Losing weight (fast) usually means "temporarily".
Anyone who wants to lose 10lbs in a couple of weeks could do so by radically changing what and how much they eat. Avoid carbs, sugar, soda, alcohol, starches, and only drink water.
Eat mostly proteins and main course items should not be bigger than what fits in the palm of one of your hands. Last but not least workout 5 days per week in one of those rubberized sweat suits and possibly use a dry sauna for 30 minutes a day.
As I said this would only be a (temporary solution) for someone trying to lose weight quickly to attend an event of some kind. (Take multi-vitamins and drink plenty of water)
I'm not a doctor or dietician. I speak only from (my experience).