How Many Calories Should I Eat ?

The number of calories people should eat each day depends on several factors, including their age, size, height, sex, lifestyle, and overall general health. A physically active 6ft 2in male, aged 22 years, requires considerably more calories than a 5ft 2ins sedentary woman in her 70s.

Recommended daily calorie intakes also vary across the world. According to the National Health Service (NHS), UK, the average male adult needs approximately 2,500 calories per day to keep his weight constant, while the average adult female needs 2,000. US authorities recommend 2,700 calories per day for men and 2,200 for women. It is interesting that in the UK, where people on average are taller than Americans, the recommended daily intake of calories is lower. Rates of overweight and obesity among both adults and children in the USA are considerably higher than in the United Kingdom.
The NHS stresses that rather than precisely counting numbers (calories), people should focus more on eating a healthy and well balanced diet, being physically active, and roughly balancing how many calories are consumed with the numbers burnt off each day.

According to the United Nation's Food and Agriculture Organization (FAO), the average person's minimum calorie requirement per day globally is approximately 1,800 kilocalories.

How many calories do I need per day?

The Harris-Benedict equation, also known as the Harris-Benedict principle, is used to estimate what a person's BMR (basal metabolic rate) and daily requirements are. The person's BMR total is multiplied by another number which represents their level of physical activity. The resulting number is that person's recommended daily calorie intake in order to keep their body weight where it is.

This equation has limitations. It does not take into account varying levels of muscle mass to fat mass ratios - a very muscular person needs more calories, even when resting.

How to calculate your BMR

• Male adults
  66.5 + (13.75 x kg body weight) + (5.003 x height in cm) - (6.755 x age) = BMR
  66 + ( 6.23 x pounds body weight) + ( 12.7 x height in inches ) - ( 6.76 x age) = BMR


• Female adults
  55.1 + (9.563 x kg body weight) + (1.850 x height in cm) - (4.676 x age) = BMR
  655 + (4.35 x kg body weight) + (4.7 x height in inches) - (4.7 x age) = BMR