What causes kidney stones?

I recently had sharp pains in my loins. An ultrasound showed that I have kidney stones. Kindly let me know what could have caused this. I am a healthy 40-year-old man and I fast frequently in line with my religious faith.

Jemila  (by SMS)

Although Kidney (Renal) stones occur more in male in the young or middle age, there are other different theories and opinions on the reasons for stone formation: Some people are more susceptible to the formation of renal stones than others and genetics play a role. Some genetic disease increases the risk for formation of renal stones. Some people are more exposed to kidney stones, and this happens in the tropics, where residents are exposed to hot areas and dryness and the urine become more concentrated to form the nucleus for the stone. Synthetic calcium-rich food may increase the risk of developing kidney stones. The people who use diuretics or consume many antacids containing calcium could increase the amount of calcium in the urine and increase the risk of stone formation. In addition, fasting causes dehydration and a higher incidence of stone formation. These days, those who fast are advised to take some water to avoid the high incidence of kidney stone formation that has been confirmed among those who fast regularly.