What weight can an 18 years old girl lose in a week with a bit more intense diet?

Doctor say it's bad to more npthen 1-2lbs a week but with a intense duet I wuld say 5. Exspecially if she's going to the gym n eating healthy...if it's her first week on the diet or exercise program etc. And she has a good amount if weight to lose shell shed her water weight the frusta week so mybe even more then five lbs..