One of my favourite academic papers was published in 2007, by Dr Marion Franz et al. It was called “Weight-loss outcomes: a systematic review and meta-analysis of weight-loss clinical trials with a minimum 1-year follow-up” (Ref 1). I had realised many years earlier that calorie deficit dieting didn’t work long term, but this study summarised the evidence.
One of the aspects of last week’s note that generated much interest (and twitter chatter) was the weight regain for the patients in the soups and shakes intervention group. Many thanks to Amanda Atkins, who tweets as @AmandaZZ100, for her observation that “Half of those in the intervention group needed reintervention within 12 months, (some 2-3 more times)” (Ref 2).
This week’s note is going to look at the Franz et al weight loss paper – particularly for very low calorie diets – and examine the steps taken in the DiRECT study to try to counter this known regain phenomenon.
The Franz study
Franz et al performed a systematic review of 80 weight loss studies, grouped into 8 different categories, including only those trials with a 1-year follow-up. The 80 studies were published between January 1997 and September 2004. A total of 26,455 participants were enrolled in the studies. At the one-year follow-up, the attrition rate was 29% across the studies. Overall attrition was 31% at study end regardless of follow-up timing.
The eight categories were (the number of studies in each category is noted in brackets): advice alone (28); exercise alone (4); diet alone (21); meal replacements (7); diet & exercise (17); very low energy diets (11); orlistat (13) and sibutramine (7). (The 28 studies for advice alone were not counted as part of the 80 studies, as they represented the baseline).