Plans called "detoxification diets" either promote or restrict certain foods to provide specific nutrients in high quantities. These can be useful for addressing some nutritional problems, but they're far too specific to be used as general cure-alls. For example, for a person with low vitamin A, a juice diet might be helpful. But for someone high in vitamin A, juicing could be disastrous. And regardless of personal nutrition, maintaining a juice diet over multiple weeks is likely to compromise the immune system due to a lack of essential fats and proteins. Therein lies the problem with all these fast-moving diets — whether you're cutting calories or food groups, extreme diets are a shock to your system. There are well-established rates of healthy weight loss motivated by both diet and exercise that account for genetic and medical differences. And staying on those timelines requires a dietary lifestyle that's sustainable. In fact, some of the worst side effects of extreme diets are rarely discussed since so few people stick with them, it also bears mentioning that many societies have unhealthy relationships with weight and people are often pressured to diet for reasons other than health or happiness. So rather than trying to lose weight fast, we should all be taking our time to figure out what the healthiest lifestyle is for ourselves.