A few questions around exercise (mainly climbing + calorie counting)

Hello! I just started IF at a 16:8 ratio after gaining around 20 lbs over the holidays. Previously I was maintaining pretty well for a few years but between the holidays and getting Covid in the middle of i I gained some weight. So, I’m giving this a try to get back on track.

I’m normally a very active person - I rock climb a few days a week and I also run when it’s warmer out. On top of that, I live in a walkable city and probably get 15-20k steps per day on average. I only started IF last week and I deliberately didn’t exercise so I could get into the habit first and then gradually add my regular routine back in. For the most part, by the end of the week I was pretty used to it and only feeling really hungry by around 11. Today was my first day climbing since starting and I’m not gonna lie it didn’t feel great. I had to stick to easier climbs because I just felt weaker.

Similar to running, I always notice my best performance days are when I’m working off a larger meal. Today I just wasn’t feeling nearly as sturdy. It could have been because I went climbing at the very end of my fasting period but I’m just wondering how people who are naturally very active approach this. Do you find that the timing matters a lot in regards to performance? Also in general how much do y’all calorie count? For the first week I counted only to get an idea of how many calories on average I was eating while only restricting time. Thankfully I’m already in the habit of eating pretty balanced but I may continue doing it over the next few weeks mostly to make sure I’m eating enough as I’m working up to my standard routine