Sometimes, just for a short term boost, you will need to lose a few pounds fairly fast. While this is not a recommended way to go for the long term and for sustained weight reduction, it is all right to do it in the short term as a short burst if you need to attend a special occasion and get into a smaller size dress or whatever.
There are some things that you can do to achieve this kind of rapid loss of a few pounds, but if you want to keep them off once you have lost them, you are going to have to switch to a different strategy.
But first, you need to remember that losing weight fast is not a good idea unless it is a bit of an emergency, when you can bend the rules a little to suit your immediate needs. Say you need to lose several pounds in two weeks or similar. To do this, you will have to be pretty strict with yourself and realize that you are going to feel pretty hungry while you are doing it!
The first thing you are going to have to do is a serious diet shift from whatever you are eating to something that is uber low in calories but still provides enough nutrients that your metabolism doesn't slow down. That means a shift away from most unhealthy carbs and all sweet stuff to a diet high in protein and dietary fiber with some monounsaturated fats being the best foods for weight loss.
Out will have to go all bread, pasta, rice, potatoes and sweet things like cakes, pie, cookies etc. But you probably already knew that, or at least feared it!
In comes good healthy high protein stuff like egg whites (not yokes), lean steak, skinless chicken breast, cottage cheese. You can eat some green leafy veggies such as cabbage, kale, and broccoli. Salad leaves (lettuce, raw spinach) and celery are allowed. You can flavor food with onions, garlic, ginger and any fresh herbs you like.
You have to drink at least two pints of plain water a day. No soda, not even diet soda, no flavored drinks, no alcohol, no sports drinks. Fresh fruit juice (orange, grapefruit or apple) at breakfast is okay. Supplement with a good multivitamin so you don't go without nutrients.
While you're about changing your diet to a tough one, you must exercise. It's no good hoping a diet will do it for you. If you want to lose weight fast and make it count, you must get some exercise in! If you haven't done any exercise for a while, you are going to have to start slow and build up each day to avoid injury.
You will have to get to a stage where you can maintain a fairly high rate of resistance training or aerobic workout for half an hour or more. That's because you need to force your body to burn fat.
It will do that as long as you use up all your blood sugar in the first 20 minutes which forces your body to process fat to give you more so your muscles can continue working. Exercise every day and do a variety of exercises from fast walking, swimming, running to resistance training in the gym if you can, or get a home stepper machine and use that!
The idea is to eat a low calorie diet of 1500 calories or less a day, while training like you want to burn 3000 a day. This will cause fairly rapid weight loss and is something you can maintain if you want to keep the weight off short term, but not long term. Remember that weight loss should be slow normally and this is just a quick fix option.
You will be able to relax some on the diet and exercise regimen over time as you aim to maintain the new weight and body size.