I did 16:8 for exactly 47 days. I know because I counted. And it was fine. Like, genuinely fine. I lost weight, I felt okay, it wasn't hard.
But "fine" is a dangerous word. "Fine" means you're not optimizing. You're just... existing. And I'm not about that life.
The switch happened because of a random Tuesday. I was busy with a client project and I missed my 12 PM eating eating-window-planner. Didn't eat until 2 PM. So that day I accidentally did 17 hours. And the next morning, I was down 0.4 kg. Which was more than my average daily loss on 16:8.
Coincidence? Maybe. But I tried it again the next day on purpose. 17 hours. Same result — another drop. Then 18 hours. Another drop. I ran this experiment for two weeks: 7 days of 16:8, 7 days of 18:6, same calories, same foods.
The data was annoying. 18:6 won by a significant margin. Not like "wow, miracle diet" margin, but consistently 30-40% more weight loss per week. And my energy was more stable on 18:6. Fewer afternoon crashes.
Here's what I think is happening. That extra 2 hours pushes me deeper into ketosis. On 16:8, I was probably just barely getting there on good days. On 18:6, I'm solidly in fat-burning mode for at least 4-6 hours before I eat. The metabolic-analyzer analysis tab on my calculator estimates this — and it's been pretty accurate for my experience.
The social cost is real though. 18:6 means eating between 2 PM and 8 PM. Brunch invitations? Nope. Early dinners with friends? Tricky. I've become "that person" who shows up to events and just has water. It's fine, I've accepted my fate.
One hack that helped: I moved my workout to 1 PM, right before I break my fast. So I'm exercising in a fasted state, then eating immediately after. The combination feels incredible. Like my body is just soaking up every nutrient.
Would 20:4 be even better? Probably. But I'm not there yet mentally. 18:6 feels sustainable. It feels like something I can do for years, not months. And sustainability beats intensity every single time.
If you're stuck on 16:8 and not seeing results, try pushing it by just one hour. That's it. One hour. See what happens. The data might surprise you.