I train for powerlifting, so my goals may be a bit different, but here’s my experience.
I started doing a 16/8 IF about 4 months ago. I improved my body composition with no loss of strength. I lost about 5 lbs of fat in 2 months without eating particularly clean just by moving it all into an 8 hour window. My training at the time was a rehab cycle, so I wasn’t even training all that hard. My energy did not change noticeably - I spent about 4 months beforehand systematically eliminating foods that my body doesn’t tolerate, and I think that made a much larger change in my subjective energy.
However, it didn’t work for me for a lot of logistic reasons. I train with a crew at 7pm during the week, so getting home at 9pm and eating for 8 hours was out of the question. I found that a feeding window from 2pm to 10pm worked pretty well, but I just couldn’t find the happy medium between eating too much before training and being sluggish and eating too much after training and not being able to sleep.
On off days I also had a bad habit of getting stuck at work or in my lab until pretty late and missing the opening of my feeding window - dismissing hunger pangs has never been hard for me, and once I get past the first wave I can fast all day.
After about 2 months of 16/8, I was still getting hungry at 11 or 12 pretty consistently, so now I eat my first and largest meal around then, eat again sometime in the afternoon, then eat something small in the evening. On training days I have shakes around my training and a small meal after. If I’m really hungry, I might have a massive meal after training, but I have to listen to my body or I risk not being able to get to sleep.
For example, this is what monday looked like:
Meal 1 (11am): 1 lb grassfed beef patties, 5 strips of bacon, 3 sweet potatoes, 1 scoop rice protein, kefir
Meal 2 (3-4pm): 0.5 lb pork chops with applesauce, apple with 3-4 tblspoons peanut butter, 1 scoop rice protein, maybe some greek yogurt or kefir
Meal 3 (7-8pm): 0.5 lb pork chops with applesauce, green beans with real salt and grass-fed butter, maybe some greek yogurt or kefir
I can’t have milk proteins or eggs daily or I would. I eat wheat very rarely and other grains sparingly. I also eat other random things between meals - terra chips, oatmeal, nuts, basically whatever. As long as I avoid foods my body doesn’t tolerate, I don’t worry about eating clean, just eating enough - but avoiding wheat means avoiding about 99% of junk foods so I can’t always dirty it up as much as I would like when I need to get calories in.
Sometimes meal 2 is the biggest meal (if I have to be physically in my lab around lunch and I don’t have enough food prepared for meal 1), but I feel best if meal 1 is largest.