Liquid diets often work for weight loss, solely based on the principle of "calories in-calories out" -- meaning that if you consume fewer calories than you burn, you will lose weight. Because liquid diets reduce your caloric intake, you lose weight. They're also convenient, particularly if you indulge in commercial liquid options. While they can be effective, however, liquid diets are not always a healthy weight-loss option. If you decide to go on a liquid diet -- or are ordered to for medical reasons -- do it as smartly as possible to minimize damage to your health.
Talk to Your Doctor
Before you go on a liquid diet, talk to your health care provider. Certain people, such as pregnant or nursing women, or diabetics who take insulin, should not try a liquid diet. If the doctor approves, meet with a registered dietitian. He can help you come up with ideas on how to do the diet safely, as well as offer up commercial options that might make the diet more convenient. It's important to get all the recommended vitamins and minerals each day, as well as stay within safe caloric ranges. A review of studies in the U.S. Department of Agriculture's National Evidence Library determined that there's no conclusive evidence to support that getting calories in liquid form -- with the exception of soup -- has an effect on body weight or energy intake.
Choose a Type
Medically necessary liquid diets, such as before or after surgery, range from allowing all liquids and semiliquid foods, including fruit juices, soup, soda and gelatin, to just liquids you can see through. The latter category includes tea and sports drinks. Liquid diets for weight loss, however, are much more flexible. According to WebMD, potential liquid diets include those that replace all of your meals with fruit or vegetable juices or shakes to those that replace just one or two meals with liquids and allow for a healthy dinner or snack bar. The latter option is more likely to teach you healthy habits, according to WebMD, but no matter which you choose, select a plan that's not too low in calories. Your doctor can help you figure out a safe minimum calorie intake. If you choose a liquid diet supplement, says registered dietitian Diana Sugiuchi on Healthline, pick one that has 100 percent of the recommended vitamins and minerals, at least 60 grams of protein and 25 grams of fiber, along with a healthy source of fat.
Make It Short-Term
If you're undergoing a liquid diet to jump-start weight loss, only do it for a couple days, recommends Sugiuchi. This short-term period is unlikely to hurt you. But a long-term liquid diet for weight loss is not optimal for success, she says.
In addition to stocking up on caffeine-free tea, chicken or vegetable broth, water and juice, you can get in nutrients on a liquid diet by using your blender. Registered dietitian Martha Rosenau on Health.com recommends combining milk -- cow's, almond or soy -- with yogurt, protein powder and a banana and blending into liquid form. Talk to your nutritionist or doctor about what other liquids are suitable for your particular variety of diet.
Safety and Weight Gain
When going on a liquid diet, you risk wreaking havoc on your metabolism if you consume too few calories. Diets in which you consume just 400 to 800 calories a day should only be done under medical supervision. If you don't get the recommended amount of nutrients, you risk fatigue, dizziness, hair loss, gallstones and heart damage. Your body also will lower your metabolism to conserve energy, so once you return to a regular way of eating, you'll likely find the weight creeping back on. A diet that encourages changing your lifestyle to healthier habits is more likely to result in long-term weight loss.