Your doctor is rubbish!
all that will happen is you'll loose a lot of weight too quickly and your skin won't shrink with you, if that makes sense.
Take note of what you eat in a normal day; when you next go shopping, opt for food with lower calorie content, and you cans still eat normally, but less calories.
If you dont want to do that, work out how many calories you eat in the average day, say its like 2000 calories, the recommended amount, reduce that amount SLOWLY, so week one, go for 1800cals, week 2 1600, week 3 1400, and so on, its much easier to loose weight if you go through it slowly, where as if you jump straight to 1000cals, your more likely to binge out and fail.