Does extra-virgin olive oil cause fat loss? Probably yes.

https://www.ncbi.nlm.nih.gov/pubmed/30461730

In this meta analysis of non-majorly flawed randomised controlled trials (RCTs): Adding 25 to 50 mL of olive oil to the diet reduced total weight by 0.5 to 1.7 kg more than placebo, in people age 20 to over 65 and of BMI 22 to 35 range (meta-analysis of 6 low risk of bias RCTs), if taken for at least 3 months. The I^2 in this group was an acceptable 43.5% (in other words, the variation between the studies was not significantly high).