In order to eat a healthy, balanced diet, it is important to know approximately how many calories you should consume a day and where you should get those calories. Our calories come from macronutrients: carbohydrates, protein and fats. Micronutrients are vitamins and minerals and don't have calories. Water is often considered a micronutrient as well. Macronutrients help the body continue to function and perform the activities for daily living.
Calories
The recommended daily intake is from 2,000 to 2,500 calories to maintain current weight. At this calorie intake level, the average person will be able to meet her needs for energy. Typically, men need more calories than women due to differences in size. Calorie intake can vary, depending on health needs and different life stages. For example, an active teenage boy will require more calories than an elderly woman. Despite this, most people will need the same percentage of macronutrients to fulfill daily needs, just in different overall quantities.
Carbohydrates
Carbohydrates should be the primary source of energy in the diet. Carbohydrates, as implied by their name, are made up of carbon, hydrogen and oxygen. One gram of carbohydrates contains 4 calories. Approximately 45 to 65 percent of caloric intake should be from carbohydrates. For the person eating 2,000 calories a day, this amounts to 900 to 1300 calories from carbohydrates. Athletes may need to eat more carbohydrates before a competition to provide the body with more easy-to-use energy.
Protein
Protein is another important macronutrient made up of amino acids. The amino acids contain carbon, hydrogen, oxygen and nitrogen, making them different from carbohydrates and the only macronutrient to contain nitrogen. Proteins aren't a primary source of energy in the body, but they help in tissue growth and repair. Like carbohydrates, proteins provide 4 calories for every 1 gram of protein. Protein intake should be anywhere from 10 to 30 percent of your daily calories, accounting for 200 to 600 calories or 50 to 150 grams of protein.
Fats
Fats are the macronutrient essential for energy while our bodies are at rest. Fats, like carbohydrates, are made up of carbon, hydrogen and oxygen. It is important to have some fats in our diet for fat-soluble vitamins and because the body needs fat for protection. However, fat should come from unsaturated sources such as vegetable and olive oils. Fats contain 9 calories for each gram consumed. Fats should make up no more than 30 percent of your diet, at most 600 calories in a 2,000-calorie daily diet.
Weight Loss
In order to lose weight, you need to eliminate overall calories, not macronutrients, from your diet. Approximately 500 calories a day should be eliminated either through exercise or eating less. According to the American Dietetic Association, the proportions of macronutrients consumed should stay the same. The elimination of carbohydrates, fats or proteins to lose weight is not only unhealthy but also dangerous. The American College of Sports Medicine advises that for the body to function properly, it is important to consume adequate amounts of the macronutrients and no fewer than 1,200 calories a day for women and 1,800 calories a day for men.
References
- "Nutrition: An Applied Approach"; Janice Thompson and Melinda Manore; 2009.
- "ACSM's Certification Review"; Edited by Khalid Bibi, Ph.D., and Michael Niederpruem; 2010.
- American Dietetic Association; Staying Away from Fad Diets
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