Very Low Calorie Diet
Encyclopedia
Very low calorie diet is a diet
with very or extremely low daily food energy
consumption. It is defined as a diet of 800 kilocalories (3,347,200 J) per day or less. VLCDs are formulated, nutrition
ally complete, liquid meal
s containing 800 kilocalories or less per day. VLCDs also contain the recommended daily requirements for vitamin
s, minerals
, trace element
s, fatty acid
s and protein
. Carbohydrate
may be entirely absent, or substituted for a portion of the protein; this choice has important metabolic effects. The VLCD products are usually a powder which is mixed with water or another low-food-energy liquid. The VLCD is prescribed on a case to case basis for rapid weight loss (about 1.5 to 2.5 kilograms or 3 to 5 pounds per week) in patients with Body Mass Index
of 30 and above. The health care provider can recommend the diet to a patient with BMI between 27 and 30 if the medical complications the patient has due to overweight present serious health risk.
control and promoting substantial weight loss
in obese patients with Type 2 diabetes
. Moreover, a VLCD increases insulin
sensitivity and reduces the substrate for gluconeogenesis
. Thus VLCD treatment may improve glycaemic control more than calorie restriction
alone. A VLCD is typically undertaken by an obese patient who wishes to lose a lot of weight quickly, as the risk to health that obesity presents is considered much greater than any risks of the diet itself, so long as it is undertaken with medical supervision.
s develop. However, these gallstones may be small enough to not cause discomfort, and often disappear when a normal eating pattern is resumed. Gallstone formation is facilitated by the more concentrated bile
fluid and reduced flow as a result of a VLCD.
Another potential side effect is constipation
(depending on the fiber
content of the diet). Most VLCDs recommend drinking 5 litres of water a day to nullify this effect.
Diet (nutrition)
In nutrition, diet is the sum of food consumed by a person or other organism. Dietary habits are the habitual decisions an individual or culture makes when choosing what foods to eat. With the word diet, it is often implied the use of specific intake of nutrition for health or weight-management...
with very or extremely low daily food energy
Food energy
Food energy is the amount of energy obtained from food that is available through cellular respiration.Food energy is expressed in food calories or kilojoules...
consumption. It is defined as a diet of 800 kilocalories (3,347,200 J) per day or less. VLCDs are formulated, nutrition
Nutrition
Nutrition is the provision, to cells and organisms, of the materials necessary to support life. Many common health problems can be prevented or alleviated with a healthy diet....
ally complete, liquid meal
Meal
A meal is an instance of eating, specifically one that takes place at a specific time and includes specific, prepared food.Meals occur primarily at homes, restaurants, and cafeterias, but may occur anywhere. Regular meals occur on a daily basis, typically several times a day...
s containing 800 kilocalories or less per day. VLCDs also contain the recommended daily requirements for vitamin
Vitamin
A vitamin is an organic compound required as a nutrient in tiny amounts by an organism. In other words, an organic chemical compound is called a vitamin when it cannot be synthesized in sufficient quantities by an organism, and must be obtained from the diet. Thus, the term is conditional both on...
s, minerals
Dietary mineral
Dietary minerals are the chemical elements required by living organisms, other than the four elements carbon, hydrogen, nitrogen, and oxygen present in common organic molecules. Examples of mineral elements include calcium, magnesium, potassium, sodium, zinc, and iodine...
, trace element
Trace element
In analytical chemistry, a trace element is an element in a sample that has an average concentration of less than 100 parts per million measured in atomic count, or less than 100 micrograms per gram....
s, fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
s and protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
. Carbohydrate
Carbohydrate
A carbohydrate is an organic compound with the empirical formula ; that is, consists only of carbon, hydrogen, and oxygen, with a hydrogen:oxygen atom ratio of 2:1 . However, there are exceptions to this. One common example would be deoxyribose, a component of DNA, which has the empirical...
may be entirely absent, or substituted for a portion of the protein; this choice has important metabolic effects. The VLCD products are usually a powder which is mixed with water or another low-food-energy liquid. The VLCD is prescribed on a case to case basis for rapid weight loss (about 1.5 to 2.5 kilograms or 3 to 5 pounds per week) in patients with Body Mass Index
Body mass index
The body mass index , or Quetelet index, is a heuristic proxy for human body fat based on an individual's weight and height. BMI does not actually measure the percentage of body fat. It was invented between 1830 and 1850 by the Belgian polymath Adolphe Quetelet during the course of developing...
of 30 and above. The health care provider can recommend the diet to a patient with BMI between 27 and 30 if the medical complications the patient has due to overweight present serious health risk.
Health benefits
A 1997 study concludes that the short-term use of a VLCD is very effective in rapidly improving glycaemicGlycemia
Glycemia means the presence, or the level, of glucose in one's blood. Related words include:* Hyperglycemia, an unusually high concentration of sugar in the blood* Hypoglycemia, an unusually low concentration of sugar in the blood...
control and promoting substantial weight loss
Weight loss
Weight loss, in the context of medicine, health or physical fitness, is a reduction of the total body mass, due to a mean loss of fluid, body fat or adipose tissue and/or lean mass, namely bone mineral deposits, muscle, tendon and other connective tissue...
in obese patients with Type 2 diabetes
Diabetes mellitus type 2
Diabetes mellitus type 2formerly non-insulin-dependent diabetes mellitus or adult-onset diabetesis a metabolic disorder that is characterized by high blood glucose in the context of insulin resistance and relative insulin deficiency. Diabetes is often initially managed by increasing exercise and...
. Moreover, a VLCD increases insulin
Insulin
Insulin is a hormone central to regulating carbohydrate and fat metabolism in the body. Insulin causes cells in the liver, muscle, and fat tissue to take up glucose from the blood, storing it as glycogen in the liver and muscle....
sensitivity and reduces the substrate for gluconeogenesis
Gluconeogenesis
Gluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
. Thus VLCD treatment may improve glycaemic control more than calorie restriction
Calorie restriction
Caloric restriction , or calorie restriction, is a dietary regimen that restricts calorie intake, where the baseline for the restriction varies, usually being the previous, unrestricted, intake of the subjects...
alone. A VLCD is typically undertaken by an obese patient who wishes to lose a lot of weight quickly, as the risk to health that obesity presents is considered much greater than any risks of the diet itself, so long as it is undertaken with medical supervision.
Adverse effects
Studies have shown that in about one in four individuals following a VLCD for a few months, gallstoneGallstone
A gallstone is a crystalline concretion formed within the gallbladder by accretion of bile components. These calculi are formed in the gallbladder, but may pass distally into other parts of the biliary tract such as the cystic duct, common bile duct, pancreatic duct, or the ampulla of...
s develop. However, these gallstones may be small enough to not cause discomfort, and often disappear when a normal eating pattern is resumed. Gallstone formation is facilitated by the more concentrated bile
Bile
Bile or gall is a bitter-tasting, dark green to yellowish brown fluid, produced by the liver of most vertebrates, that aids the process of digestion of lipids in the small intestine. In many species, bile is stored in the gallbladder and upon eating is discharged into the duodenum...
fluid and reduced flow as a result of a VLCD.
Another potential side effect is constipation
Constipation
Constipation refers to bowel movements that are infrequent or hard to pass. Constipation is a common cause of painful defecation...
(depending on the fiber
Dietary fiber
Dietary fiber, dietary fibre, or sometimes roughage is the indigestible portion of plant foods having two main components:* soluble fiber that is readily fermented in the colon into gases and physiologically active byproducts, and* insoluble fiber that is metabolically inert, absorbing water as it...
content of the diet). Most VLCDs recommend drinking 5 litres of water a day to nullify this effect.