It's really hard to have any definitive study about the digestive system because there are a number of interrelated systems and you can never be fully confident that the trends you are seeing are because of the stimulus you changed. To that end I can only offer my own experience.
- As I lost weight all my numbers improved: blood pressure, cholesterol levels, etc.
- Cholesterol is most affected by exercise--i.e. the more active you are the less bad cholesterol you have in your system.
Now the folks at my weight loss center suggested the following:
- Lean protein (90% lean or better for red meat, white meat for poultry, or fish)
- Keep reasonable portion sizes. I.e. land meat is the size of your closed fist, seafood is the size of your open hand, eggs are limited to 2 whole eggs at a meal.
It very may well be the type of protein you are eating that is contributing to the high cholesterol. Even though I don't have links for you, there are studies that show that dietary cholesterol doesn't directly translate to blood cholesterol. Higher blood cholesterol can be a symptom of other things going on in your body.
Last thought is this: fish is the most protein dense food you can eat, which will help lower your cholesterol and not overdo the calories. Essentially an 8oz tilapia filet has something on the order of 40g of protein and only about 300 calories. The oils in the filet are good Omega-3s, and not the harmful Omega-6s. Most of my lunches are some form of sea meat right now.