I though that these were commonplace observations. Diurnal variation in height was first reported in the early 18th century (it is a very early anthropometric finding and one with a "believe it or not" charm). You can try this yourself ... measure your colleagues in the morning and again in the evening. You'll probably see a 8 - 10 mm mean drop in their height. As for weight ... you can do this yourself ... weigh yourself before and dafter drinking 500 ml of water. Your weight will increase by 0.5kg. You could weight yourself before and after a bowel movement and find you lose (on average) just above 0.2 Kg. Weigh yourself before and after eating your main meal. You gain weight. The A. lumbricoides reference was, if I recall correctly, from Manson's Tropical Diseases (not to hand at present so I cannot confirm this) which describes the mean mass of the A. lumbricoides load in heavily parasitised children. The issue here is "heavy parasitism". Hydration and weight is another obvious thing. A child is about 70% water by mass. Any change in hydration changes overall mass considerably. This is a lot of interaction going on since dehydration is often caused by diarrhoea, vomiting, fever which is often accompanied by reduced food and water intake ... the kid has an empty stomach and bowel (low mass) and dehydration by diarrhoea and by fever sweating. Weight loss is also likely due to the energy requirement of the response to infection when energy intake is reduced. Hydration and weight is a current topic in sports medicine where "voluntary dehydration" is a tactic employed by (e.g.) boxers to box in a lower weight category. It's a form of cheating.