Everyone is always looking for the quickest and easiest solution to just about everything, weight loss included. Losing weight isn't a quick or easy process. If you want a time frame, think about how long it took you to gain the weight you're now trying to lose. If it took 6 months to gain, it's not realistic to try and lose it in 6 weeks. While losing weight quickly is technically possible, it's very unhealthy for a number of reasons.
Too Much Change
Losing any amount of weight requires sacrifice. To lose 2 pounds per week (the fastest healthy weight loss), you need to create a deficit of 1,000 calories per day. That means that you need to eat 1,000 calories less than you burn every single day. This is already a big deficit that will take some time to get used to.
Now imagine trying to lose even more weight, for example 4 pounds per week. A weight loss at that rate would require a 2,000 calorie per day deficit. That means that if your body burns 3,000 calories per day, you'd only be able to eat 1,000 calories to achieve a weight loss of 4 pounds per week. Not only is that very difficult to get used to, it's also unhealthy. At 1,000 calories, it's almost impossible to get all the nutrients (vitamins and minerals) your body needs to properly function.
Next you need to implement your calorie deficit. If you're still thinking about trying to lose 4 pounds per week, good luck living with a 2,000 calorie per day deficit. You'll have to cut down on your food intake, exercise a lot more and do this over a long period of time for sustained weight loss. If you're not used to eating healthy or exercising, this will be very hard on you mentally. After a few days of eating 1,000 calories and exercising for two or more hours, you'll being to feel lethargic and you'll start to crack.
Quick Change = Temporary
All of the tough changes you've been trying to force onto your body won't stick for very long and before you know it, you'll be back to your old habits because you didn't give yourself an adequate amount of time to get used to your new lifestyle. Reducing calories, exercising more and cutting out some of your favorite foods isn't easy. You simply won't be able to handle all of the above in such a short period of time. These quick diets in which you attempt to lose a large amount of weight in a short period of time are referred to as crash diets.
Crash diets aren't long term solutions to weight problems. They work by severely limiting your calorie intake for a few days in hopes of some quick weight loss. The huge initial weight loss is usually in the form of water weight and not body fat. As soon as you go back to your normal eating habits, the weight will come back on and you'll probably end up weighing more than when you started your crash diet.
The Bottom Line
The only healthy way to lose weight is at a slower pace. By losing weight slowly, you'll feel more energetic, be healthier and solve your weight problem permanently. You won't have to keep turning to short term fixes. Your deficit should be no larger than 1,000 calories per day. Instead of cutting excessive calories to reach your deficit, increase your physical activity to burn more calories. While quick weight loss may be gratifying today and tomorrow, you won't be solving any of your health problems, you'll only be making them worse.