Liquid diets are safe unless they lack essential nutrients, notes WebMD. Some people go on low-calorie liquid diets that only provide between 400 and 800 calories each day. These are particularly dangerous in terms of lacking necessary nutrients. Side effects can range from fatigue to hair loss and heart damage.
Another risk of a liquid diet is inadequate fiber. Whole vegetables and fruits provide significantly more fiber than juices, and staying on a liquid diet can lead to constipation. People who do not get enough protein because they are on a liquid diet can lose muscle mass. Managing nutrient balance with a liquid diet is just as important as it is with a typical diet, reports WebMD.
Liquid diets are sometimes a doctor's recommendation ahead of certain medical procedures as well as for people who are obese but need to lose some weight before they can have weight loss surgery. However, these liquid diets happen under medical supervision, as stated by WebMD.
Safe liquid diets do work for some people, just like any other weight loss strategy that contributes fewer calories than what a person burns. However, the metabolism often slows down with calorie consumption to preserve energy. Those who go back to their old eating habits after the liquid diet ends are likely to gain all of the weight back, according to WebMD.