I doubt that any doctor would support a weight loss goal of 25 lbs. per month unless you would be morbidly obese. Most of the weight you would lose would be water weight anyway, and it would come back quickly. I recently consulted with a weight loss doctor who prescribed a sensible diet (moderately low carb) and the medication Adipex. That combination was magic for me. The diet resulted in rapid weight loss, and the prescribed medication made it easier for me to follow the diet. I did have to follow up often with my physician, but the results are worth it!
Losing 20 lbs a month is not a reasonable goal, no matter how obese you are. Safe weight loss is 1-2 lbs/week.