…that olive leaf extract has been shown to help patients with weight loss? 

The mechanism of action appears to be through the slowing of digestion of starches into simple sugars, slowing of the absorption of simple sugars from the intestines and through increased uptake of blood glucose into muscle and other tissues from the blood to be used as an energy source.  Patients with diabetes or insulin resistance on prescription medication should monitor their blood sugars closely while taking olive leaf extract.