Oils may be “fattening” in the sense that they’re pretty high in calories compared with other foods. All oils have around 120 calories per Tbsp, so you can easily gain weight if you use too much. Even butter has fewer calories than oil (100 per Tbsp of butter) because of its water content.
What’s more, “whipped” butter sold in a tub has even fewer calories—about 60 to 70 per Tbsp, thanks to the air that’s been incorporated into the mix. And tub “light” margarine spreads have only 30 to 50 calories per Tbsp.
But since oils contain fats that are good for you, you’re better off getting that 120 calories from a healthy oil rather than stick or tub butter. By the way, if you’re inclined to cut out fats entirely, don’t: We do need some fat to be healthy. Without it, our bodies can’t absorb fat-soluble vitamins like A, D, E and K, and we miss out on fatty acids that are essential for the health of your skin, hair, heart and brain—and just about every other part of your body.