Olive oil and body fat: a systematic review with meta-analysis

Diet composition has a great impact on body composition. Several studies have suggested a beneficial effect of adding olive oil to a calorie-restricted diet as a weight loss strategy. However, there is no clear direction regarding the effect of olive oil on body fat distribution. This systematic review with meta-analysis aims to investigate the effect of olive oil consumption (for cooking or as a supplement) on body fat distribution in adults. The present study was conducted following the recommendations of the Cochrane Handbook for Systematic Reviews of Interventions and was registered in the International Prospective Register of Systematic Reviews (PROSPERO CRD42021234652). All randomized clinical trials of parallel or crossover design found in PubMed (via MEDLINE), EMBASE, Web of Science and Scopus databases that compared the effects of olive oil with other oils on body fat distribution in adults were included. 52 articles were included. The results indicate that the consumption of olive oil does not seem to alter the distribution of body fat, despite a small indication that supplementation in capsules can increase adipose mass (Mean Difference = 0.28 kg, 95% CI [-0.27, 0.83]; between-groups difference p = 0.59) and waist circumference (mean difference = 1.74 kg, 95% CI [0.86, 1.62]; between-groups difference p p = 0.003) and time offered (slope = -0.8822, 95% CI [-1.44, -0.33], p = 0.002). In conclusion, this systematic review showed that OO ingestion in different delivery vehicles, dosages, and durations can interfere body composition. It is important to emphasize that some other aspects of the population and the intervention, that were not possible to be explored in the analysis, could confound the real effects of OO on body composition.