Profound hypophosphataemia in patients collapsing after a “fun run”

total (non-lactational) energy expenditure comprises resting metabolic expenditure, energy expenditure induced by dietary intake, and active metabolic expenditure as a result of physical activity. It might therefore be suggested that the apparent discrepancy in energy balance between the two groups could be due to increased active metabolic expenditure on the part of the bottle feeders: whether this is the case I know not but the deficit of 2 to 3 MJ/day (the estimated energy requirement for lactation) could easily be accounted for by a moderate increase in physical activity of the bottle feeding group. Perhaps increased activity and a busy lifestyle accounted for the difficulty in recruitment of bottle feeders for the trial? Furthermore, if -it is claimed that lactation brings about changes in glucose and lipid metabolism, why did the authors not present information on respiratory quotients (or, more correctly, respiratory exchange ratios) in the resting and postprandial states? Such information must surely be easily obtainable from their indirect calorimetric data and might well help substantiate such a claim. JoHN D CANNON Deoarmeat of Surgery, Nineweils Hospital and Media School, Dundee DDI 9SY