Because I am not eating much grease/fat during this diet, so I will get that from the oil. Anyways, I got an answer from my sister! Rapeseed oil doesn't taste like anything, so if I put a bit of salt (which I need to eat a lot too) into it, I can eat it with my food!
Also, if you have problems with your posture and/or shoulders, use kettlebell. It looks stupid (imo), but it's really effective. It has already helped me! (yaay)