61 healthy subjects ate 2-3 packets of high-oleic peanuts every day for 12 weeks. 

The subjects should have put on 1.9 kg after 12 weeks, but they only gained half a kilogram.

The weight gain did not however result in a thicker waist or a significant increase in the body fat percentage.

“Studies have demonstrated an increase in diet induced thermogenesis and fat oxidation with MUFA possibly due to a higher stimulation of the sympathetic nervous system by MUFA than other fatty acids”

“It has been suggested that fat quality may have a stronger correlation with weight gain than fat quantity”

https://www.mdpi.com/2072-6643/7/9/5343/htm

15 subjects consumed breakfast meals containing 60% of energy as fat.

(a) olive oil rich in oleic acid, (b) sunflower oil rich in linoleic acid, or (c) flaxseed oil rich in linolenic acid

“Olive oil feeding showed a significant overall increase in energy expenditure compared with flaxseed oil (P < .0006) and a trend to increased energy expenditure compared with sunflower oil” 

https://pubmed.ncbi.nlm.nih.gov/18702944/

“Olive oil(rich in oleic acid) was able to reduce the elevated blood pressure in rats, inducing a significant and progressive sustained reduction in systolic blood pressure from as soon as 4 days after the onset of the treatment.”

“We propose that olive oil intake increases oleic acid levels in cell membranes, which causes a reduction in blood pressure by controlling G protein-mediated signaling”

https://www.pnas.org/doi/10.1073/pnas.0807500105