, Doubling Your Protein Intake May Protect Your Muscles

While too much protein isn't recommended, especially if it comes from unhealthy sources, there are some cases when additional protein is beneficial. When you lose weight, for instance, you want to be sure that it's fat you're losing - not muscle. It used to be thought that significant muscle loss was an inevitable part of overall weight loss, but researchers have found that doubling the recommended daily allowance (RDA) of protein actually prevented muscle loss and promoted fat loss among those trying to lose weight by following a healthy diet and exercising.

This is one example where increasing your protein intake may be highly beneficial, but there are others as well.

Seniors, Pregnant Women, Exercisers Need Extra Protein Too

If you're pregnant or breastfeeding, your body will have an increased demand for protein, which is crucial for growth and development. Seniors also may need extra protein to protect against age-related muscle loss. To stave off such muscle loss, experts say you should lift weights at least twice a week once you reach middle age. However, the benefits of weight training will be limited without an adequate intake of protein to manufacture muscle tissue.

Evidence is mounting that seniors, too, need nearly double the typical RDA of protein to avoid accelerating loss of muscle -- especially if they become bedridden from a prolonged illness or injury.

Further, the timing of your protein intake also become increasingly important as you age, with research showing seniors should consume approximately 25-30 grams of protein at each meal (rather than loading all of your protein into one evening meal, for instance).

When you properly combine weight training with higher amounts of protein at each meal, you can boost your body's muscle-building rate by 50 percent.

No matter what your age, it also appears that consuming an easily digestible form of protein, such as whey protein, following resistance exercises will help to stimulate muscle protein synthesis (MPS), which is necessary for muscle growth. Research shows that young individuals who consume whey protein after resistance exercise have greater MPS than those who consume protein from a plant-based source like soy. So if you're a regular exerciser looking to support healthy muscle growth, consuming the proper protein just after a workout may be beneficial.

What are the Healthiest Sources of Protein?

Healthy protein sources include:

• Chicken and turkey (with the skin removed)
• Wild-caught fish
• Bison
• Lean cuts of beef or pork
• Beans (pinto, black, kidney, split peas, lentils, garbanzo beans)
• Nuts and seeds
• Low- or no-fat dairy products
• Eggs

Most people can safely get all of the protein they need just by eating a balanced diet that includes regular amounts of the foods above. As mentioned, however, if you're a pregnant woman, a senior, or someone who is trying to lose weight or performs resistance exercise regularly, additional protein, such as a high-quality protein shake, may be right for you.