# Function Health vs Zest

The clearest difference is monetization model: Zest at free against Function Health's subscription. Function Health's advantage is ratings volume (25K vs 1) and update cadence (weekly vs every 3 weeks). On price, rating, ads and in-app purchases there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

On the App Store both sit at effectively the same score — 4.9 for Function Health against 5.0 for Zest. That said, the two scores are not equally well evidenced: Function Health has 25K ratings behind it against 1, so its average is the more settled of the two.

Function Health ships an update weekly, Zest every 3 weeks. The most recent releases landed on September 27, 2026 and September 8, 2026 respectively.

## The numbers

| Metric | Function Health | Zest |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [4.9 (25K ratings)](https://appshunter.io/ios/app/function-health/id6471280307/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/zest-longevity/id6639614937/reviews)** |
| Number of ratings | **25K** | 1 |
| Positive reviews | 61.9% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Weekly** | Every 3 weeks |
| Monetization | Subscription | **Free** |
| Size | 201 MB | 23 MB |
| Requires iOS | 16.4 | **16** |
| Devices | iPhone | **iPhone, iPod** |
| Age rating | 17+ | 17+ |
| Developer | [Function Health](https://appshunter.io/developer/1715014524) | [Zest Longevity LTD](https://appshunter.io/developer/1657646407) |

## What reviewers say

### Function Health

[App page](https://appshunter.io/ios/app/function-health/id6471280307)

Take control of your health with comprehensive lab testing, personalized protocols, and AI-powered insights. Understand your body's data, track changes over time, and make informed decisions for long-term wellness. Connect wearables and upload records for a complete health picture.

**Highlights:** 160+ lab tests annually, Personalized health protocols, Private AI Chat for results, Connect health wearables, Advanced MRI & CT scans, Upload health records

**Features:** Apple Wallet

**In-app purchases:** none

**What reviewers like**

- 🚀 Seamless process for blood tests and results
- 📊 Comprehensive health insights and tracking
- 🧠 Helpful clinician notes and recommendations
- 👍 User-friendly and visually appealing app
- 💰 Affordable compared to other options

**What reviewers complain about**

- 🔍 Lack of communication and support responsiveness
- 🐛 Some bugs and usability issues in the app

**Reported bugs**

- App sometimes redirects back to the home screen when trying to view results
- Occasional typos and formatting issues in the app

**Requested features**

- More customization options in the app settings
- Ability to print or export test results and recommendations
- Specific supplement recommendations rather than broad suggestions


### Zest

[App page](https://appshunter.io/ios/app/zest-longevity/id6639614937)

Discover your body's internal age and receive personalized insights to slow your aging rate. This app uses at-home tests and machine learning to analyze health metrics like cardiovascular fitness and cognitive function, providing tailored recommendations for improvement.

**Highlights:** Measure Functional Age, At-home health testing, Personalized health insights, Machine learning analysis, Tailored recommendations, Track aging metrics

**In-app purchases:** none


## Frequently asked questions

### Is Function Health free?

Function Health is free to download, with no in-app purchases.

### Is Zest free?

Zest is free to download, with no in-app purchases.

### Which has better reviews, Function Health or Zest?

Zest is rated higher. Function Health averages 4.9 out of 5 from 25K ratings, while Zest averages 5.0 from 1 ratings.

### Do Function Health or Zest have ads?

Neither Function Health nor Zest shows ads.

### Which is updated more often, Function Health or Zest?

Function Health ships an update weekly, and Zest every 3 weeks. Most recently, Function Health was updated on September 27, 2026 and Zest on September 8, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*