• Turns out telling people to “eat more fruits and vegetables” doesn’t work

    From the American Journal of Clinical Nutrition, “Increased fruit and vegetable intake has no discernible effect on weight loss: a systematic review and meta-analysis“:

    Background: A common dietary recommendation for weight loss, especially in lay public outlets, is to eat more fruit and vegetables (F/Vs). Without a compensatory reduction in total energy intake, significant weight loss would be unlikely.

    Objective: We aimed to synthesize the best available evidence on the effectiveness of the general recommendation to eat more F/Vs for weight loss or the prevention of weight gain.

    Design: We searched multiple databases for human randomized controlled trials that evaluated the effect of increased F/V intake on body weight. Inclusion criteria were as follows: ≥ 15 subjects/ treatment arm, ≥8-wk intervention, a stated primary or secondary outcome of body weight, the stated goal of the intervention was weight or fat loss or the prevention of weight or fat gain, and food intake provided or prescribed was of a variety of F/Vs that remained minimally processed.

    How many times have you been told to “eat more fruits and vegetables”? So many, I bet, that it’s just become accepted folk wisdom to do so. Well, these researchers went about looking for all the studies that examined what happened to people when they did so.

    They found two studies that met all of their inclusion criteria (see the design above), and 5 others that met all criteria but one. The main outcome of interest was an effect size of weight change. When they looked at the studies that met all criteria, they found no significant effect of increased fruits and vegetables. When the looked at the 7 studies that met at least all the criteria but one, they still found no significant effect of increased fruits and vegetables.

    These studies included both “recommendations” to eat more fruits and vegetables, and the actual provision of more fruits and vegetables to get this done. No difference. So why do we keep repeating and trying this? It doesn’t work. More instructions and changes are needed.

    In case you can’t tell from my many, many, many posts on obesity and diet, I’m getting despondent. See my post later today for some ideas on what I’d like to do about that.

    @aaronecarroll

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