If you want to lose weight watch what you eat!!! Maybe try getting some exercise! The degree in which a fat is saturated refers to how many or how densely surrounded it is in hydrogen molecules. Polyunsaturated has multiple gaps, monounsaturated one (and this is the best bet to add for weight loss, not poly), and saturated fat is completely encircled with hydrogen.
Fat is the most calorically dense macronutrient, but probably not the most fattening. Sugars and starches to a larger degree contribute to fat deposition. Adding fat to those meals slows their digestion, thus lowering the impact on blood glucose.
If you need to know more, request a hub from me, but be specific!