5:2 Diet Explained: How It Works and How to Start
The 5:2 diet means five normal eating days and two low-calorie days weekly. Learn calories, meal ideas, pros, cons, and safety basics in this full guide.
8 min read
Master your metabolism
Fastive is a minimal, professional intermittent fasting companion — smart timer, metabolic phases, hydration tracking, and AI-powered meal insights in one app.
Free to start · No account required · 9 languages · iOS & Android
Built for consistency, not clutter
Most fasting apps overwhelm you. Fastive focuses on what matters: knowing where you are in your fast, staying hydrated, and building a streak you can see.
| Feature | Benefit |
|---|---|
| Metabolic phase timeline | See when your body enters fat burning, ketosis, and autophagy |
| Smart schedule | Set your last meal time — Fastive calculates your fasting window |
| Offline-first | Log fasts and water even without a connection |
| Privacy-first | Start as a guest; add email only if you want sync across devices |
| 9 languages | English, Türkçe, Español, Français, Português, 日本語, 한국어, Italiano, Polski |
Fastive vs generic timer apps
Generic fasting timers count hours. Fastive is an intermittent fasting app built for consistency — it adds metabolic education, daily logging, health sync, and optional AI meal insights so you know not just how long you fasted, but where you are in the process.
| Capability | Generic timer apps | Fastive |
|---|---|---|
| Fasting countdown | ✓ | ✓ |
| Metabolic phase timeline | — | ✓ |
| AI meal photo analysis | — | ✓ |
| Water & weight logging | — | ✓ |
| Apple Health / Health Connect | — | ✓ |
| iOS Live Activity | — | ✓ |
| Offline-first logging | — | ✓ |
| Guest mode (no account) | — | ✓ |
Start fasting in three steps
- 1
Pick your plan
From beginner-friendly 12:12 to advanced OMAD and 5:2
- 2
Start your timer
Track elapsed time, remaining time, and your current metabolic phase
- 3
Log & improve
Water, weight, meals; optional AI scan estimates calories from a photo
Everything you need in one app
Fasting Timer
Start, pause, or log a retroactive fast if you forgot. See eating vs fasting windows on your home screen.
Metabolic Phases
Visual timeline: Fed State → Fat Burning → Ketosis → Autophagy → Deep Autophagy. Educational, not medical diagnosis.
AI Meal Scanner
Photograph your meal after a fast. AI estimates calories, protein, carbs, fat, and whether the meal may break your fast. One scan per day.
Water & Weight
Daily water goal with quick-add buttons. Weight history chart. Optional import from Apple Health or Health Connect.
Apple Health & Health Connect
Read latest weight and today's steps. Write completed fasting sessions back to your health app.
Live Activity (iOS)
Track your fast from the Lock Screen without opening the app.
Find your fasting protocol
| Plan | Fast | Eat | Level | Free |
|---|---|---|---|---|
| 12:12 | 12h | 12h | Easy | ✓ |
| 14:10 | 14h | 10h | Easy | ✓ |
| 16:8 | 16h | 8h | Moderate | ✓ |
| 18:6 | 18h | 6h | Moderate | ✓ |
| 20:4 | 20h | 4h | Hard | Premium |
| OMAD | ~23h | ~1h | Extreme | Premium |
| 5:2 | 2×24h/week | — | Hard | Premium |
Go further with Fastive Premium
Unlock advanced plans (20:4, OMAD, 5:2), activity heat maps, achievement badges, and deeper analytics. Cancel anytime through the App Store or Google Play.
See Premium →Common questions
- What is Fastive?
- Fastive is an intermittent fasting app for iOS and Android. It includes a fasting timer, metabolic phase timeline, water and weight tracking, optional AI meal photo analysis, and Apple Health / Health Connect integration.
- Is Fastive free?
- Yes. You can download and use Fastive for free with plans 12:12, 14:10, 16:8, and 18:6. Premium is an optional subscription for advanced plans and analytics.
- Is there a free trial for Premium?
- No. Premium subscriptions charge at purchase through the App Store or Google Play. You can cancel anytime before renewal.
Intermittent fasting guides
New to IF? Read our guides on 16:8, OMAD, autophagy, and more — then track your chosen protocol in Fastive.
Autophagy and Fasting: What Science Says and What to Expect
Autophagy fasting pairs with intermittent fasting in popular science. Learn what autophagy is, how fasting may relate, and realistic timelines—not hype.
6 min read
Breaking a Fast: What to Eat for Your First Meal
Breaking a fast matters for comfort and digestion. Learn what to eat first, smart portions, foods to limit, and when to see a doctor—an educational guide.
7 min read
