Best Intermittent Fasting Apps in 2026: Beyond the Timer, App by App
This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about a medical condition.
Quick answer
A fasting timer is the easiest part to build and the least important. In trials, an eating window alone added little; what you eat inside it and what happens to your body decide the result. Choose an app that sees both.
Most intermittent fasting apps are timers. You press start, a ring fills, you press stop. That part is easy to build, and it is the least important part of fasting.
The research is blunt about why.
In the TREAT trial, 116 adults were randomly assigned to a 16:8 eating window or to three regular meals a day; after 12 weeks the difference in weight loss between the groups was 0.26 kg (about 0.6 lb) and not significant. In a 12-month trial of 139 adults, adding a time-restricted window to calorie restriction gave no significant extra weight loss over calorie restriction alone.
Fasting works when it helps you eat less and better — which means what you eat inside the window, and what happens to your weight and body, are the actual results. The timer is just the scaffolding.
So this guide reads fasting apps with one question: does the app see the meals and the body, or only the clock? Each app is taken one at a time.
Free and paid features were checked against App Store listings and official help pages and are current as of October 2026.
HAVIT is made by the team that wrote this guide. We've set out how each app was judged, and where HAVIT is not the best pick.
01
Three things to check before you pick
1. Is the fasting timer free — and which schedules? Several apps keep some schedules for the paid tier. If you want 16:8 and nothing else, almost any app is enough.
2. Does it log what you eat when the window opens? A fast broken with a pastry and a fast broken with eggs are different days.
Many fasting apps log food only on the paid tier, or not at all.
3. Does it see anything besides the clock? Sleep, cycle, protein and — if you take one — a GLP-1 medication all change how a fast feels and what it does. A timer cannot see any of them.
02
HAVIT — fasting, meals and weight read by one coach
| Maker | Havit Inc. |
| Price | Free · HAVIT Premium subscription |
| Free | Meal logging (search or manual entry) with calories per meal; weight, water, sleep, steps, fasting, mood, cycle and GLP-1 dose/side-effect logs; body-composition estimate; AI coach chat (daily message limit) |
| Premium | Carb, protein and fat analysis per meal and per day; remaining-calorie balance; AI Food Scan (photo); unlimited coach chat; daily check-in; workout video, guided meditation and articles |
| App Store (US) | 4.7 (159 ratings) |
| In one app | Fasting, meals, hydration, workouts, sleep, steps, cycle, mood, GLP-1 |
| Body composition | Estimated fat and lean trends, no hardware |
Free and Premium features listed for HAVIT reflect the app's default settings as of October 2026; promotions sometimes open some Premium features for free.
HAVIT is not a better timer. It is the rest of the picture. Fasting sits in the same app as meals, sleep, steps, cycle, mood and GLP-1 medication, and the AI coach reads every log together.
That is what lets it answer the questions a timer cannot. Your fasts are on schedule, but the first meal after them has been low in protein four days running, and your sleep dropped below six hours twice — fix the first meal before you stretch the window.
What you eat inside the window
Meals can be logged by search for free; AI Food Scan (HAVIT Premium) turns a photo of the meal that breaks your fast into an estimated calorie and nutrient breakdown, including protein.
The food database is drawn from public food authorities — ~486,000 entries.
If you take a GLP-1
On a GLP-1 medication, appetite is often lower and meals can drift further apart on their own. That can look like fasting without trying — and it can also mean too little protein.
HAVIT logs dose, side effects and protein next to your meals and fasts, so the coach sees the gaps for what they are.
It does not tell you whether to fast on a GLP-1. Combining a fasting schedule with a GLP-1 is a decision to make with your prescribing clinician — especially if you also take insulin or other glucose-lowering medication.
Body composition, not just weight
In the TREAT trial, among the 50 participants whose body composition was measured in person, the fasting group also lost more appendicular lean mass than the control group.
