In the last few years, liquid-based diet plans have emerged as a popular way to expedite weight loss. They encourage dieters to replace regular meals with a liquid alternative in order to shed weight fast. The mass appeal of these weight loss programs is undeniable given the sheer number of celebrity endorsements and television infomercials. But is a bang-for-your-buck approach to nutrition really sustainable? And, for that matter, is it safe?

What Are Liquid Diets?

Like the name suggests, liquid diets mean you’re getting all, or at least most, of your calories from drinks. Some liquid diets are limited to fruit or vegetable juices or shakes that replace all of your meals, taken three or four times a day. You do some of these diets on your own. Others need medical supervision. Other types of liquid diets replace just one or two meals (usually breakfast and lunch) with drinks, and then you eat a healthy dinner. You may also get snacks on some of these plans.

The liquid die food can be combined somewhat later in the diet with low-calorie and high-fiber diet. On the other hand, the low-calorie liquid diet plan consists of medically relevant liquid diets that only provide 500 to 800 calories a day and is to be supported with solid food in a few days. This type of liquid diet is suitable for those who want to lose weight fast and for long.

Do they work?

Liquid diets work to help you lose weight because they provide so few calories each day. If you’ve decided on the liquid-only diet approach, you’ll consume just 600 to 700 calories each day — enough to lose 3 lbs. or more per week. If you decide to eat a small dinner as part of your diet, you’ll still be consuming just about 1,000 calories a day, which should lead to weight loss of about 2 lbs. each week. When beginning your diet, most of your weight loss should come from your fat stores. However, you’ll run into problems if you continue your diet for a month or longer. Unfortunately, when you excessively restrict calories for a long duration, your metabolism slows and your body may begin to break down muscle instead of your fat stores. To combat this problem and lose as much fat as possible while sparing your muscle tissue, exercise regularly as you follow the liquid diet.

The Dangers

Liquid diets used for weight loss and fat loss have a number of health concerns, especially if you follow one for more than a few weeks at a time. Most alarmingly, very low-calorie diets, such as liquid diets, can affect the electrical signals that control your heartbeat, potentially leading to dangerous heartbeat irregularities. If you’ve ever been diagnosed with a heart arrhythmia, you shouldn’t follow this type of diet. In addition, liquid diets can cause constipation and other gastrointestinal upsets, dizziness, and gallbladder problems, including gallstones. You also may feel more tired than normal while following a liquid diet since you won’t be consuming the calories you need to keep up your activity level.

Liquid Diet Deficiencies

A juice fast can provide you with generous phytonutrients, carbohydrates, and vitamins — but is missing essential fatty acids, which support a healthy brain, and protein, to support muscle. Medically supervised liquid diets require hospitalization or regular checkups to ensure complications are not developing; a very-low-calorie liquid diet should not be followed for more than 12 weeks, even in a medical setting. Most people do not need to follow a very low-calorie diet and should follow a whole foods low-calorie diet to lose weight.

Liquid diets also fail to teach you how to craft meals that will support any weight loss in the long term. At some point, you’ll start to eat whole foods again; if you don’t have good, healthy habits in place, you could end up regaining any lost weight and possibly more when you return to old ways of eating.

Keeping It Off After a Liquid-Only Diet

Most liquid-only programs gradually transition you to self-made meals. During the program, you learn how to portion foods and meals properly to prevent overeating once you return to solid foods. You also learn how to make healthy food choices and how to build nutrient-packed meals using whole foods. Without learning these crucial tools to keep the weight off, you risk regaining what you lost and undoing all of the hard work. You’ll learn how to make sensible changes and how to have your favorite foods — such as birthday cake or pizza — in moderation, as well as how to make healthier versions of those foods.