Impact of Dietary Ultra-Processed Food Restriction on Withdrawal Symptoms in Individuals with Obesity Undergoing a Weight Loss Diet: Secondary Analysis of a Randomized Clinical Trial.

BACKGROUND & AIMS: Ultra-processed foods (UPF) are typically hyperpalatable and prone to induce cravings and loss-of-control eating, particularly among individuals with obesity undergoing weight loss. This study evaluated whether restricting UPF intake leads to withdrawal symptoms in individuals with obesity and examined its associations with anxiety and food addiction (FA). METHODS: Secondary analysis of a randomized clinical trial in which individuals were assigned to either a generic energy restriction (ER-G) or an energy restriction combined with UPF restriction (ER-UPF). Dietary intake, generalized anxiety disorder, and FA were assessed at baseline. Withdrawal symptoms were measured using the Highly Processed Food Withdrawal Scale (ProWS) at 1, 3, 5, and 15 days after the start of the intervention, alongside UPF intake assessed using the NOVA-UPF score. RESULTS: A total of 107 participants were randomized (51 to ER-G and 56 to ER-UPF). The ER-UPF group showed a significant reduction in UPF intake over time (group × time p < 0.001). In contrast, ProWS scores after intervention did not significantly differ between groups, with scores estimated to be 4.34 points higher in ER-UPF (95% CI -1.97 to 10.6; p = 0.175). Exploratory analysis showed that baseline anxiety was significantly associated with ProWS scores (p < 0.001), with a borderline anxiety × group × time interaction (p = 0.05), whereas FA was not associated with ProWS scores across follow-up, although only 16% of the individuals had FA. CONCLUSION: UPF restriction did not result in significantly higher post-intervention ProWS scores compared with generic energy restriction in free-living individuals with obesity and anxiety appears to play a role on such symptoms. TRIAL REGISTRATION: ReBEC RBR-3q9vgk9.