Very low energy diets in the treatment of obesity

Abstract

Very low energy diets (VLEDs) are defined as diets which contain energy levels of less than 3.4 MJ (800 kcal) per day and contain daily allowances of all essential nutritional requirements. These diets have been in clinical use for more than 20 years. They are used as the only source of nutrition for 8-16 weeks, which usually achieves a weight loss of 1.5-2.5 kg per week. Before using this type of diet a medical investigation is necessary to evaluate contraindications and to check medication use during the diet. To facilitate maintenance, cognitive behavioural counselling should always be included in a weight reduction programme using a very low energy diet. VLEDs have no serious harmful effects and can safely be used in patients with various chronic diseases. Programmes using VLEDs produce better short-term weight loss than programmes without the diet. However, in randomized controlled trials VLED-based programmes have not achieved significantly better long-term maintenance than conventional programmes. VLEDs are used when rapid weight loss is necessary because of an obesity-related disease. In other patients with obesity it is an alternative to other conservative approaches for treatment of obesity. In type 2 diabetes it may improve long-term glucose metabolism better than conventional weight reducing diets. Some studies suggest that after a VLED-based programme long-term maintenance is better among men than women. This possible gender difference is an important topic for further research.

Program compliance, weight loss and health profile changes in WHO obesity classes after very low energy dietary intervention

“…These health profile changes can also offer an additional point of reference for measuring success in weight management programs. These findings mirror those of other studies that have used similar VLED weight control programs over 3-6 month periods, but with separate groups of male and female obese participants [17,18,22,24,29,30]. The magnitude of weight loss (~20-25kg+) and reduction in BMI (by 7-9 kg/m 2 ) found here with high compliance is similar to changes reported previously in male and female group data [18,29,30].…”

“…These findings mirror those of other studies that have used similar VLED weight control programs over 3-6 month periods, but with separate groups of male and female obese participants [17,18,22,24,29,30]. The magnitude of weight loss (~20-25kg+) and reduction in BMI (by 7-9 kg/m 2 ) found here with high compliance is similar to changes reported previously in male and female group data [18,29,30]. With the substantial weight loss achieved with high compliance here, it is noted that Class III obese persons reverted to Class II (45.4 to 36.0 kg/m 2 ) and Class II obese persons reverted to "overweight" (37.1 to 29.8 kg/m 2 ), as did Class I (33.0 to 26.6 kg/m 2 ).…”

“…Unfortunately, no follow up on the participants used here was possible, but there is no evidence that VLED programs lead to worse long term outcomes than other weight loss treatments [29,32]. Another potential limitation is that the participants were all drawn from one clinic and could only be assessed over a 6 month period.…”

Health-related quality of life in obese outpatients losing weight with very-low-energy diet and behaviour modification—a 2-y follow-up study

“…33 Initially, marked weight loss may be significant in improving longterm weight loss maintenance. 34 The aim of this study was to examine HRQL in obese hospital outpatients before and after treatment with VLED and behaviour modification, and to examine whether beneficial changes in HRQL can be maintained up to 2 y.…”

Health-related quality of life in WHO Class II–III obese men losing weight with very-low-energy diet and behaviour modification: a randomised clinical trial

“…Combining a very-low-energy diet (VLED) with behaviour modification produces rapid and marked initial weight loss, 27 which may improve long-term maintenance. 28 The aim of this trial was to study the short-term and maintained effects of marked weight loss on HRQOL in a clinically representative population of WHO Class II -III obese men.…”