Zero Fasting App Review UK (2026)
The world's most popular intermittent fasting app - but is the premium subscription worth £55/year?
What is Zero?
Zero bills itself as "the world's most popular intermittent fasting app" and has been featured in publications from Women's Health to The Joe Rogan Experience. The app gained additional publicity when Elon Musk mentioned using it for intermittent fasting.
The core function is simple: start a timer when you begin fasting, stop it when you eat. But Zero adds educational content about fasting zones (when your body shifts into ketosis, autophagy, etc.) and tracking features to monitor your progress over time.
Popular Fasting Protocols in Zero
- 16:8: 16-hour fast, 8-hour eating window (most popular)
- Circadian rhythm (13-hour): Aligned with natural sleep/wake cycles
- 18:6: 18-hour fast, 6-hour eating window
- 20:4: 20-hour fast, 4-hour eating window
- OMAD: One meal a day (23:1)
- Custom: Set your own fasting duration (up to 7 days)
Key Features
- Fasting timer: Start/stop timer with visual progress tracking
- Fasting zones: See when you enter different metabolic states
- Streak tracking: Maintain motivation with fasting streaks
- Journal: Log mood and notes during fasts
- Educational content: Articles and videos on fasting science
- Food tracking (Premium): Basic calorie and protein logging
- Body composition (Premium): Weight and measurements tracking
- Insights (Premium): Detailed analytics on your fasting patterns
Zero Pricing UK
Zero UK Pricing (January 2026)
| Plan | Price (USD) | Approx GBP |
|---|---|---|
| Free | $0 | Free |
| Monthly | $9.99/mo | ~£8/mo |
| Annual | $69.99/yr | ~£55/yr |
Free vs Premium
Free tier includes: Fasting timer, basic journal, mood tracking, fasting zones visualisation, streak tracking. This is genuinely functional for most fasters.
Premium adds: Food and protein tracking, weight logging, detailed insights and analytics, longer fasting history, body composition tracking.
The free version offers more value than many competitors' free tiers. Premium is really for those who want everything in one app rather than using Zero alongside a separate food tracker.
Pros & Cons
Pros
- Well-designed, clean interface
- Good free tier functionality
- Educational content on fasting science
- Fasting zone visualisation
- Streak motivation system
- Multiple fasting protocols
- Journal and mood tracking
Cons
- Premium price feels steep (~£55/yr)
- Basic food tracking vs dedicated apps
- Limited calorie/macro tracking
- It's essentially a fancy timer
- Some features available free elsewhere
- No meal planning or recipes
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What Real Users Say
Zero has received over 500,000 five-star ratings across app stores:
"Really useful to work towards an 8 hour eating window. Software user experience is good." - UK Trustpilot review
"The app worked well as a fasting timer, but offered limited support for calorie and macronutrient tracking." - Fortune review (3.5/5)
Common praise: Clean design, helpful fasting zones, good educational content, motivating streaks
Common complaints: Premium too expensive, basic food tracking, essentially a timer with extra steps
Who Zero Is Best For
Fasting Beginners
The educational content and fasting zone visualisation help newcomers understand what's happening in their body.
Streak Motivated
If maintaining streaks motivates you, Zero's tracking can help build the fasting habit.
Simple Needs
If you just want a timer and don't need detailed calorie tracking, the free tier works well.
Science Curious
The educational content on autophagy, ketosis, and metabolic switching is genuinely interesting.
Who Should Look Elsewhere
- Detailed food trackers: Zero's food logging is basic compared to dedicated calorie apps
- Budget-conscious: Premium is expensive for a fasting timer - free alternatives exist
- Macro counters: If you need detailed macro tracking, use a dedicated nutrition app
- Those who need more than a timer: The core function is timing fasts - everything else is extra
The Bottom Line
Zero is a polished, well-designed fasting app with genuinely useful educational content. The free tier is functional enough for most intermittent fasters - you get a timer, fasting zones, streaks, and basic tracking.
The premium subscription at ~£55/year is harder to justify. You're paying a lot for what's essentially a timer with food tracking that doesn't match dedicated nutrition apps. Many UK users feel a simple phone timer achieves the same result for free.
Our verdict: Try the free version. If you find the fasting zones and educational content valuable, and want everything in one place, Premium might be worth it. But for most people, the free tier plus a separate calorie counter is the better value combination.
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