Effectiveness of a minimally processed food-based nutritional counselling intervention on weight gain in overweight pregnant women: a randomized controlled trial

PURPOSE: This study aimed at evaluating the effectiveness of a nutritional counselling intervention based on encouraging the consumption of unprocessed and minimally processed foods, rather than ultra-processed products, and the practice of physical activities to prevent excessive gestational weight gain in overweight pregnant women. METHODS: This was a two-armed, parallel, randomized controlled trial conducted in primary health units of a Brazilian municipality from 2018 to 2021. Overweight, adult pregnant women (n = 350) were randomly assigned to control (CG) or intervention groups (IG). The intervention consisted of three individualized nutritional counselling sessions based on encouraging the consumption of unprocessed and minimally processed foods rather than ultra-processed products, following the NOVA food classification system, and the practice of physical activities. The primary outcome was the proportion of women whose weekly gestational weight gain (GWG) exceeded the Institute of Medicine guidelines. Adjusted logistic regression models were employed. RESULTS: Complete data on weight gain were available for 121 women of the IG and 139 of the CG. In modified intention-to-treat analysis, there was a lower chance of the IG women having excessive GWG [OR 0.56 (95% CI 0.32, 0.98), p = .04], when compared to the CG. No between-group differences were observed for the other maternal outcomes investigated. CONCLUSION: The present study was unprecedented in demonstrating that nutritional counselling based on the NOVA food classification system, together with encouraging the practice of physical activity, is effective in preventing excessive weight gain in overweight pregnant women. TRIAL REGISTRATION: Registered on July 30th 2018 at Brazilian Registry of Clinical Trials (RBR-2w9bhc). SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s00394-022-02995-9.