My doctor gave me the same option last fall: improve my cholesterol in 6 months or go on medication.
I started eating stuff like oatmeal, egg beaters instead of eggs, trans-fat free margarine instead of butter, olive oil, ground flax seed, more soluble fibre, omega 3 capsules, etc. It lowered my levels enough to keep me off medication.
Since my last test, I've added daily exercise. Exercise is important to improve cholesterol levels, too.
And, yes, I'm afraid excess weight/body fat can increase cholesterol levels.
So can smoking, excessive alcohol, and your genes, among other things!
The NHLBI is one of many good sources of information: nhlbi.nih.gov/health/dci/Diseases/Hbc/HBC_Treatments.html