The calories in any food or oil can cause weight gain if excess calories are consumed. IF you take in more calories than you burn in a day, the excess calories are stored as fat. If you store 3500 excess calories as fat, it will reflect 1 pound of weight gain. 3500 calories = 1 pound of bodyfat.
Like what b2reflect is saying about weightloss associated with coconut oil, I think it has to do with metabolism where a person's hormones are not in proper balance and somehow the coconut oil helps to balance the hormones and that is how folks are testifying to weightloss. Most of these people are probably way overweight too. I'm at the right weight for my heigth, I haven't noticed any weightloss. I've been using the oil for a month.