Use of plant-based dietary approaches for weight loss has public health appeal. There was no restriction on energy intake recommended to any of the groups in the study. Participants were free to eat until they were satisfied. Because traditional weight loss dietary approaches require dietary self-monitoring, which often is viewed as burdensome [26], time consuming, and tedious by participants [27], dietary approaches that do not require self-monitoring may be appealing for individuals who are resistant to dietary self-tracking. Additionally, rates of dietary adherence did not differ by group, demonstrating that no single diet emerged as easier for participants to follow.
In studies using traditional reduced-energy weight loss diets, adherence to and frequency of self-monitoring are highly corre- lated with weight loss [28]. Whereas adherence is important with traditional dietary approaches, the present study examines the effect of recommending different plant-based diets to free-living individuals and suggests that adherence to plant-based diets, such as vegan and vegetarian diets may not need to be complete. In a randomized trial examining 2-y weight loss comparing a vegan diet to the National Cholesterol Education Program Step 2 diet (a standard low-fat diet), dietary adherence at 2 y was marginal (60% adherent vegan, 55% adherent in Step 2) and not significantly different between the two diet groups, but the vegan group had a significantly greater weight loss than the Step 2 diet group [3]. Although adherence rates were low in all groups, the vegan group had more dietary adherence criteria to meet to count as adherent than the other groups. The 2 d of dietary recalls at each time point had to be free of eggs or foods containing eggs, dairy products or foods containing dairy products, meat, poultry, and fish to be considered adherent. For example, a participant in the vegan group could have had egg whites in a recipe, which wouldn’t impact overall macronutrient intake to any large degree, but would still be considered nonadherent to the diet. Participants in the pesco-veg group, for example, could have had eggs or foods containing eggs, dairy products or foods containing dairy products, and fish on their dietary recalls and still be considered adherent