The energy requirements of an individual can be defined as that amount of energy intake in relation to expenditure which is least likely to result in obesity or hea disease to which is most likely to prolong active life. The energy allowance required for an individual consists of three components: 1. The energy that is required for the purpose of basal metabolism which is about 1kcal per hour for every kg of weight of that individual adult. 2. The energy that will be necessary to pursue the daily activities sitting, standing, dressing and climbing stairs. 3. The energy expenditure that will be required to carry out the occupational work. A women requires an additional 300 Kcal for each day throughout the pregnancy. Ref: Park's Textbook of Preventive and Social Medicine, 19th Edition, Pages 502 - 503.