Hi, I have tried some of the liquid diets :
Hollywood juice diet - buy a bottle of aforementioned juice. Mix with water and that's your food for one or two days. Is a short term rapid weight loss system for people who need a short sharp burst. I normally drop over a stone but am a hefty guy
Lemon Detox- used to love this. Madal Bal syrup, lemon juice, cayenne pepper in water sit back and detox. The book I read treated this as a cleanse for people who are taking it slow. Definitely not recommended to hit the exercise hard. Again weight loss is pretty rapid. If you are taking time out from your day to day and spending some quality me time this can be a good option. You can in theory keep it going for months but I have only ever managed a week. Hard to sustain when doing the daily routine.
Juice Cleanse - fresh veg,fruit and herbs. Get juicer, loads of recipes available. Made famous by that Joe documentary. Had good results health wise with this. Find it easier when just using for one meal like breakfast. Lots of science reckons the fruit/veg is a balanced food as nature intended it and by discarding the husks you are loosing the fiber and a lot of the health benefits and essentially extracting the sugars.
The mineral/smart water fasting. Basically a starvation fast giving your body basic minerals and vits through smart water. Again there is a good documentary on this by a guy who set the world record and lost tons of weight. Done this for a week, again best in a relaxed environment. Sadly one of the best books on fasting was written by a serial killer that used to starve her victims to death in a health farm and steal all there goods.
I hesitate to mention the next one as is used a lot by extreme dieters but there is the potassium broth diet where varying days you just simmer various veg sieve, and drink the juice as a nutrient rich broth. Thankfully therapy got me before I got into this one. Although please do not take that as a judgement on anyone that is doing this. Just please check with your doctor occasionally get your bloods checked for deficiencies. No point spending years getting the body you want then having your bones collapse or lose your hair.
I have been fad dieting on and off for years and the only thing to say is after each one I have put the weight back on and a little bit more. I own hundreds of books/ dvds on the subject as I used to overeat then compulsively buy new systems thinking this would be the one. It nearly killed me. Now I eat healthy meals judged for a man of the weight I want to be. I still watch my processed foods and carbs and try to food combine as the evidence seems to point this has an effect. However I still get a massive kick from losing weight and it is difficult not to get carried away trying some new thing.
Hope some of that helps.