I also switched to a canola-based margarine, but recently I couldn't find any and had gone back to regular margarine Have you considered trying butter instead of margarine? It tastes a lot better, and is better for you. As long as you don't consume it in a high-carbohydrate diet, the saturated fat from butter is a healthy part of a balanced diet (a lot better than the hydrogenated oils used in margarine) and you get healthy amounts of many nutrients (vitamin A, vitamin E, selenium, etc.) as a nice bonus in addition to the better flavor.
Fat is actually good for you. When people go on low-fat diets and return to eating fat, they often experience gall bladder problems so extreme that removal is required. Several people, even young teens, found that after being on Nutri-System and Jenny Craig that their gall bladders had "turned off" and they couldn't adjust to processing normal fat regimes again. Some sued and these low-fat systems were required to change their formats.
Ultimately, low-fat is more dangerous to the system than low carb.