A very-low-calorie diet (VLCD), also known as semistarvation diet and crash diet, is a type of diet with very or extremely low daily

food energy Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscular activity. Most animals derive most of their energy from aerobic respiration, namely combining the carbohy ...

consumption. Often described as a

fad diet A fad diet is a diet that becomes popular for a short time, similar to fads in fashion, without being a standard dietary recommendation, and often making unreasonable claims for fast weight loss or health improvements. There is no single defi ...

, it is defined as a diet of per day or less. Modern medically supervised VLCDs use total meal replacements, with regulated formulations in Europe and Canada which contain the recommended daily requirements for

vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...

minerals In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed ...

trace element __NOTOC__ A trace element, also called minor element, is a chemical element whose concentration (or other measure of amount) is very low (a "trace amount"). They are classified into two groups: essential and non-essential. Essential trace elements ...

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

and electrolyte balance.

Carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or m ...

s may be entirely absent, or substituted for a portion of the protein; this choice has important metabolic effects. Medically supervised VLCDs have specific therapeutic applications for rapid

weight loss Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat ( adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other co ...

, such as in morbid

obesity Obesity is a medical condition, sometimes considered a disease, in which excess body fat has accumulated to such an extent that it may negatively affect health. People are classified as obese when their body mass index (BMI)—a person's ...

or before a bariatric surgery, using formulated,

nutrition Nutrition is the biochemical and physiological process by which an organism uses food to support its life. It provides organisms with nutrients, which can be metabolized to create energy and chemical structures. Failure to obtain sufficient ...

ally complete liquid

meal A meal is an eating occasion that takes place at a certain time and includes consumption of food. The names used for specific meals in English vary, depending on the speaker's culture, the time of day, or the size of the meal. Although they c ...

s containing 800 kilocalories or less per day for a maximum of 12 weeks. Unmonitored VLCDs with insufficient or unbalanced nutrients can cause sudden death by cardiac arrest either by starvation or during refeeding.

Definition

Very-low-calorie diets (VLCDs) are diets of or less energy intake per day, whereas low-calorie diets are between 1000-1200 kcal per day.

Health effects

The routine use of VLCDs is not recommended due to safety concerns, but this approach can be used under medical supervision if there is a clinical rationale for rapid weight loss in obese individuals, as part of a "multi-component weight management strategy" with continuous support and for a maximum of 12 weeks, according to the

NICE Nice ( , ; Niçard dialect, Niçard: , classical norm, or , nonstandard, ; it, Nizza ; lij, Nissa; grc, Νίκαια; la, Nicaea) is the prefecture of the Alpes-Maritimes departments of France, department in France. The Nice urban unit, agg ...

2014 guidelines. The US dietary guidelines recommend that VLCDs can be used for weight loss in obese individuals only in limited circumstances and only under supervision by experienced personnel in a medical care setting where the individual can be medically monitored and high-intensity lifestyle intervention can be provided. For the general public, VLCDs are not recommended due to low evidence. As there are considerable risks of starvation with an inadequately composed or supervised VLCD, people attempting these diets must be monitored closely by a physician to prevent complications. VLCDs appear to be more effective than behavioral weight loss programs or other diets, achieving approximately more weight loss at 1 year and greater sustained weight loss after several years. When used in routine care, there is evidence that VLCDs achieve average weight loss at 1 year around or about 4% more weight loss over the short term. VLCDs can achieve higher short-term weight loss compared to other more modest or gradual

calorie restricted diet Calorie restriction (caloric restriction or energy restriction) is a dietary regimen that reduces intake of energy from caloric foods & beverages without incurring malnutrition. "Reduce" can be defined relative to the subject's previous intake be ...

s, and the maintained long-term weight loss is similar or greater. VLCDs were shown to reduce

lean body mass Lean body mass (LBM), sometimes conflated with ''fat-free mass'', is a component of body composition. Fat free mass (FFM) is calculated by subtracting body fat weight from total body weight: total body weight is lean plus fat. In equations: :LBM&n ...

