Intermittent Fasting Apps: What I Used for 8 Weeks

I Gained 15 Pounds During Lockdown and Decided to Do Something About It

Not a great look, I'll admit. But that's how I ended up here — three years ago, frustrated with how I looked in video calls, staring at intermittent fasting apps on the App Store. I'd heard about IF from a friend who swore by it.16:8 this, 18:6 that. It sounded like a diet with extra steps.

But I was stuck at home with nothing better to do, so I figured I'd try it properly. Eight weeks. Two different apps. Here's what actually happened.

Why Intermittent Fasting Isn't Just "Not Eating"

Before we get into the apps, let me clear up what IF actually is — because I went in thinking it was just "eat less," and that's only partially right.

Intermittent fasting is an eating pattern where you cycle between eating and fasting windows. The most common version is 16:8 — sixteen hours of fasting, eight hours of eating. During your eating window, you can eat normally (within reason). The goal isn't necessarily calorie restriction; it's giving your body extended periods without food so it can tap into stored fat for energy.

There's actually some science behind this. When you eat, insulin rises to process the food. When you fast, insulin drops, and your body starts burning stored energy. The longer your fasting window, the more time your body spends in that fat-burning state.

But here's what nobody tells you: IF is only partially about what you eat. The other half is tracking your fasting window consistently. That's where apps come in — and where they vary wildly in quality.

App #1: Zero — The Minimalist Approach

Zero was the first app I downloaded. It's owned by Probe, the same company behind the Zero fasting tracker, and it's about as simple as fasting tracking gets.

You set your eating window — say, noon to 8 PM — and the app tracks how many hours you've fasted. It shows you a clean timer: how long you've been fasting, how long until your eating window opens. When you hit your goal, you get a celebration animation (yes, really — a little firework display). The gamification is corny but actually worked on me. I found myself wanting to "complete" my fast just to see the animation.

What Zero does well: it's clean, it's simple, and it sends reminders when your eating window opens and closes. The fasting protocol presets are useful — 16:8, 18:6, 20:4, even a custom option. You can sync with Apple Health to track weight, though I found the weight tracking redundant since I was already using a separate scale app.

What Zero doesn't do: meal logging, calorie tracking, or any kind of nutrition advice. It's purely a fasting timer. That was actually fine for me in the beginning — I didn't want to deal with tracking every meal while I was still figuring out the fasting part.

The catch: Zero's premium subscription is $8.99/month or $59.99/year. The free version works fine for basic tracking, but the premium adds custom fasting schedules, detailed analytics, and meal reminders. I paid for the first month, then dropped it when I switched apps.

App #2: Fastic — The Budget Option

I switched to Fastic after a friend recommended it. The big selling point: it's free, with no premium paywall blocking core features.

Fastic works similarly to Zero — you set your eating window, track your fasts, and get reminders. The interface is slightly busier, with more animations and visual elements than Zero's minimalist approach. There's a community feature where you can see other users' fasting streaks, which I found motivating in a guilty-pleasure way.

What I liked about Fastic: the water and meal logging was built in. During my eating window, I could log what I ate and get a sense of whether I was overeating during my feeding hours. This was actually the feature that made me switch — I kept "accidentally" eating way too much during my eight-hour window, which was defeating the purpose.

What I didn't like: Fastic's fasting protocols are less customizable than Zero's. The presets are there, but if you want something like 14:10 (a gentler beginner-friendly fast), it's not obvious how to set that up. The app also showed me ads in the free version, which was annoying but not a dealbreaker.

The weight tracking synced with my Apple Watch, which was useful. After eight weeks, I'd lost about six pounds — not dramatic, but consistent. I was eating more consciously during my feeding window, and the fasting window was helping me avoid late-night snacking that was probably my biggest calorie source.

The Honest Verdict

Here's what I actually learned after eight weeks: the app matters less than you'd think. Both Zero and Fastic will get the job done if you're consistent about logging your fasts and honest about your eating window.

The real question is whether you want additional features. If you're just starting IF and want something clean and distraction-free, Zero is worth the subscription. The interface is better, the analytics are more detailed, and the fasting protocols are more flexible.

If you want to track meals alongside your fasting and don't want to pay for a premium subscription, Fastic is the better choice. The meal logging during your eating window is genuinely useful, and the community features add a layer of accountability that solo apps lack.

What I'd tell myself at the start: IF isn't magic. The six pounds I lost came from being more mindful about what I ate during my feeding window, not from the fasting itself. The apps helped me stay consistent, but the work was mine.

That said — if you're the kind of person who snacks late at night without thinking about it, IF forces you to draw a hard line. For me, that was worth downloading an app.