Where Do Medically Supervised Low-Calorie Diets Fit In?

Low calorie diets, usually consisting of a variable period of formula diets, followed by variable periods and intensities of follow-up, have been around for decades.

While there is little doubt that such diets can help patients lose large amounts of weight in a short period of time (rivalling or even exceeding what is seen with bariatric surgery), the large-scale feasibility and durability of this intervention remains controversial.

A study that speaks both to the feasibility and efficacy, at least over a 1-3 year period, is now published by Stephan Bischoff (University of Hohenheim, Stuttgart, Germany) and colleagues in the latest issue of the International Journal of Obesity.

In this paper, Bischoff and colleagues describe the outcomes of a prospective longitudinal observational study of Prospective multicenter observational study in over 8,000 obese individuals (mean BMI 43.0) undergoing a medically supervised 52-week treatment in 37 centres across Germany (a small subset of patients was followed for up to 3 years).

The program consisted of 5 treatment phases:

Phase 1: a 1-weekintroduction time to check inclusion and exclusion criteria;

Phase 2: a 12-week-period of low-calorie diet (LCD; 800 kcal per day) during which participants consume formula diet exclusively (daily consumption of five packets of 160 kcal meal replacement products dissolved in 300 ml water each; Optifast 800 formula, Nestle´ Inc.), accompanied by 12 medical examinations, 12 exercise units, two behavior therapy lessons and two nutrition counselling sessions;

Phase 3: a 6-week-refeeding phase, during which solid food is reintroduced and formula diet is stepwise replaced by normal diet without change of total energy intake, accompanied by six medical examinations, six exercise units, two behaviour therapy lessons and six nutrition counselling session;

Phase 4: a 7-week stabilization phase in which energy intake is stepwise, enhanced to an individual level that allows weight stabilization, accompanied by three medical examinations, four exercise units, four behavior therapy lessons and three nutrition counselling session;

Phase 5: a 26-week-maintenance phase in which nutritional education and behavior modification is intensified to learn coping strategies and to achieve longterm weight control, accompanied by six medical examinations, 13 exercise units, 22 behavior therapy lessons and five nutrition counselling session.

Of the over 8,000 patients, who started the program, over 3,000 (or about 42%) discontinued the treatment.

Given this rather high discontinuation rate, the stated reasons for discontinuation are of interest: personal reasons (6.9%), no further appearance (6.5%), job related reasons (5.1%), disease/medical reasons (3.6%), financial reasons (3.4%), feeling of sufficient success (2.2%), familiar reasons (2.0%), mental/psychological reasons (1.5%), exclusion by the program team (1.4%), weight regain (1.0%), product dissatisfaction (0.6%) or pregnancy (0.4%). In about 1/6 of cases, the reason was unknown (7.2%).

Nevertheless, even with this relatively large number of discontinuations, the ‘intention-to-treat’ (ITT) results were impressive: At week 52, average weight loss was around 15 Kg in women and about 19 Kg in men. The prevalence of metabolic syndrome decreased by 50%. There were also remarkable improvements in quality of life and several other measures of health and functioning.

Overall the treatment was well tolerated with the most common ‘side effects’ being constipation, hair loss, and gall bladder problems (all known to be complication of significant weight loss).

So where do LCD interventions fit in?

The authors themselves are careful in pointing out that data on the long-term efficacy of such interventions are sketchy. Although there have been some reports that even several years after such an intervention, the average weight loss is still about 5% below the initial weight of the group, individuals weight trajectories appear highly variable. While some patients manage to keep much of the weight off, others will regain the weight within months of completing the intervention.

This should not come as a surprise given the chronicity of obesity – when treatment stops the weight comes back!

This then raises the issue of why one would even consider a time-limited obesity intervention program – why 52 weeks? Why not 104 weeks or 208 weeks or 416 weeks or in fact every week thereafter forever?

This is where things get murky. While I have no doubt that there are indeed a substantial number of individuals for whom an LCD approach works and may well lead to long-term weight loss maintenance (even with little long-term support or follow-up), I would assume that the vast majority of patients will require ongoing and lifelong continuing support – something seldom offered by such program and something that many patients are unlikely to comply with if too onerous or expensive.

This does not mean that there is not an important role for LCDs in bariatric practice. LCDs can certainly be considered a viable option for patients unwilling or unable to undergo bariatric surgery. They certainly also have their place in helping patients achieve rapid and medically safe weight loss in situations where such drastic weight loss is indicated (e.g. preparation for surgery or a diagnostic procedure).

Will such interventions prove to be cost effective? I believe the jury is out on this but this question clearly begs an answer.

As so often, the interpretation of the present findings will differ: while the ‘glass-half-empty’ folks will point to the high number of patients, who discontinue or rapidly regain the weight they lose, the ‘glass-half-full’ folks will highlight the fact that 2 in 3 patients of the 50% who do complete the program may still be well below their initial weight 3 years later.

Given our rather limited range of successful obesity treatment strategies and the fact that surgery may not be for everyone, I do strongly feel that LCDs should be part of the general armamentum of bariatric care and are probably underused in patients, who could well benefit from this approach and may well be overused in patients, who will probably not.

Edmonton, Alberta

ResearchBlogging.orgBischoff SC, Damms-Machado A, Betz C, Herpertz S, Legenbauer T, Löw T, Wechsler JG, Bischoff G, Austel A, & Ellrott T (2011). Multicenter evaluation of an interdisciplinary 52-week weight loss program for obesity with regard to body weight, comorbidities and quality of life-a prospective study. International journal of obesity (2005) PMID: 21673653