Carbohydrates, proteins, and fats are the nutrients that provide the body with energy, measured in calories. There are 4 calories in a gram of carbohydrate or protein and 9 calories in a gram of fat. Carbohydrates supply energy the quickest, and fats the slowest. Carbohydrates are broken down in the intestine into sugars, proteins into amino acids, and fats into fatty acids and glycerol.
Carbohydrates
Carbohydrates are the major energy source in human nutrition. Carbohydrates are a primary fuel source for some cells and a readily available fuel for all cells in the form of blood glucose. Muscle cells also rely on a dependable supply of carbohydrates to fuel intense physical activity. Carbohydrates are stored in the human body as glycogen mainly in the liver and muscles.
Carbohydrates stored in the liver can be used to maintain blood glucose availability in times when the diet does not supply enough. However, regular intake of carbohydrate is important, because liver glycogen stores are exhausted in about 18 hours if no carbohydrate is consumed. Some of the carbohydrates consumed in excess of the body’s needs at the time are stored in cells as glycogen and the rest are converted to fat.
It’s generally recommend that approximately 50% of total daily calories should consist of carbohydrates.
Proteins
Proteins are the main building blocks of the body, consisting of amino acids that the body relies on from food. Proteins are complex molecules that take longer to be broken down in the body resulting in a slower and longer-lasting source of energy than carbohydrates.
Proteins are essential for the body to maintain and replace tissues and other metabolic processes, but only when there is sufficient carbohydrate and fat intake can food proteins be utilized most efficiently. When more protein is consumed than required, it gets broken down by the body and stored as fat. It’s generally recommend that approximately 20% of total daily calories consist of protein with bodybuilders and children needing more.
Fats
Fats are complex molecules composed of fatty acids and glycerol. Fats are needed for growth and energy. Fats are the slowest and most efficient source of energy and any excess energy gets stored as fat in the abdomen and under the skin. Excess fat also gets stored in blood vessels and within organs, where it can cause inflammation and lead to disease. It’s generally recommended that fat be limited to no more than 30% of daily total calories.
Carbohydrate, Protein and Fat Ratio Calculators
There are several useful carbohydrate, protein and fat ratio calculators on the web. Two of the best that we have found are:
Freedieting’s Calorie Calculator which can be found here that allows you to adjust your carb, protein and at ratios at will.
Scientific Psychic’s Diet Calculator that can be found here.
References:
1. The Merck Manual – Home Health Handbook.
2. Hugo Rivera – Bodybuilding Guide
3. J. J. Strain, Benjamin Caballero. Encyclopedia of Human Nutrition
4. Katz, David L.; Friedman, Rachel S.C. Nutrition in Clinical Practice: A Comprehensive, Evidence-Based Manual for the Practitioner
Thanks for the calculators! Unless you are bodybuilding (which would require more carbs and protein with less fats) then I would agree with the ratio of 50% carbs, 20% protein and 30% fats. Although I do feel that fats are a tad high – as long as people are ingesting the ‘good’ fats such as those that come from avocados then everything should be fine.
Once again, great article – the information should benefit anyone who is trying to lead a better lifestyle and fix their diets.
Take Care
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Lovely site! Enjoyed reading the content of nutritional categories highlighted!