Keeping your blood healthy and looking/feeling good are both important issues when considering fat. The blood can get unhealthy for many reasons, not just too much fat, but also too much protein, heavy metals, parasites, etc. which essentially makes the blood thick, sluggish, cloggey, unhealthy. I don't think the controversy/question for healthy blood and even weight loss is necessarily too much fat or protein but what kind of fat you are consuming and how your body efficiently metabolizes it. Coconut oil, olive oil, animal fat are very good fats for you, canola oil, corn oil, margarine, etc. are very bad and our body does not efficiently metabolize them and then they get in our blood stream. Including low fat foods, they are an incomplete food as well as pasturized dairy products. The components which mother nature naturally provides in these healthy foods are stripped away leaving us with compromised food that our body cannot readily metabolize. For example raw milk has enzymes and bacteria that naturally help our body efficiently digest it. Where as pasturized and low fat milk only relies on our digestive juices to metabolize it and especially if our digestive system is compromised in anyway or we may have candida infection our body cannot efficienlty get rid of the fat/protein and it leaks through our intenstines into our blood stream undigested making our blood unhealthy. Very healthy people can still have compromised digestion, you cannot necessarily tell by looking at them. We all are striving to eat optimally.
I would recommend for anyone who is interested in their health especially their blood health to heave their blood looked at under a high powered microscope. It is an eye opening experience to see what kind of state your blood is in. It just takes a drop, and a high powered microscope, we had ours looked at in an alternative/wholistic doctor's office.
It is the same if you eat cooked vegetables/grains/and meat or unsoaked/sprouted grains,nuts and seeds. The enzymes for digestion have been mostly cooked out, the grains, nuts, and seeds have enzymes inhibitors.
This is why we sprout and lacto ferment our grains, and eat lots of fermented foods with our meats such as sauerkraut or eat our foods raw. Fermented foods are super raw foods with tons of enzymes to aid in digestion and raw foods are intact and also provide us with their natural enzymes so we are working with nature as our body intended; not fighting it. If all else fails it does not hurt to also take an enzyme supplement/capsule plus a dose of probiotics to aid in digestion.
So I see this matter not as a fat issue because the good fats are very good and our body needs them to function properly. It is a health issue of the digestive system. Too many doctors treat the symptom and not the all around cause and do not treat the body as an interconnected wholistic system.
I hope this helps.