In my opinion I hear too many people say they are on diets. They want the quick fix to taking weight off, often with very little knowledge about dangerous side effects and the longer term to coming off the diet.
Losing weight is easy on a diet, but keeping it off when you have made so many drastic changes can be where people come unstuck. Any Diet programme where you are bound by time scale suggests you are going to fall back into old habits once the programme is finished. A 10 Day juice cleanse, guaranteed 10Lb weight loss. You may well lose that but as soon as you start eating solid food again you will put the weight straight back on.
You body works on a fight or flight mechanism. If you don't feed yourself you break down all available energy in terms of carbs, fats and proteins to try and maintain efficient calories to help you function. Should you deplete your body of a certain food group such as carbs, when you reintroduce them your body saturates itself with them and holds on to them, storing them as fats as it does not know when you might eat them again.
For me I have always been an advocate of having healthy balanced nutrition. Not depriving yourself of any food group, rather eating them in moderation. Feeding yourself for the activity you have in the day. Calorie balance is the key to losing weight, maintaining weight or gaining weight.