There are an increasing number of diet products that make wild claims on weight loss either alledgely substantiated by celebrities and/or dragons den. Equally miracle heating that costs little to run and heat your home. Twitter, Facebook or multiple dodgy websites and blogs are not a reliable sole source for authentication.
There are foods that can help your metabolism, and there are approved diet pills that can help block Fat being absorbed, such as Orlistat Xenical which is a prescription drug and can assist as part of a calorie controlled diet and exercise, but only help supplement your efforts. They do not magically drop large volumes of weight off in a short period of time by themselves.
Many of us want to to lose weight and as fast as possible. It is possible to shift weight by reducing calories, changing the types of foods we eat and importantly exercise and there are many ways to try this including intermittent fasting.
It helps to try and find something that works for you. The more effort you put in generally the bigger rewards, but plateaus (where weight loss stops or even go up) are common too, you have to work through these. There are tips on this too.
The biggest dangers are giving up, breaking your own diet and exercise rules too often and worst of all not maintaining your diet / exercise after weight loss.
Your weight maintenance post diet should be easier, but many of us are trying to break the habits of a lifetime so it's very easy to go off the rails.
Regular weighing and tweaking our diet and exercise, if needed, can help keep that weight off for good.
Good Luck to those trying to lose weight, significant change can be seen in 3-6 months, but may take at least 1-2 years, depending on how much you have to lose.