Dietary cholesterol accounts for 10% to 30% of the total. The majority of the cholesterol is made by the liver. Donating plasma has a limited effect because the body is going to replace what is removed faster than you can donate plasma. In patients with familial hyperlipidemia (severly high cholesterol due to too much production by the liver), plasmaphoresis can be helpful. Unlike donating blood or plasma, plasmaphoresis "washes" the plasma of cholesterol continuously for several hours and returns the plasma, minus the cholesterol, back to the body. During this process, the entire volume of plasma can be "washed" several times over. Plasmaphoresis must be performed every three days or so to have a meaningful effect. Within a few days to weeks of stopping the plasmaphoresis, cholesterol will return to what it was.
As far as the MacDonald’s meal you consumed, within four to six weeks of changing your diet for the better, you will achieve the maximum benificial effect on plasma cholesterol. It will take much longer (six months to several years) of eating well to achieve the maximum effect in terms of removing atherosclerotic plaque from the blood vessels, but donating plasma or blood is not going to have an impact.
Without taking drugs to control cholesterol, diet will lower cholesterol by 10% to 30%, exercise will lower the bad cholesterol and raise the good cholesterol (HDL cholesterol) by up to 30%, and weight loss if your percent body fat is above normal, will have beneficial effect, but some people just have bad genes. If it is in the genes to have bad cholesterol, then the only thing that is going to help is a 3-hydroxy-3-methyl-glutaryl-CoA reductase (HMG CoA reductase) inhibitor such as Lipitor (atorvastatin), Crestor (rosuvastatin), etc. There are no shortcuts.
