I have helped a lot of people lose weight, and I usually suggest that slow and steady weight loss such as 1-2lb’s a week is sustainable weight loss, however there are some people that are just too impatient or who want dramatic results in order to get in shape for a wedding or to look good on holiday. These people may be the ones who would go on a juice fast, crash diet for 2 weeks, or try the master cleanse (the maple syrup diet). These diets may work whilst you are on them, but I do not believe they are a healthy or sustainable ways to lose weight.
Most of the time as soon as you stop the diet you put the weight back on with a little more to boot. This happens because these diets really screw up your hormones and metabolism. When you go in to a state of famine (dieting) your body reacts by up regulating your lipogenic (fat storing) enzymes, your thyroid slows down reducing your metabolism, and you start to produce more stress hormones. Your detoxification also slows down as your liver needs a whole host of vitamins, minerals and amino acids (the breakdown products of protein) to clean your body and eliminate toxins through the bowel and bladder.