HAVIT estimates fat and lean trends with no hardware (internal comparison against InBody, n=70) — an estimate for tracking, not a medical measurement.
Where HAVIT is not the best pick
If all you want is a clean, free fasting timer with streaks, Zero and BodyFast do that with less on the screen. HAVIT is for people who want the fast, the meals and the body read together.
Who it suits: people whose fasting stalled and don't know why; people on a GLP-1 whose meals have spread out; people who want fasting, food, sleep and cycle in one app instead of four.
03
Zero — the cleanest free timer
| Maker | Zero Longevity Science |
| Price | Free · Zero Plus |
| App Store (US) | 4.8 (445,295 ratings) |
What it does well. Fasting timers, streaks, weekly trends, articles and challenges are free. It does one thing and does it cleanly.
Where it falls down. Photo meal logging, its Protein Score, water tracking, custom fasts and the mood journal are Zero Plus features. No GLP-1 logging is listed.
Who it suits: people who want a free, well-made timer and nothing else.
04
Simple — fasting with an AI coach on top
| Maker | AM APPS LTD (Simple.Life) |
| Price | Free version · Premium subscription |
| App Store (US) | 4.7 (408,139 ratings) |
What it does well. The free version logs fasts, meals, hydration, weight and activity. The AI coach Avo answers questions, and a GLP-1 Companion is being tested.
Where it falls down. On the free version Avo gives two replies a day and photo analysis once a day; unlimited use is Premium.
The GLP-1 Companion is in testing for a limited number of iOS users. It works from weight and BMI — no body-composition estimate.
Who it suits: people who want fasting plus a chat coach and are likely to subscribe.
05
BodyFast — the most schedules on the free tier
| Maker | BodyFast GmbH |
| Price | Free · Coach subscription |
| App Store (US) | 4.7 (146,135 ratings) |
What it does well. More than ten customizable fasting plans and a timer with reminders are free. The Coach subscription adds a weekly plan, daily coaching, recipes and challenges.
Where it falls down. It is built around the fasting schedule. No body-composition estimate or GLP-1 logging is listed.
Who it suits: people who want to try several fasting schedules without paying.
06
Fastic — fasting as a daily program
| Maker | Fastic GmbH |
| Price | Free · Fastic Plus |
| App Store (US) | 4.8 (246,098 ratings) |
What it does well. A fasting timer and a food and calorie tracker in the base app.
Fastic Plus builds a program around them: a daily plan, challenges, fasting buddies and the Fastic Academy.
Where it falls down. The food scanner, personalized meal plans and AI health chat are also Plus features. No GLP-1 logging is listed.
Who it suits: people who want a structured program around their fasting and expect to subscribe.
07
YAZIO — a calorie counter with a fasting timer
| Maker | YAZIO GmbH |
| Price | Free · PRO |
| App Store (US) | 4.7 (51,243 ratings) |
What it does well. A full calorie and macro counter — the barcode scanner appears in its base feature list on the App Store, not in the PRO list — and a fasting timer in the same app.
Where it falls down. YAZIO's help center lists access to all fasting plans as a PRO feature, so check which plans the free version offers before you rely on it.
No GLP-1 logging is listed.
Who it suits: people who want calorie counting first and a fasting timer alongside it.
08
Side by side
Free and paid features below were read from each app's App Store listing and official help pages.
| App | Free fasting timer | Meal logging | Body composition | GLP-1 logging | Coach |
|---|---|---|---|---|---|
| HAVIT | Fasting log free | Search logging free · AI Food Scan in Premium | Estimated (free) | Yes (free) | AI, reads every log · free chat has a daily limit |
| Zero | Yes | Photo logging in Zero Plus | Not listed | Not listed | No |
| Simple | Yes | Yes | No | In testing (iOS) | AI (Avo), limited free |
| BodyFast | Yes, 10+ plans | Not listed | Not listed | Not listed | Coach subscription |
| Fastic | Base app | Base app · scanner in Plus | Not listed | Not listed | AI chat in Plus |
| YAZIO | Built in · all plans in PRO | Yes · barcode in base feature list | Not listed | Not listed | Not listed |
App characteristics as of October 2026, from App Store listings and official help pages; HAVIT per its default settings. Plans change often — check the store listing before you subscribe.
