Calorie requirements are different for each person and are based on several factors, including activity level, age and gender. Most people are able to maintain their calorie requirements by eating regular healthy meals that include several servings of fruits and vegetables, whole grains and small portions of lean protein, along with healthy fats such as those found in olive oil, avocados and salmon. Seeds, nuts, dairy products and eggs are other nutritious sources of calories.
It is generally accepted that the calorie requirement for the average adult male is around 2,500 a day. Women only need to consume around 2,000 calories a day, though that number can jump to as high as 2,500 if a woman is pregnant. Children need to consume around 1,800 calories a day. These figures are adjusted based on the person's activity level, height and current weight. The more someone weighs, the more calories it takes to maintain that weight; the more active one is, the more calories are required to replace calories lost while active.
Those calorie requirements can usually be maintained by eating three healthy meals each day along with two or three small snacks between meals. The majority of calories in meals should come from vegetables, fruits, whole grains and healthy fats. The balance of calories in the meal should come from fish, poultry, eggs, nuts and legumes. Most experts recommend that only a small portion of calories come from red meat, refined grains such as pasta and white rice, and sugar.
It takes a reduction of 3,500 calories to lose 1 pound (0.45 kilograms) of body weight. How quickly the weight is lost is determined by the timeframe in which the 3,500 calories are eliminated from the diet. If calorie requirements are reduced by 500 each day, the weight would be lost within a week. Calories can be reduced through eating less and by exercising more. The most healthful way to lose weight is to reduce calories and exercise at a healthy level.
Another factor in determining calorie requirements is Body Mass Index (BMI). BMI measures body fat using the figures for a person's weight and height. The higher one's BMI, the more calories it takes to maintain the weight. A lower BMI indicates less fat carried on the body and the calorie requirements to maintain weight are less.
There are many tools available to help determine one’s calorie requirements to maintain or lose weight. Many online sites offer calorie and BMI calculators, and scales can be purchased that also measure body fat percentage. Most gyms and fitness clubs will help members measure body fat percentage and calculate BMI.