. Combining VLCD with other obesity therapies yield more effective results in weight loss. Low-calorie and very-low-calorie diets may produce faster weight loss within the first 1–2 weeks of starting compared to other diets, but this superficially faster loss is due to glycogen depletion and water loss in the

and is regained quickly afterward. VLCDs are efficient and recommended for liver fat reduction and weight loss before bariatric surgery. A 2001 review found that VLCD has no serious harmful effect when done under medical supervision, for periods of 8–16 weeks with an average weight loss of 1.5-2.5 kg/week. However, VLCD may increase the risk of developing

gallstone A gallstone is a stone formed within the gallbladder from precipitated bile components. The term cholelithiasis may refer to the presence of gallstones or to any disease caused by gallstones, and choledocholithiasis refers to the presence of mi ...

s if the fat content of VLCD is not sufficient, but data is lacking to know the precise amount of fat that is necessary to avoid gallstones formation. Indeed, dietary fat stimulates gall bladder contraction, thus, if following a fat-free VLCD, the bladder does not empty. Another potential side effect is

constipation Constipation is a bowel dysfunction that makes bowel movements infrequent or hard to pass. The stool is often hard and dry. Other symptoms may include abdominal pain, bloating, and feeling as if one has not completely passed the bowel movement ...

(depending on the

fiber Fiber or fibre (from la, fibra, links=no) is a natural or artificial substance that is significantly longer than it is wide. Fibers are often used in the manufacture of other materials. The strongest engineering materials often incorpora ...

content of the diet). VLCD were not found to increase food cravings, and on the contrary, appear to reduce food cravings more than low-calorie diets. Previous formulations (medical or commercial) of carbohydrate-free very low calorie diets provided 200–800 kcal/day and maintained protein intake, but eliminated any carbohydrate intake and sometimes fat intake as well. These diets subject the body to starvation and produce an average weekly weight loss of . However, the total lack of carbohydrates avoids

protein sparing A protein-sparing modified fast or PSMF diet is a type of a very-low-calorie diet (<800 kcal per day) with a high proportion of protein calories and simultaneous restriction of carbohydrate and fat. It includes a

and thus produce a loss of lean muscle mass, as well as other adverse side effects such as increased risks of

gout Gout ( ) is a form of inflammatory arthritis characterized by recurrent attacks of a red, tender, hot and swollen joint, caused by deposition of monosodium urate monohydrate crystals. Pain typically comes on rapidly, reaching maximal intens ...

, and

electrolyte imbalance Electrolyte imbalance, or water-electrolyte imbalance, is an abnormality in the concentration of electrolytes in the body. Electrolytes play a vital role in maintaining homeostasis in the body. They help to regulate heart and neurological function, ...

s, and are thus disadvised. Total diet replacement programs are the modern formulations regulated in Europe and Canada to ensure the recommended daily intake of necessary nutrients, vitamins and electrolyte balance. Compared to older VLCD formulas, the total diet replacements better preserve lean body mass, reduce known side effects and improve . Unmonitored VLCDs with insufficient macronutrient and mineral intake have the potential to cause an

and sudden death via

ventricular tachycardia Ventricular tachycardia (V-tach or VT) is a fast heart rate arising from the lower chambers of the heart. Although a few seconds of VT may not result in permanent problems, longer periods are dangerous; and multiple episodes over a short perio ...

either by starvation or upon refeeding.

History and society

The earliest data on VLCDs come from the aftermath of

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

, when several scientific experiments were undertaken to examine what conditions could lead to starvation and how to rehabilitate safely to eating, such as the

Minnesota Starvation Experiment The Minnesota Starvation Experiment, also known as the Minnesota Semi-Starvation Experiment, the Minnesota Starvation-Recovery Experiment and the Starvation Study, was a clinical study performed at the University of Minnesota between November 19, 1 ...

, in an effort to reduce the casualties caused by famine following the war. VLCD is used for clinical purposes since at least the 1980s. In 1978, 58 people died in the United States after following very-low-calorie liquid protein diets. Following this event, the

FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

requires since 1984 that protein VLCDs providing fewer than 400 calories a day carry a warning that they can cause serious illness and need to be followed under medical supervision. However, newer regulations require this warning only on protein products that aim to provide more than half of a person's calories and are promoted for weight loss or as a

food supplement A dietary supplement is a manufactured product intended to supplement one's diet by taking a pill, capsule, tablet, powder, or liquid. A supplement can provide nutrients either extracted from food sources or that are synthetic in order ...

. This enabled protein VLCD drinks such as Slim-Fast that provide fewer than 400 calories to avoid warnings by recommending that users "also eat one sensible meal each day". In 1991, the Federal Trade Commission charged three liquid VLCD companies, Optifast, Medifast and Ultrafast, with deceptive advertising. The case was settled after the companies agreed to stop using what the FTC alleged to be deceptive claims about the long-term results and the safety of these diets.

References

External links

Diet & VLCD - summary of studies
{{Fad diets Obesity Fad diets Fasting

Definition

Health effects

History and society

See also

References

External links