Anthony Crimarco

PURPOSE OF REVIEW: The purpose of this review is to provide an update on the available data regarding the associations of Ultra-processed food (UPF) consumption with food intake and possible underlying mechanisms relating UPF consumption to weight gain and co-morbidities. RECENT FINDINGS: In primarily observational studies, UPF consumption is consistently associated with an increased risk for weight gain among adults and children and increased risk for adiposity-related co-morbidities in adults. In a single mechanistic study, consumption of UPFs led to increased energy intake and weight gain relative to whole foods. UPFs tend to be more energy-dense than nutrient-dense, and UPF consumption is associated with increased adiposity and co-morbidity risk. These data suggest that recommendations to limit UPF consumption may be beneficial to health - though further mechanistic studies are needed.

The goal of this paper is to review the evidence related to the effect of plant-based dietary patterns on obesity and weight loss, including both observational and intervention trials. Literature from plant-based diets (PBDs) epidemiological and clinical trial research was used to inform this review. In addition, data on dietary quality, adherence, and acceptability were evaluated and are presented. Both clinical trials and observational research indicate an advantage to adoption of PBDs for preventing overweight and obesity and promoting weight loss. PBDs may also confer higher levels of diet quality than are observed with other therapeutic diet approaches, with similar levels of adherence and acceptability. Future studies should utilize health behavior theory to inform intervention development and delivery of PBDs studies and new technologies to bring interventions to scale for greater public health impact. Research examining PBDs and weight loss is also needed with more diverse populations, including older adults. Based on the available evidence, PBDs should be considered a viable option for the treatment and prevention of overweight and obesity.

Adherence is a critical factor to consider when interpreting study results from randomized clinical trials (RCTs) comparing one diet to another, but it is frequently not reported by researchers. The purpose of this secondary analysis of the Keto-Med randomized trial was to provide a detailed examination and comparison of the adherence to the two study diets (Well Formulated Ketogenic Diet (WFKD) and Mediterranean Plus (Med-Plus)) under the two conditions: all food being provided (delivered) and all food being obtained by individual participants (self-provided). Diet was assessed at six time points including baseline (×1), week 4 of each phase when participants were receiving food deliveries (×2), week 12 of each phase when participants were preparing and providing food on their own (×2), and 12 weeks after participants completed both diet phases and were free to choose their own diet pattern (×1). The adherence scores for WFKD and Med-Plus were developed specifically for this study. Average adherence to the two diet patterns was very similar during both on-study time points of the intervention. Throughout the study, a wide range of adherence was observed among participants-for both diet types and during both the delivery phase and self-provided phase. Insight from this assessment of adherence may aid other researchers when answering the important question of how to improve behavioral adherence during dietary trials. This study is registered at clinicaltrials.gov NCT03810378.