I've always been a "eat before the gym" person. Pre-workout banana, maybe some protein. Standard stuff. But I kept reading about fasted training and how it amplifies fat oxidation. So I tried it for a month.
The first week was rough. I do my workouts at 1 PM, right before I break my fast on 18:6. So I'm 17 hours fasted when I hit the gym. Day 1, I felt weak. Like, embarrassingly weak. I dropped my usual weights by 20% and still struggled.
Day 3 was better. Still not my strongest, but I wasn't dying. Day 5, something clicked. I felt this weird focus. Like my brain was dialed in because my body wasn't busy digesting. I finished my workout and wasn't even hungry yet — which never happens when I eat before the gym.
By week 2, I was back to my normal weights. Not stronger, but not weaker either. The difference was my energy after the workout. Usually I feel drained post-gym and need a big meal. Fasted, I felt... light? Energized? It's hard to describe.
Week 3, I added HIIT. This was where it got interesting. Fasted HIIT felt harder during the session, but the recovery was faster. Less soreness the next day. I don't know if that's real or placebo, but I noticed it consistently.
Week 4, I tried a heavy leg day fasted. Bad idea. I got dizzy on squats. Not dangerously dizzy, but enough to stop the set. I finished the workout with lighter weights and ate immediately after. Lesson learned: heavy compound lifts need fuel.
So my current compromise: fasted cardio and moderate lifting are fine. Heavy lifting days, I break my fast 30 minutes before the gym with something light — banana or a rice cake. Best of both worlds.
The calculator's eating eating-window-planner planner actually has a workout time field now, because of this experiment. It helps you figure out whether to schedule your workout before or after your eating eating-window-planner. Small feature, but it came from real pain.
If you're curious about fasted training, start with light cardio. Don't jump into heavy lifting on day one. Your body needs time to adapt to using fat as fuel instead of glucose. Give it 2-3 weeks before judging.