Some fats are better than others.

As part of a healthy diet, 20-35% of total calories should be unsaturated fats. Sources of unsaturated fats include fish, nuts and vegetable oils.
Trans fat and saturated fat should be limited to less than 10% of total calories. Examples include lard, butter, high-fat red meats and some margarines.
Every 45 seconds, someone has a heart attack. Diets high in saturated fat have been associated with increased risk of heart disease and stroke. Choosing unsaturated fats can help reduce your risk.
Margarines that are made without the addition of trans fat are the best option. No matter what you choose, remember to consume fats in small amounts.
Salmon, tuna and trout contain a type of fat that can reduce your risk of heart disease. Try to eat a 4 ounce serving of fish three times per week.
Margarine regular .......................1 tsp
Margarine lower fat ...................1 Tbsp
Butter regular .............................1 tsp
Butter, reduced fat .....................1 Tbsp
Oil ............................................1 tsp
Mayonnaise regular .....................1 tsp
Mayonnaise reduced fat .............1 Tbsp
Salad dressing regular ..............1 Tbsp
Salad dressing reduced fat ........2 Tbsp
Sour cream regular...................2 Tbsp
Sour cream reduced fat ............3 Tbsp
Cream Cheese regular ..............1 Tbsp
Cream Cheese reduced fat ...11/2 Tbsp