Cut the Waist

Cut the Waist

Illustrative photo for 'Cut the Waist'
The philosophy of Cut the Waist is to prevent obesity related ill health through education resources

Very low calorie diets

Most obese individuals can lose a substantial amount of weight in the short term with very low calorie diets. However, an insurmountable challenge for medical weight loss programmes, including very low calorie diets, has been a limitation of their ability to maintain sustained weight loss long term.

Rapid weight loss which is achieved as a result of significant caloric restriction associated with VLCDs, may be followed by a subsequent potential to accelerated weight regain. This has made very low calorie diets amongst the most controversial therapeutic strategies for the management of obesity.

A very low calorie diet involves complete substitution of all usual food intake, restricting total caloric intake to less than 800 calories daily, most commonly as a liquid formula diet.

VLCDs, by their very nature, are for short term use only. Continuous use of VLCDs should not extend beyond 12 weeks and should be undertaken under close medical supervision following careful patient selection.

Indications for very low calorie diets

Very low calorie diets are recommended for people who have a BMI ≥ 30kg/m2 and who have failed at more conservative approaches to weight management and in particular those who have a medical condition that would benefit from rapid weight loss e.g. severe obstructive sleep apnoea.

Very low calorie diets are not appropriate for certain people and for those who have the following medical conditions:

  • Infants, children, adolescents and the elderly
  • Pregnant and breastfeeding women
  • Unstable cardiac and cerebrovascular disease
  • Acute or Chronic renal failure
  • Severe Liver failure
  • Acute psychiatric disorder

Effectiveness of very low calorie diets

Long term outcome data in relation to VLCD programmes is limited. In a review of 9 randomised controlled trials (RCTs) examining sustained weight loss with VLCDs, only two trials were identified which reported weight changes over 5 years1.

Both of these trials included behaviour therapy. Complete regain of weight was observed in one of the studies after 5 years, compared with only 26% regain in the second study2,3. The precise reason for such remarkable differences in outcomes remains unclear.

The National Institute for Health (US) identified four RCT's to compare VLCDs of 400-500calories/day with low calorie diets (LCDs) of 1000-1500calories/day for a period of 6 months to 5 years. Although as expected, the VLCD produced greater initial weight loss, after 1 year the VLCDs were no more effective that the more conventional dietary treatment4.

However it is apparent that some individuals can benefit from VLCDs at least in the short to medium term. In studies using VLCDs as part of comprehensive clinical trials approximately 25-35% of subjects managed to maintain a clinically significant weight loss in the region of 10% over 2-7 years, however the majority of participants return to their pre-treatment weight5,6.

The efficacy of VLCDs in the treatment of type 2 diabetes

Weight management is the cornerstone of treatment of type 2 diabetes7 and substantial weight loss in individuals with type 2 diabetes using very low calorie diets can dramatically improve glycaemic control8. This in part may be explained by exceptional short term (<4 weeks) preferential mobilisation of visceral adipose tissue (VAT) with very low calorie diets. However, this beneficial effect on VAT is lost by 12-14 weeks9. Furthermore a trend greater initial weight loss and improved glycaemic control, followed by accelerated weight regain has been observed with VLCDs10.

Is there a future for VLCDs in the treatment of type 2 diabetes?

Very low calorie diets have been shown to reduce HbA1c, weight, insulin requirements and oral hypoglycaemic medication for patients with type 2 diabetes, sustained over a 9 month period11.

Newer agents for the treatment of type 2 diabetes include the GLP-1 agonists such as exenatide and Liraglutide which are associated with weight loss, sustained at least in the medium term. Exenatide is associated with an average weight loss 5.4kg maintained over a three year period12.

The use of these agents may therefore theoretically mitigate against the accelerated weight regain seen following VLCDs. Interestingly synergistic weight loss and diabetes resolution has also been noted with exenatide administration after laparoscopic gastric banding13.

References

1. Saris WHM. Very low calorie diets and sustained weight loss. Obes Res 2001; 9[suppl 4]: 295-301

2. Wadden TA, Strnberg JA, Letizia KA, Stunkard AJ, Foster GD. Treatment of obesity by very low calorie diet. Behaviour therapy and their combination:five year perspective. Int J Obes 1989; 13[suppl 2]: 39-46

3. Pekkarinen T, Mustajoki P. Comparison of behaviour therapy with and without very low energy diet in the treatment of obesity. A 5 year outcome. Arch Intern Med 1997; 157: 1581-5

4. US National Institutes of Health. Clinical guidelines on the identification, evaluation and treatment of overweight and obesity in adults. Am J Clin Nutr 1998; 68[4]: 899-97

5. Pekkarinen T, Takala I, Mustajoki P. Two year maintenance of weight loss after a VLED and behavioural therapy for obesity: correlation to the scores of questionnaires measuring eating behaviour. Int J Obes 1996; 20: 332-7

6. Andersen JW, Vichitbandra S, Qian W, Kryscio RJ. Long-term weight maintenance after an intensive weight loss programme. Am J Clin Nutr 1999; 18[6]: 620-7

7. Anderson JW, Kendall CWC, Jenkins DJA et al. Importance of weight management in type 2 diabetes: Review with meta-analysis of clinical studies. J Am Coll Nutr 2003; 5: 331-339

8. Capstick F, Brooks BA, Burns CM et al. Very low calorie Diets (VLCD): a useful alternative in the treatment of the obese NIDDM patient. Diabetes Research and Clinical Practice 1997; 36[2]: 105-111

9. Chaston TB, Dixon JB. Factors associate with percent change in visceral versus subcutaneous abdominal fat during weight loss: findings from a systematic review. Int J Obes 2008; 32: 691-628

10. Wing RR, Blair E, Marcus M, Epstein LH, Harvey J. Year-long weight loss treatment for obese patients with type 2 diabetes; does including an intermittent very-low-calorie diet improve outcome? Am J Med 1994: 97: 353-62

11. Dhinsa P, Scott AR, Donnelly R. Metabolic and cardiovascular effects of very low calorie diet therapy in obese patients with type 2 diabetes in secondary failure: outcomes after one year. Diabetic Medicine 2003; 20: 319-324

12. Klonoff DC, Buse JB, Nielsen LL, et al. Exenatide effects on diabetes, obesity, cardiovascular risk factors and hepatic biomarkers in patients treated for at least 3yrs. Curr Med Res Opin 2008; 24(1):275-286

13. Rothkopf MM, Bilof ML. Haverstick LP, Nusbaum MJ. Synergistic weight loss and diabetes resolution with exenatide administration after laparoscopic gastric banding. Surg Obes Relat Dis 2009; 5: 128-131