Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trial

Abstract Low-fat plant-based diets cause weight loss in clinical trials. However, many foods are highly processed, raising the question as to their effect on body weight. This secondary analysis assessed the associations between changes in processed food intake and weight loss in 244 overweight adul...

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Main Authors: Hana Kahleova, Tatiana Znayenko-Miller, Arathi Jayaraman, Giulianna Motoa, Laura Chiavaroli, Richard Holubkov, Neal D. Barnard
Format: Article
Language:English
Published: BMC 2025-03-01
Series:Nutrition & Metabolism
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Online Access:https://doi.org/10.1186/s12986-025-00912-5
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author Hana Kahleova
Tatiana Znayenko-Miller
Arathi Jayaraman
Giulianna Motoa
Laura Chiavaroli
Richard Holubkov
Neal D. Barnard
author_facet Hana Kahleova
Tatiana Znayenko-Miller
Arathi Jayaraman
Giulianna Motoa
Laura Chiavaroli
Richard Holubkov
Neal D. Barnard
author_sort Hana Kahleova
collection DOAJ
description Abstract Low-fat plant-based diets cause weight loss in clinical trials. However, many foods are highly processed, raising the question as to their effect on body weight. This secondary analysis assessed the associations between changes in processed food intake and weight loss in 244 overweight adults randomly assigned to a vegan (n = 122) or control group (n = 122) for 16 weeks. Three-day dietary records were analyzed using the NOVA system, which categorizes foods from 1 to 4, based on degree of processing. A repeated measure ANOVA, Pearson correlations, and a multivariate regression model were used for statistical analysis. The consumption of animal foods in categories 1–4 decreased in the vegan group, compared with the control group. Body weight decreased in the vegan group (treatment effect − 5.9 kg [95% CI -6.7 to -5.0]; Gxt, p < 0.001). Changes in consumption of animal foods in categories 1–4 were positively associated with changes in body weight: r = + 0.34; p < 0.001 for category 1; r = + 0.18; p = 0.008 for category 2; r = + 0.17; p = 0.01 for category 3; and r = + 0.22; p = 0.001 for category 4. In no NOVA category was the consumption of plant-based processed foods positively and significantly associated with weight gain. The top three independent predictors of weight loss were reduced intakes of processed, unprocessed or minimally processed, and ultra-processed animal foods. These findings suggest that replacing animal products with plant-based foods may be an effective weight-loss strategy, even when processed plant-based foods are included.
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spelling doaj-art-7174fd37f2ba46b9868ba6f6262a5bba2025-08-20T02:56:12ZengBMCNutrition & Metabolism1743-70752025-03-012211410.1186/s12986-025-00912-5Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trialHana Kahleova0Tatiana Znayenko-Miller1Arathi Jayaraman2Giulianna Motoa3Laura Chiavaroli4Richard Holubkov5Neal D. Barnard6Physicians Committee for Responsible MedicinePhysicians Committee for Responsible MedicinePhysicians Committee for Responsible MedicinePhysicians Committee for Responsible MedicineDepartment of Nutritional Sciences, Temerty Faculty of Medicine, University of TorontoSchool of Medicine, University of UtahPhysicians Committee for Responsible MedicineAbstract Low-fat plant-based diets cause weight loss in clinical trials. However, many foods are highly processed, raising the question as to their effect on body weight. This secondary analysis assessed the associations between changes in processed food intake and weight loss in 244 overweight adults randomly assigned to a vegan (n = 122) or control group (n = 122) for 16 weeks. Three-day dietary records were analyzed using the NOVA system, which categorizes foods from 1 to 4, based on degree of processing. A repeated measure ANOVA, Pearson correlations, and a multivariate regression model were used for statistical analysis. The consumption of animal foods in categories 1–4 decreased in the vegan group, compared with the control group. Body weight decreased in the vegan group (treatment effect − 5.9 kg [95% CI -6.7 to -5.0]; Gxt, p < 0.001). Changes in consumption of animal foods in categories 1–4 were positively associated with changes in body weight: r = + 0.34; p < 0.001 for category 1; r = + 0.18; p = 0.008 for category 2; r = + 0.17; p = 0.01 for category 3; and r = + 0.22; p = 0.001 for category 4. In no NOVA category was the consumption of plant-based processed foods positively and significantly associated with weight gain. The top three independent predictors of weight loss were reduced intakes of processed, unprocessed or minimally processed, and ultra-processed animal foods. These findings suggest that replacing animal products with plant-based foods may be an effective weight-loss strategy, even when processed plant-based foods are included.https://doi.org/10.1186/s12986-025-00912-5NOVA classificationNutritionPlant-basedProcessedVegan
spellingShingle Hana Kahleova
Tatiana Znayenko-Miller
Arathi Jayaraman
Giulianna Motoa
Laura Chiavaroli
Richard Holubkov
Neal D. Barnard
Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trial
Nutrition & Metabolism
NOVA classification
Nutrition
Plant-based
Processed
Vegan
title Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trial
title_full Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trial
title_fullStr Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trial
title_full_unstemmed Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trial
title_short Vegan diet, processed foods, and body weight: a secondary analysis of a randomized clinical trial
title_sort vegan diet processed foods and body weight a secondary analysis of a randomized clinical trial
topic NOVA classification
Nutrition
Plant-based
Processed
Vegan
url https://doi.org/10.1186/s12986-025-00912-5
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