How Many Calories Are in One Gram of Protein?

...

Protein is a macronutrient, as are fats and carbohydrates. The U.S. Food and Drug Administration categorizes macronutrients as components of food that provide energy or calories. Eating more calories than you need for normal body functions and daily activities can lead to weight gain. Knowing the calories in a gram of protein may help keep your weight under control.

Amino Acids

Proteins are made up of 20 amino acids. Eleven can be synthesized in the body and nine are classified as essential amino acids because they cannot be synthesized in the body and must be obtained from food.

Sources of Protein

Protein is derived from animal and plant sources. Animal sources include meat, poultry, eggs, fish and dairy products. These contain the nine essential amino acids and are classified as complete proteins. Plant sources include vegetables, beans, nuts and legumes. They lack the essential amino acids.

Function of Protein

Protein is responsible for cellular maintenance and growth. It is the building block for all body tissue, including internal organs, muscle tissue, ligaments and tendons.

Need for Protein

A study by William M. Rand, Peter L. Pellett and Vernon R. Young, reported in the American Journal of Clinical Nutrition, suggests that healthy adults require between 0.65 g and 0.83 g of protein for every 2.2 lb of body weight. Athletes and people involved in resistance training require between 1.2 g and 2.2 g of protein per 2.2 lb of body weight, as suggested in a study by Jacob Wilson and Gabriel J. Wilson in the Journal of the International Society of Sports Nutrition.

Calories in Protein

Calories indicate and measure the energy available in food. Fat is the most calorie-dense food and carbohydrates are the body's preferred energy source. According to Ucla.edu, protein and carbs each contain 4 calories per gram and fat contains 9 calories per gram.

REFERENCES & RESOURCES
Comments
PARTNER & LICENSEE OF THE LIVESTRONG FOUNDATION

Copyright © 2018 Leaf Group Ltd. Use of this web site constitutes acceptance of the LIVESTRONG.COM Terms of Use, Privacy Policy and Copyright Policy. The material appearing on LIVESTRONG.COM is for educational use only. It should not be used as a substitute for professional medical advice, diagnosis or treatment. LIVESTRONG is a registered trademark of the LIVESTRONG Foundation. The LIVESTRONG Foundation and LIVESTRONG.COM do not endorse any of the products or services that are advertised on the web site. Moreover, we do not select every advertiser or advertisement that appears on the web site-many of the advertisements are served by third party advertising companies.