Scoring adherence to voluntary restriction diets (SAVoReD) in the ADAPT study

Voluntary adoption of popular food-group-restricting diets like Paleo and plant-based diets (PBDs) are often health-motivated. However, unlike the theoretical design of these diets, different levels of dietary adherence may result in different diet quality and bodyweight in real-world settings-a limitation to the efficacy of dietary interventions. Scoring Adherence to Voluntary Restriction Diets (SAVoReD) is a metric to quantify and compare adherence across food-group-restricting diets. We applied the score to four diets, whole food plant-based (WFPB), vegan, vegetarian, and Paleo to examine associations between adherence and diet quality (Healthy Eating Index; HEI), body mass index (BMI), and diet duration. We also explored the independent associations of adherence and duration with BMI. Higher adherence to WFPB and vegan diets was significantly associated with lower BMI, but no association was observed for vegetarian or Paleo diet followers. For vegan and WFPB, greater adherence was associated with lower BMI among those following their diet ≥2 years compared to <2 years. Adherence was lowest in the diet with the most restrictions (WFPB); however, the stricter fully plant-based diets (WFPB and vegan) had the healthiest HEI scores and BMIs and many long-term followers. Our results suggest that identification with fully plant-based diets is associated with better diet quality and BMI. Vegan, vegetarian, and WFPB diets are often grouped as 'plant-based diets' despite the differing diet compositions, diet quality, adherence, and BMI of followers-thus, grouping them may distort findings. Individuals may benefit from encouragement following a fully plant-based diet, even without perfect adherence.