For the purpose of computing the total nutrient needs of the population at the national level, the concept of reference man and women is used.
Reference man and reference women are defined on the basis of body weights of well-nourished healthy adults in each country who have satisfactory growth during their childhood and are currently leading a healthy and active life.
Reference man is between 18-29 years of age, and weights 60 kg with a height of 1.73 m with a BMI of 20.3. He is free from disease and physically fit for active work. On each working day, he is employed for 8 hours in occupation that usually involves moderate activity. While not at work, he spends 8 hours in bed, 4-6 hours in sitting and moving about 2-4 hours in walking and in active recreation or household duties.
Reference women is between 18-29 years of age, non-pregnant, nonlactating and weighs 55 kg with a height of 1.61m and a BMI of 21.2, is free from disease and physically fit for active work; on each working day she is engaged in 8 hours of occupation which usually involves moderate activity, while when not at work she spends 8 hours in bed, 4-6 hours in sitting and moving around in light activity and 2 hours in walking or active recreation or household chores.