Fats are important.
They are used for:
Moving around fat soluble vitamins
Production of corticosteroid hormones
Fats are referred to as fatty acids in the science realm. The three dietary fatty acids are polyunsaturated fatty acids (PUFAs), MUFAs (monounsaturated) and saturated (SFA).
The categories are determined by how many carbon-carbon double bonds there are.
Ideally we want to be eating all of these. None are ‘good’ fats or ‘bad’ fats. We don’t do that there. Not for gooey reasons, just because there really is no good or bad when taking a deeper look at what fatty acids do and how they work in the body.
Cholesterol is not a bad boy, he’s just had some bad press.
Average males in the US consume an average of 362 mg per day of cholesterol. The liver and intestines then go ahead and make an additional 1,000 mg on their own. Overall the body makes cholesterol on its own and the amount being obtained through the diet is usually minimal in comparison.
Only about half of the intestinal cholesterol is absorbed; the remainder is excreted. Most of the cholesterol from the diet is in the wrong form to be useful and so must be hydrolysed into to free cholesterol to be absorbed anyway. Overall, dietary cholesterol is usually not a big deal.
The ratio of total cholesterol to HDL cholesterol (or ‘good’ cholesterol as it’s referred to by the gurus) is a better indicator of potential CVD issues than just total cholesterol.
Meta analyses show that swapping SFA for PUFAs (kcal for kcal) in the diet tends to reduce the risk of coronary heart disease.
There isn’t sufficient data at the moment to link MUFAs to heart disease but they are packed with good stuff so should not be discounted.
The risk of CHD seems to be more complicated than just cholesterol. Genetics, diet, obesity, inactivity and other lifestyle factors all play roles.
My general recommendation is to eat a mixture of the dietary fats with a focus on consuming the majority from PUFAs and MUFAs as these seem to be less abundant in western diets.