09
Fasting without undoing it
Break the fast with protein.
The first meal decides whether the window did anything useful.
Keep the window you can repeat.
A 14-hour fast you keep beats an 18-hour fast you quit by Thursday.
Watch the trend, not the morning number.
Weight after a long fast is partly water.
Do not fast through warning signs.
Dizziness, fainting or a history of disordered eating are reasons to stop and speak to a clinician.
Some people should talk to a clinician before fasting at all
anyone who is pregnant or breastfeeding, under 18, has type 1 diabetes or is underweight.
On medication, ask first.
If you take a GLP-1, insulin or other glucose-lowering drug, work out a fasting plan with your prescriber.
On a GLP-1 with vomiting or diarrhea, fluids come before fasting.
Dehydration can lead to acute kidney injury, which is a warning on the drug labels.
For more on how fasting interacts with glucose, see fasting and metabolic switching with a CGM.
10
The bottom line
A fasting app that only times the window measures the easiest part.
Choose by what it sees after the timer stops: the meal that breaks the fast, the protein in it, and what is happening to your weight and body.
For a clean free timer, Zero or BodyFast. For calorie counting with a fasting timer, YAZIO. For fasting, meals, body composition and GLP-1 read together by one coach, HAVIT.
Frequently asked questions
What is the best free intermittent fasting app?
Does intermittent fasting work better than regular calorie cutting?
Can I do intermittent fasting while taking a GLP-1 like Wegovy or Zepbound/Mounjaro?
Does fasting cause muscle loss?
Why do fasting apps put most features behind a paywall?
What is HAVIT?
HAVIT is an AI health partner built on metabolic science — it protects your muscle, wakes up your metabolism, and helps you keep a healthy, rebound-free body for the long run.
Unlike calorie-only trackers, HAVIT connects AI body-composition estimates, nutrition, hydration, sleep, steps, cycle, mood, and GLP-1 medication in one daily routine — so progress is measured by body composition, not just the number on the scale. Daily missions turn established behavior-change techniques into small repeatable actions, drawing on expertise from professionals formerly at Juvis Diet, one of Korea’s leading metabolic clinics.
In HAVIT’s own analysis of 1,090 GLP-1 users, people who logged consistently built stronger habits than the general user base. Read the GLP-1 Habit Report
Inside the app
- AI COACHA coach that reads your day.
- NUTRITIONLog meals in seconds.
- BODY INSIGHTSSee more than weight.
- DAILY MISSIONSBuild habits you can repeat.
- DAILY CHECK-INTell HAVI how today feels.
- TRACK EVERYTHINGFrom water to GLP-1
- MIND & RECOVERYFor the days willpower runs out.
HAVIT works with or without GLP-1 medication. It is a wellness app, not a medical device; body-composition results are estimates.
Continue in the App
Personalized wellness with your own data
References
- Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters: The TREAT Randomized Clinical Trial (Lowe et al.) pubmed.ncbi.nlm.nih.gov
- Calorie Restriction with or without Time-Restricted Eating in Weight Loss (Liu et al.) pubmed.ncbi.nlm.nih.gov
- Zero: Fasting & Food Tracker (App Store) apps.apple.com
- Meet the new Zero Plus zerolongevity.com
- Subscription plans with Simple help.simple.life
- GLP-1 Companion help.simple.life
- BodyFast: Intermittent Fasting (App Store) apps.apple.com
- Fastic — creator page fastic.com
- YAZIO (App Store) apps.apple.com
- How does Yazio Pro support my goals? help.yazio.com
