Trans fats are made by solidifying oils during a process called partial hydrogenation.The oil is heated, and hydrogen bubbles are passed through it. During this period, the oil acquires a portion of the hydrogen and becomes denser than normal.

Margarine, which is made as described above, accounts for nearly one quarter of the trans fats we consume today. If youre eating margarine to avoid the saturated fats found in butter, youre doing your body a huge disservice, as the trans fats in margarine are far worse for your body than the fats found in butter. Fortunately, there are now some varieties of margarine without trans fat.