Very-low-calorie diet

Definition

Very-low-calorie diets (VLCDs) are diets of 800 kcal or less energy intake per day, whereas low-calorie diets are between 1000 and 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 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 4 kg 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 10 kg 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 diets, and the maintained long-term weight loss is similar or greater. VLCDs were shown to reduce lean body mass. 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 lean body mass 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 gallstones 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 (depending on the fiber 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 1.5 –. However, the total lack of carbohydrates avoids protein sparing and thus produce a loss of lean muscle mass, as well as other adverse side effects such as increased risks of gout, and electrolyte imbalances, 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 nutritional status.

Unmonitored VLCDs with insufficient macronutrient and mineral intake have the potential to cause an electrolyte imbalance and sudden death via ventricular tachycardia either by starvation or upon refeeding.

History and society

The earliest data on VLCDs come from the aftermath of World War II, 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, 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 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. 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

References

1. (April 2001). "Cardiovascular complications of weight reduction diets.". The American Journal of the Medical Sciences.
2. (27 April 2018). "How to diet". NHS.
3. "Take the test: Is an 800-calorie diet right for me?". BBC Food.
4. (28 November 2018). "Are crash diets ever a good idea for weight loss?".
5. (November 2018). "Pros & cons of some popular extreme weight-loss diets.". The Indian Journal of Medical Research.
6. (15 September 2009). "Crash dieting: Desperate measures".
7. (2018-02-02). "Crash diets can cause transient deterioration in heart function".
8. (September 2016). "Guidelines for Perioperative Care in Bariatric Surgery: Enhanced Recovery After Surgery (ERAS) Society Recommendations.". World Journal of Surgery.
9. (February 2018). "Effects of very low calorie diets on liver size and weight loss in the preoperative period of bariatric surgery: a systematic review.". Surgery for Obesity and Related Diseases.
10. (1981). "The historical development, efficacy and safety of very-low-calorie diets". International Journal of Obesity.
11. (November 2014). "Obesity: identification, assessment and management of overweight and obesity in children, young people and adults.". NICE.
12. (2017). "2015–2020 Dietary Guidelines for Americans - health.gov". Skyhorse Publishing Inc..
13. (24 June 2014). "2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society.". Circulation.
14. (December 1979). "Sudden, unexpected death in avid dieters using the liquid-protein-modified-fast diet. Observations in 17 patients and the role of the prolonged QT interval". Circulation.
15. (April 1981). "Sudden death associated with very low calorie weight reduction regimens". The American Journal of Clinical Nutrition.
16. Strychar I. (January 2006). "Diet in the management of weight loss". CMAJ.
17. (May 2017). "Is There an Optimal Diet for Weight Management and Metabolic Health?". Gastroenterology.
18. (March 2016). "Clinical effectiveness of very-low-energy diets in the management of weight loss: a systematic review and meta-analysis of randomized controlled trials". Obesity Reviews.
19. (September 2018). "Doctor Referral of Overweight People to Low Energy total diet replacement Treatment (DROPLET): pragmatic randomised controlled trial". BMJ.
20. (April 2015). "Efficacy of commercial weight-loss programs: an updated systematic review". Annals of Internal Medicine.
21. (25 April 2018). "Effects of Different Weight Loss Approaches on CVD Risk.". Current Atherosclerosis Reports.
22. Anderson JW, Konz EC, Frederich RC, Wood CL. (1 November 2001). "Long-term weight-loss maintenance: A meta-analysis of US studies". Am. J. Clin. Nutr..
23. (September 2016). "Alternate-day versus daily energy restriction diets: which is more effective for weight loss? A systematic review and meta-analysis.". Obesity Science & Practice.
24. (March 2014). "Combination of very low energy diets and pharmacotherapy in the treatment of obesity: meta-analysis of published data.". Diabetes/Metabolism Research and Reviews.
25. (February 2001). "Very low energy diets in the treatment of obesity.". Obesity Reviews.
26. (July 1992). "Liver and gallbladder disease before and after very-low-calorie diets". The American Journal of Clinical Nutrition.
27. (1989). "VLCD compliance and lean body mass". International Journal of Obesity.
28. (February 1990). "Dietary fibre added to very low calorie diet reduces hunger and alleviates constipation". International Journal of Obesity.
29. (October 2017). "Extended calorie restriction suppresses overall and specific food cravings: a systematic review and a meta-analysis.". Obesity Reviews.
30. (1975). "Obesity: Its Pathogenesis And Management". Springer Netherlands.
31. (May 2015). "Fasting for weight loss: an effective strategy or latest dieting trend?". International Journal of Obesity.
32. (25 November 2014). "Encyclopedia of diet fads: understanding science and society". Greenwood.