Large studies established links between saturated fats and heart disease. After the second world war, most of the dietary experts advised people to reduce fat intake not only, because of the heart connection but also because fat has more calories per gram than protein or carbs and was also assumed to contribute more weight gain.
Many people did, but they often replaced lost calories with large amounts of refined carbs. The lesser amount of fat consumption was accompanied by higher rates of overweight and obesity. Fat also has a little direct effect on blood sugar levels. It helps you to absorb certain kinds of vitamins and nutrients.
Saturated fat contributes to clog arteries and cardiovascular disease. MUFA (Monounsaturated fat) and PUFA (Polyunsaturated fat) actually protects your health by improving your cholesterol profile.
Trans Fats are a terrible type of fats for your health. This type of fats raises harmful LDL cholesterol, increases inflammation, and higher chances for blood to get clotted.