Nutrition timing is irrelevant unless you're an endurance trainee.
Calorie count is what matters the most.
The amount of carbs/fats your body will responds best to varies from someone to another.
Conclusion: play around with your carb and fat intake and find which one you respond best to...
You can do squats as suggested and finish off with leg press if you like.
As for your lower back problem, go as low as you can without letting your butt comes off the bad or allowing your lower back to round.
P.S. our body mechanics are slightly different so if you feel uncomfortable doing leg...
IF is just an eating style that may or may not fit your schedule. Focus on what really matters:
Find your maintenance calories and eat around 500 cals less than that to lose 1 pound per week. If you aren't losing then your maintenance is actually lower than you thought so you'll need to lower...