词汇解释题。考查对上下文意思的理解。根据最后一段“leach”所在句“However, when fat cells start to become insulin resistant, the lipids start to leach out of the fat cells and rise in the bloodstream, ”可以知道：血脂开始从脂肪细胞中渗出并在血流中增加。因此可以推测出leach和leak同义，意为“泄露，露出”。故D项为本题正确答案。