MedicalResearch.com Interview with: Bradley Johnston, PhD Scientist | Child Health Evaluative Sciences Hospital for Sick Children Research Institute Assistant Professor | Department of Clinical Epidemiology & Biostatistics McMaster University Toronto, Ontario, Canada Medical Research: What are the main findings of the study? Dr. Johnston:

• Our findings represent the first meta-analysis using advanced epidemiological methods to summarize popular branded diets for weight loss, trials having been investigated using randomized trial methodology.
• Among the 48 original RCTs included in our NMA, low to moderate quality evidence showed that both low-carbohydrate and low-fat diets were associated with an approximate 8 kg weight loss at 6 months when compared to no diet. Approximately 1-2 kg of this effect was lost by 12-months.
• Although statistical differences existed among several of the diet macronutrient classes, the differences were small and unlikely to be important to those seeking to lose weight.
• Similarly, our results showed that although there are statistically significant differences between some of the brand named diets, these differences are small and not likely patient important.
• In terms of potential effect modifiers, behavioural support was significant at 6-months (enhancing weight-loss by 3.23 kg) and exercise was significant at 12-months (enhancing weight loss by 2.13 kg)
• Regarding our sensitivity analyses, Differences in weight loss were not clinically important based on risk of bias, missing data, baseline weight, gender, and those with and without specific health conditions
• Overall, our findings suggest that patients may choose, among those associated with the largest weight loss, the diet that gives them the least challenges with adherence.

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