For that weight loss you must have reduced your diet by and burned 54,000 calories in the month. That's 1,800 calories less per day for a 30 day month. So assuming your exercise was burning off 500 calories per day, the other 1,300 calories was from reduced intake and maintenance calories for rest of day. Generally classed as unhealthy as muscle is burned off rather than fat if done too quickly (i.e. more than 34,000 calories for the 30 day month).