Whole grain and body weight changes in apparently healthy adults: a systematic review and meta-analysis of randomized controlled studies.

BACKGROUND

Whole grains have received increased attention for their potential role in weight regulation. A high intake has been associated with smaller weight gain in prospective cohort studies, whereas the evidence from randomized controlled studies has been less consistent.

OBJECTIVE

We assessed the effects of whole-grain compared with non-whole-grain foods on changes in body weight, percentage of body fat, and waist circumference by using a meta-analytic approach.

DESIGN

We conducted a systematic literature search in selected databases. Studies were included in the review if they were randomized controlled studies of whole-grain compared with a non-whole-grain control in adults. A total of 2516 articles were screened for eligibility, and relevant data were extracted from 26 studies. Weighted mean differences were calculated, and a metaregression analysis was performed by using the whole-grain dose (g/d).

RESULTS

Data from 2060 participants were included. Whole-grain intake did not show any effect on body weight (weighted difference: 0.06 kg; 95% CI: -0.09, 0.20 kg; P = 0.45), but a small effect on the percentage of body fat was seen (weighted difference: -0.48%; 95% CI: -0.95%, -0.01%; P = 0.04) compared with that for a control. An examination of the impact of daily whole-grain intake could predict differences between groups, but there was no significant association (β = -0.0013 kg × g/d; 95% CI: -0.011, 0.009 kg × g/d).

CONCLUSIONS

Whole-grain consumption does not decrease body weight compared with control consumption, but a small beneficial effect on body fat may be present. The relatively short duration of intervention studies (≤16 wk) may explain the lack of difference in body weight and fat. Discrepancies between studies may be caused by differences in study design.