Systematic review and meta-analysis of the effect of increased vegetable and fruit consumption on body weight and energy intake.

Oliver T Mytton,Peter Scarborough,Helen Eyles,Cliona Ni Mhurchu,Kelechi Nnoaham

doi:10.1186/1471-2458-14-886

Abstract

BackgroundIncreased vegetable and fruit consumption is encouraged to promote health, including the maintenance of a healthy body weight. Population health strategies (e.g. 5-A-Day or similar campaigns and subsidies on vegetables or fruit) that emphasize increased consumption may theoretically lead to increased energy intake and weight gain.MethodsWe undertook a systematic review of trials that sought to increase vegetable and fruit consumption, in the absence of advice or specific encouragement to remove other foods from the diet, to understand the effect on body weight and energy intake. We included only randomised controlled trials. We pooled data using a random effects model for two outcomes: change in body weight and change in energy intake. Sensitivity and secondary analyses were also undertaken, including a one-study removed analysis and analysis by study sub-type to explore sources of heterogeneity.ResultsA total of eight studies, including 1026 participants, were identified for inclusion in the review. The mean study duration was 14.7 weeks (range four to 52 weeks). The mean difference in vegetable and fruit consumption between arms was 133 g (range 50 g to 456 g). The mean change in body weight was 0.68 kg (95% CI: 0.15-1.20; n = 8; I2 for heterogeneity = 83%, p = 0.01) less in the “high vegetable and fruit” intake arms than in the “low vegetable and fruit intake” arms. There was no significant difference in measured change daily energy intake between the two arms (368 kJ; 95% CI: -27 to 762, comparing high vs low; n = 6; I2 = 42%, p = 0.07).ConclusionPromoting increased fruit and vegetable consumption, in the absence of specific advice to decrease consumption of other foods, appears unlikely to lead to weight gain in the short-term and may have a role in weight maintenance or loss. Longer studies or other methods are needed to understand the long-term effects on weight maintenance and loss.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2458-14-886) contains supplementary material, which is available to authorized users.

Highlights

Increased vegetable and fruit consumption is encouraged to promote health, including the maintenance of a healthy body weight
Strategies to increase fruit and vegetable consumption are a key focus for population health [11,12,13]. Where such strategies focus on increasing vegetable and fruit consumption, without recommending substitution for other foods, there may be a risk that energy intake will increase, resulting in weight gain
Primary analysis The mean change in body weight was 0.68 kg less in the “high vegetable and fruit” intake arms than in the “low vegetable and fruit intake” arms (Figure 2a)

Summary

Introduction

Increased vegetable and fruit consumption is encouraged to promote health, including the maintenance of a healthy body weight. Population health strategies (e.g. 5-A-Day or similar campaigns and subsidies on vegetables or fruit) that emphasize increased consumption may theoretically lead to increased energy intake and weight gain. Many dietary guidelines emphasize the importance of a diet high in vegetables and fruit [5,6] Despite these guidelines, consumption of vegetables and fruit remains below recommended levels in where such strategies focus on increasing vegetable and fruit consumption, without recommending substitution for other foods, there may be a risk that energy intake will increase, resulting in weight gain. Modelling studies, based on economic data, suggest that subsidies on vegetables and fruit may result in an increase in calories purchased, as consumers can afford more food [14,15]. If all the purchased calories were consumed the net effect on health, balancing the beneficial effects (e.g. reduction in cardiovascular disease) with the adverse consequences from weight gain may be neutral or even negative [14]

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Conclusion