A knowledge of the likely magnitude of day-to-day variations in body-weight is of great value for the interpretation of metabolic balance studies. Durnin (1961) found day-to-day changes of up to I kg in a group of forty-four young men living under controlled conditions. The procedure for weighing was highly standardized : 'the men were naked, the measurements were done immediately on their rising from bed in the morning, before any food or drink h.ad been taken, and after the urinary bladder

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... been emptied.' Edholm (1961) and L4dam, Best & Edholm (1961)) following a similar routine, weighed sixty-four soldiers (174-229 years) each day for periods of 7 days and of up to 7 weeks. They found, in more than 1700 weighings, a weight change of over 0-5 kg on 30% of the occasions, and of over I kg on 6%. Khosla & Billewicz (1964) , from a study of day-to-day weight changes for from 30 to 40 days in nineteen subjects of varying size, age and sex, showed that the extent of the daily fluctuations of body-weight was related to the body-weight itself, and that the maximum day-to-day change rarely exceeded 1-5 % of the body-weight. The opportunity seldom presents itself to follow adequately the daily weights of a group consisting solely of women. Many workers have reported weight trends with the menstrual cycle, but rarely have the subjects been living in the same environment, been following the same occupation, and been weighed under carefully controlled conditions. The subjects of Klein & Carey (1957) were hospital personnel and were weighed after breakfast; those of Fortin, Whittkower & Kalz (1958) were public service employees and were weighed on arrival at work. Body-weights were not always recorded on every consecutive day; some were weighed on work days (Chesley & Hellman, 1957), others on every 2nd day (Fortin et al. 1958) , or every 3rd day (Danforth, Boyer & Graff, 1946). Thomas (1953) weighed a group of fourteen women medical students before breakfast, without clothes and after voiding, but presented the results as weight profiles only. Taggart (1962) carried out a careful study on one female subject: the change in body-weight from one day to the next ranged from -0.81 to +0-77 kg for the first experimental period of 80 days, but varied from -0.43 to +0.31 kg in the second period of 35 days when 'the food intake was kept constant and the activity as constant as was consistent with ordinary duties at work and at home'. Daily weights have now been followed in women students living and eating in the same residential hall and attending similar courses at the university. The subjects were weighed each morning in a standard manner during the winter term. No at https://www.cambridge.org/core/terms. https://doi.