Eat before or after exercise?

For "real" workouts, before and after. This is not weight management related, but performance. If you don't care about the latter or you just exercise to lose weight then it's not as crucial - just don't pass out and you'll be fine.

As for what to eat, no fiber, no high fats, low protein, mostly carbs if the workout will be hard. No fun tasting your food twice (happened to me quite a few times). I read somewhere a guideline that cited 100 calories tops for each hour before a really hard workout, topping at 4 hours where the stomach was considered to be fully emptied. So, only have 30 minuts? a gel. 2 hours? a couple of pieces of toast and jam. I think this was for aerobic exercises, though - not for going to the gym.

Let's say a 2+ hour bike race, or a 4+ hour ride. Sure, you can do them fasted, but you're unlikely to do them well. So I have good meal 4 hours before, then a small snack about 40 minutes before, maybe during warmup. Sipping from an energy drink and maybe a gel, banana, or something easily digestible. As for "you don't need to be fueled" - I don't eat or drink much or at all for 1 hour events, but I find I have better finishes if I drink and fuel my workouts. I think this mostly applies to endurance athletes and especially cyclists since it's relatively easy to eat on the bike.

Then about 400 calories with about 25 g of protein quickly afterwards to facilitate recovery. Again, if you're just doing this to lose weight it is not that important - have a meal whenever it suits you. In my case I'm likely to have another strenuous session in the next 12 to 24 hours, and this helps me.

This is the recommendation from the gym I participate in
Workout type: if it involves elevated heart rate, sweating, HIIT type….Do not eat within 2-3 hours prior to work out.
Workout time. Avoid food for early morning workout
Weights/Lifting / Training. You can eat as close to work out as possible