What Are Protein?
“When protein is broken down in the body it helps to fuel muscle mass, which helps metabolism,” said Jessica Crandall, a registered dietitian nutritionist, certified diabetes educator and national spokesperson for the Academy of Nutrition and Dietetics. “It also helps the immune system stay strong. It helps you stay full. A lot of research has shown that protein has satiety effects.”
For example, two recent studies showed that satiety, or feeling full after a meal, improved after consuming a high-protein snack. A 2014 study published in the journal Nutrition compared afternoon snacks of high-protein yogurt, high-fat crackers and high-fat chocolate. Among the women who participated in the study, consuming the yogurt led to greater reductions in afternoon hunger versus the chocolate. These women also ate less at dinner compared to the women who snacked on crackers and chocolate.
A similar study published in 2015 in the Journal of Nutrition found that adolescents who consumed high-protein afternoon snacks showed improved appetite, satiety and diet quality. The teens also had improved moods and better cognition.
How much protein?
The Institute of Medicine recommends that 10 to 35 percent of daily calories come from protein. How that equates to grams of protein depends on the caloric needs of the individual. According to the U.S. Department of Agriculture, the amount of protein foods a person should eat depends on age, sex, and level of physical activity. Most Americans eat enough food from this group, but need to make leaner and more varied selections of these foods.
“A safe level of protein ranges from 0.8 grams of protein per kilogram of body weight [2.2 lbs.], up to 2 grams of protein per kilogram for very active athletes,” said Crandall. “But most Americans truly need to be eating about 1 to 1.2 grams of protein per kilogram of body weight.”
Most people need 20 to 30 grams of protein per meal, said Crandall. “For example, that’s 2.5 egg whites at breakfast or 3 to 4 ounces of meat at dinner.” She said that most American women are not getting anywhere close to adequate protein at breakfast. “That could be hindering their muscle mass, their metabolism and their hormone levels.”
Crandall cautioned parents against stressing protein consumption for their children, who typically get sufficient protein easily. “It’s important to focus on fruits and vegetables for kids, but protein supplementation for kids is going overboard,” she said. When considering how to get protein into kids’ diets, parents should focus on whole foods and natural sources.
After water our body is mostly composed of proteins. Indeed, proteins are the main component of cells and are essential to life. Proteins are often called “the building blocks of life”.
Proteins have complex structures: they are made up of many smaller units called amino acids. These are linked together in a chemical bond forming a long chain. Some of these amino acids are called “essential”, meaning they are crucial for life but cannot be produced by the human body and must be gained through one’s diet.
There are many different types of proteins in the body. For example:
- Muscle mass is made of protein
- Collagen which provides strength and structure to tissues (e.g. cartilage)
- Skin, hair and nails which are mainly composed of proteins
- Hemoglobin which transports oxygen around the body
- Most hormones which act as your body’s chemical messengers are also proteins
- Enzymes which regulate all aspects of metabolism; they support important chemical reactions that allow you to digest food, generate energy to contract muscles, and regulate insulin production
- Antibodies which play a role in your immune response