and food content of these factors but do not include additional quantities added in preparation or consumed at the table. In a future study we may evaluate the risk from fructose, sucrose, potassium, alcohol, and caffeine in these women, but these have been inconsistently reported as risk factors in the literature and so are not included in our current analyses. BMI, physical activity measurements of METs per week, and the calibration of energy intake are all related to weight, and this may partially attenuate the effect of each of these variables. METs are estimates of activity intensity and duration but do not take into account efficiency of movement or strength; they do not equate to calories burned because they do not account for resting metabolic rate or occupational physical activity. Finally, stone composition and 24- hour urine studies were not performed on these patients, and thus the effects of diet and exercise on urinary parameters are unknown.
In conclusion, mild to moderate amounts of weekly phy- sical activity are associated with a decreased risk of de- velopment of kidney stones in postmenopausal women. This effect is driven primarily by the amount of physical activity rather than the intensity of exercise. In addition, higher total dietary energy intake is associated with an increased risk of incident nephrolithiasis, but a low dietary energy intake does not decrease the risk of kidney stones. These effects are in- dependent of the contribution of BMI and other nephroli- thiasis risk factors, including dietary intake of water, sodium, animal protein, and calcium. These findings have important clinical implications regarding dietary counseling and re- inforcing patient efforts to lose weight and increase physical activity.