It`s hard to imagine a time when fats were not controversial and did not strike fear in the hearts of dieters. Just the mention of fat-loaded words like butter and bacon can trigger powerful reactions! And yet it has only been in the past 50 years or so that our relationship with fats has become such a problem. Of the three primary macronutrients, fat provides the most energy (measured in calories) by weight. Fats have many other important jobs. Fats are a crucial source of raw materials. Dietary fat is a fundamental building block and our bodies use it in a variety of ways. We use fats to build hormones and neurotransmitters. Fats also aid in the absorption of fat-soluble vitamins A, D, E, and K, and play key roles in regulating inflammation, chemical signaling and the metabolism of other nutrients.