Diet plans. Most effective diet plans are those that involve permanent changes in eating habits. Portion size restriction, calorie restriction, low bad fats (animal, trans), low glycemic index foods (avoid white bread/rice/pasta/potatoes). Combine these with exercise program: walking is the safest exercise—low impact, easy on joints. Commercial plans like jennie craig & weight watchers seem to work well.
Stones. Plenty of fluids. Avoid foods high in oxalates or phytates. It all depends on the type of stones you have.