Effect of unprocessed red meat on obesity and related factors: A systematic review and meta-analysis.

Objective: The objective of this study was to conduct a systematic review and meta-analysis of intervention trials that have determined the effect of unprocessed red meat (URM) intake on obesity-related outcomes.

Methods: The populations, interventions, controls, and outcomes (PICO) framework was used to create questions to search seven databases from July 29, 2020, to August 21, 2020. Two reviewers independently screened 5630 references. English-language intervention trials in adults testing the effect of URM on obesity-related outcomes were included. Twenty-four studies met selection criteria. A random-effects model was developed to calculate pooled effect sizes. The DerSimonian-Laird estimator was used to estimate the variance of the true effect sizes. An interactive dashboard was published to provide transparent analysis and data presentation.

Results: We found no significant effect of URM for BMI, body weight, or percent body fat based on unfiltered pooled effect sizes. Filtered pooled effect size analysis showed a slight adverse effect of URM for total cholesterol and low-density lipoprotein cholesterol.

Conclusions: Studies did not show an effect of URM on weight gain, obesity, or related metabolic conditions. This may help clinicians when considering the use of URM for patients. Longer studies may be needed for observing obesity development in case the effect of URM on weight gain is small and needs a much longer time to express.