I would caution against overemphasizing the science - it's a great idea but in practice can lead to nitpicking and bikeshedding. It's mostly because the science

I would caution against overemphasizing the science - it's a great idea but in practice can lead to nitpicking and bikeshedding. It's mostly because the science isn't as precise as we would like it to be. There are very few things that we know well - exercise is good for you, you should drink plenty of water, resistence training has many benefits, cardio has some benefits too, you shouldn't eat too much sugar - high level stuff like that. I would suggest picking something that's generally accepted and try it out for a while - if you're going to the gym, learn (with a coach or by yourself) how to do stuff like squat, deadlift, press, bench press and pull-ups and pick a simple program that focuses on getting stronger in these movements. The book Starting Strength covers this in more detail but you can find articles and videos that summarize it if you don't want to read a book; or you can pick some other program like one of the stronglifts.com progressions - the details of the program don't matter as much as focusing on these main movements and being on a program where you make progress by increasing the weight you lift over time.