Colin Carmichael’s book Crunch Cholesterol free download (.pdf). What is Cholesterol? All this talk about cholesterol but do we know what it is? Well, it’s essential for life. Cholesterol is a lipid molecule found in all animal cellular membranes. Cholesterol maintains the structural integrity and fluidity in animal cells, as opposed to the rigid cell membranes of plants. Cholesterol also serves as a precursor for hormones that you’re probably familiar with: cortisol, testosterone, estrogen, vitamin D, etc. Cholesterol is one of many building blocks in your body. Cholesterol is protecting your arteries. So why is cholesterol, in particular, demonized by doctors and health professionals? The cholesterol folk tale goes something like this: cholesterol clogs arteries and causes heart attacks; however, cholesterol is a not a free roaming substance in your body that greedily decides to stick to your arteries. The truth is that cholesterol is produced for healing purposes.