Nerin
Great to hear about your success along the road of health and wellness! 40lbs lost and kept off is a great effort - well done!
Chalk one more up for the 'full body split' here. Compound movements utilising progressive resistence (i.e., once form is correct, keep adding weight every session) are far and away the most effective way of getting novice trainees big and/or strong (no you won't be able to keep adding weight every session forever but as a beginner I'd say it'll be a surprisingly long time until you stall ... that's a topic for another time though).
Consider something like this (from Mark Rippetoe's book
Starting Strength - if you don't have a copy get one!!)
Workout A
Squat 3x5
Press 3x5
Deadlift 1x5 (can substitute Powercleans if and when you feel like it)
Workout B
Squat 3x5
Bench press 3x5
Back Extensions 3x5
Chins 3x5
Lift Mon - Wed - Fri (or whenever your schedule allows, ensuring you don't lift on 2 consecutive days) and alternating Workout A, B, A, B, A, B etc...
Insert situps/bridges/misc 'ab work' of choice after each workout until you're squatting/pressing heavy enough to fry your 'core' without added help.
Or even more basic: Squat, Press, Dip, Chin 3x5 for everything rinse and repeat 2 or 3 times a week.
The human body has no concept of muscles as individual entities so why train like it does? The body is one big system and is most effectively trained (at the novice - intermediate level) as a whole unit.