When we consider weight-loss as part of the general population, we think fad diets, juice cleanses, working out 3 hours a day, and more. Often, these trends and fads are not backed up by evidence, and if, by chance, the blogger, news outlet, or YouTube video does include evidence, there are major flaws in the study design. Therefore, it’s incredibly important to be able to comprehend research studies aimed to discuss diets, weight-loss, and provide suggestions on how to maximize health outcomes while shedding pounds. Our bodies are incredibly complex, and this requires us to value our body machinery and scrutinize studies.
This study, published in the British Medical Journal in 2006, was a randomized control trial of four commercial weight-loss programs (1). The study indicates that all four programs (Atkins, Weight Watchers, Slim Fast, and Rosemary Conley) showed statistically significant weight-loss differences (p<0.001) compared to control group. The average weight-loss after 6 months in the intervention groups was around 5kg, compared to -0.6kg in the control group. The Atkins diet group had the greatest weight loss. From initial impressions, it seems that this study has proven the effectiveness of four commercial diet programs in weight loss, especially the Atkins diet, but there are detrimental flaws in this study that may have inflated their results. First of all, the study did not blind any of the participants to the interventions they were on. This may have resulted in participants in various programs to either try harder to lose weight compared to other groups. Also, all participants were chosen from volunteers, therefore there are inherent differences between the participants in the study compared to the general population. Second of all, the study did not make any efforts to control for co-interventions. Weight-loss can be greatly affected by how much exercise participants receive, therefore it is unknown if the weight-loss stems from their diets or from other co-interventions such as exercising. Lastly, the study fails to adjust for differences in baseline BMI, family history of obesity, and other factors that may have significantly influenced results. After such adjustments, it may be found that the interventions may be very effective for specific groups while completely ineffective for others.
When we examine epidemiology studies studying weight-loss programs, it is easy to be blind-sided by large numbers, great effects, and words such as “RCT” which may cause us to automatically assume that it is of utmost quality of evidence. However, we must critically examine all aspects of the study in order to judge it! As such, take all weight-loss programs with a grain of salt, and make sure to speak carefully with your family physician to see which program is suitable for you!