Seed oils make you FAT

I see a lot of posts about how different ingredients we use every day contribute to obesity for one reason or another. Some of the frequent targets are seed oils, like canola or vegetable oil, and margarine. People recommend olive oil, but it’s low smoke point makes it far from ideal for many cooking applications. I could switch to “real” butter, but I am mildly lactose intolerant, and I prefer something easily spreadable for making toast.

What are the substitutes I SHOULD be using in my cooking that can accomplish the same jobs as these allegedly unhealthy processed ingredients?

I ask this as someone who has been overweight my entire life and cooks the majority of my meals.