Most adults generally require about 2,000 calories per day, but that amount can vary widely. Each person's caloric requirements differ based on gender, weight, metabolism and activity level. Other factors -- such as muscle mass, pregnancy and illnesses -- can also affect the number of calories required daily.
Definition
French chemist Nicolas Clement first defined the term calorie in 1824. Calories, according to Clement's definition, are energy measurement units that gauge the amount of energy stored in foods. Calories were originally called ''kilocalories,'' but over the years the term was shortened to calories. Each calorie, also known as a kilogram calorie, or kcal, contains the amount of heat required to raise the temperature of 1 kilogram of water by 1 degree Celsius.
Recommendations
The U.S. Department of Agriculture recommends that an average male, 5-feet-10-inches tall weighing 174 pounds, consume 2,900 calories daily to maintain his weight. The recommendation for an average woman, 5-feet-4-inches tall and 138 pounds, is 2,200 calories per day to maintain her weight. Those figures are based on lifestyles with light to moderate activity levels.
According to The Harvard Medical School Family Health Guide, sedentary men and women will keep their weight stable by daily consumption of about 13 calories per pound of body weight. Moderate physical activity increases the requirement to 16 calories a pound, while intense exercisers need about 18 calories a pound. That means a moderately active 125-pound woman requires 2,000 calories per day. A moderately active 175-pound man needs 2,800 calories.
Factors
The caloric requirements of individuals can vary widely and are based on many factors. The level of physical activity performed each day is one of the greatest factors. People who are extremely active, such as athletes in training and professional dancers, need to take in more calories than people who sit at a desk all day. Metabolic rate also affects the number of calories needed per day. Metabolic rate is how a body determines how much fat to burn and how much fat to store. Age, gender and weight are other factors that impact caloric needs.
Weight Loss
To lose one pound, a person must burn 500 calories per day more than he or she consumes over the course of a week. That deficit usually translates to one-half to one pound of weight loss per week. The Calorie Control Council advises that losing weight slowly is the safest and most effective method, and the most likely to result in long-term loss of body fat. MedlinePlus, a service of the U.S. National Library of Medicine and the National Institutes of Health, recommends women should consume no fewer than 1,200 calories per day, and men should consume no fewer than 1,500 per day, unless they are under supervision of a doctor.
References
- Calorie Content of Foods.com: Definition of Calories
- Calorie Control Council: Weight Maintenance Calculator
- Disabled World: How to Count & Calculate Calories
- The Harvard Medical School Family Health Guide: Good nutrition: Should guidelines differ for men and women?
- MedlinePlus: Tips for Losing Weight
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