A plant-based diet in overweight individuals in a 16-week randomized clinical trial: metabolic benefits of plant protein

Hana Kahleova,Richard Holubkov,Neal D Barnard,Rebecca Fleeman,Adela Hlozkova

doi:10.1038/s41387-018-0067-4

Abstract

Background and objectivesA plant-based diet is an effective strategy in the treatment of obesity. In this 16-week randomized clinical trial, we tested the effect of a plant-based diet on body composition and insulin resistance. As a part of this trial, we investigated the role of plant protein on these outcomes.Subjects and methodsOverweight participants (n = 75) were randomized to follow a plant-based (n = 38) or a control diet (n = 37). Dual X-ray Absorptiometry assessed body composition, Homeostasis Model Assessment (HOMA-IR) assessed insulin resistance, and a linear regression model was used to test the relationship between protein intake, body composition, and insulin resistance.ResultsThe plant-based vegan diet proved to be superior to the control diet in improving body weight, fat mass, and insulin resistance markers. Only the vegan group showed significant reductions in body weight (treatment effect −6.5 [95% CI −8.9 to −4.1] kg; Gxt, p < 0.001), fat mass (treatment effect −4.3 [95% CI −5.4 to −3.2] kg; Gxt, p < 0.001), and HOMA-IR (treatment effect −1.0 [95% CI −1.2 to −0.8]; Gxt, p = 0.004). The decrease in fat mass was associated with an increased intake of plant protein and decreased intake of animal protein (r = -0.30, p = 0.011; and r = +0.39, p = 0.001, respectively). In particular, decreased % leucine intake was associated with a decrease in fat mass (r = +0.40; p < 0.001), in both unadjusted and adjusted models for changes in BMI and energy intake. In addition, decreased % histidine intake was associated with a decrease in insulin resistance (r = +0.38; p = 0.003), also independent of changes in BMI and energy intake.ConclusionsThese findings provide evidence that plant protein, as a part of a plant-based diet, and the resulting limitation of leucine and histidine intake are associated with improvements in body composition and reductions in both body weight and insulin resistance.

Highlights

Suboptimal nutrition is a major cause of obesity, chronic disease, and premature death across the nation and worldwide[1,2]
These findings provide evidence that plant protein, as a part of a plant-based diet, and the resulting limitation of leucine and histidine intake are associated with improvements in body composition and reductions in both body weight and insulin resistance
Main findings This study demonstrated that the quality and quantity of dietary protein from a plant-based vegan diet are associated with improvements in body composition, body weight, and insulin resistance in overweight individuals

Summary

Introduction

Suboptimal nutrition is a major cause of obesity, chronic disease, and premature death across the nation and worldwide[1,2]. Certain dietary habits, such as high intakes of sodium and processed meat products and low intakes of fruits and vegetables, are associated with 45.5% of cardio-metabolic deaths in the United States[3]. While adequate in macro and micronutrients[6], people sometimes question the ability to reach protein requirements on a plant-based vegan diet. A diet based entirely on plants provides all essential amino acids and an adequate quantity of overall protein, even without the use of special food combinations[6]. As a part of this trial, we investigated the role of plant protein on these outcomes

Results

Discussion

Conclusion