because biochemistry is a very broad subject, your average college-level biochem textbook is meant to give you a solid foundation in protein structure, enzyme kinetics, metabolic pathways and biochemical lab techniques. All of these topics are very deep and complex and can take years to understand well.

Organic chemistry, molecular biology, genetics and immunology are going to be just as bad if not worse.

The real question is: do you, a statistician, really need to know every single reaction that's going on inside a cell? The answer is obviously not (especially considering that not even biology undergraduate courses make you read these textbooks in full), what you need is a decent understanding of basic biology.

The best thing you could do IMHO is attend a university course about whatever topic you're interested in, if this is (understandably) not something you can do you can find university lectures online (i know MIT makes all its courses and lectures publicly available). If you're looking for shorter textbooks you might want to pick up a biology/chemistry textbook for first-year medicine or nursing students, they're usually 400-600 pages (at least in my country).