The Rysflo device on its charging dock, status light lit

Founding release

The device, the app, and a plan that changes every morning

$49per month, for twelve months

Device included, nothing upfront. Twelve monthly payments, then the device is yours to keep. $29 a month with a gym or trainer code.

Get Rysflo
What it measures

Three gases from one exhale. Acetone tracks whether you are drawing on stored fat, hydrogen shows whether a meal was absorbed or fermented, and ethanol shows whether sugar is being fermented by gut microbes. Each is scored against your own baseline, not a population average. The same three signals are read differently depending on your goal — fat loss or muscle gain.

How a reading is taken

Sixty seconds, fasted, before coffee. The app guides the inhale, the hold and a single controlled exhale. Standardised conditions — a ventilated room, a full warm-up — are part of the method rather than optional extras.

What is in the box
  • The device — three MEMS sensors in a brushed aluminium body, factory-calibrated
  • USB-C cable — charges in under an hour, a charge lasts about three weeks
  • Mouthpieces — a starter set, dishwasher safe
  • The app — iOS and Android
The twelve-month term

$49 a month for twelve months — $29 with a gym or trainer code — then the device is yours to keep. Nothing is charged upfront for hardware. Within the first 30 days you can return it for a full refund and the term ends there.

Specifications
  • Sensing MEMS metal-oxide array, three analytes separated by pattern recognition across the array
  • Calibration Factory-calibrated for five years, with a periodic self-check for humidity and baseline drift
  • Consumables Dishwasher-safe mouthpieces. No strips, cartridges or reagents
  • Connectivity Bluetooth 5.0 and USB-C. iOS and Android
Taking a morning breath reading at home with the Rysflo device

Everything included

  • The deviceThree-sensor breath reader. Yours outright once the twelve months are paid.
  • AI meal plansProtein, carbohydrate, fat and fibre in grams, rebuilt from each morning’s test. A deficit day might read 142 g protein, 178 g carbohydrate, 61 g fat, 34 g fibre.
  • Habit trackerDaily streaks, completion rate and the trend over time.
  • Share with your trainerA live view of your readings for a trainer or clinician. Revoke any time.
  • Weight and progressWeigh-ins read against your metabolism score, not on their own.
A man on the edge of the bed lacing his trainers before the day starts

How it works

  1. Subscribe$49 a month for twelve months, device included — $29 with a gym or trainer code. Nothing upfront, and the device is yours to keep at the end of the term.
  2. Breathe each morningSixty seconds before coffee. The app guides the inhale, the hold and one controlled exhale.
  3. Get the day’s planProtein, carbohydrate, fat and fibre in grams, rebuilt from that morning’s reading and your goal.
  4. Keep the streakEvery reading takes 20¢ off next month, up to $6.
A runner at full effort, mid-stride and motion-blurred
Effort is not the variable. Measurement is.

What goes wrong without a reading

Four failures that look identical on a scale.

01The switch never happens

A disciplined week can end with the body still running on the last meal rather than on its reserves.

02The loss is lean tissue

Weight comes off, but from muscle rather than fat. The number moves and the outcome is worse.

03The food is not absorbed

Meals that ferment rather than absorb. The plan is followed and the nutrition still does not land.

04You find out two weeks late

A weekly weigh-in reports the outcome long after the plan stopped working, and cannot say why.

A morning, start to finish

The whole routine is one minute and four screens.

A quiet kitchen first thing in the morning, before coffee06:40
Before anything elseFasted, before coffee. The overnight gap is what makes the reading comparable day to day.
A woman exhaling into the Rysflo device with the app open on her phone06:41
One controlled exhaleThe app guides the inhale, the hold and the breath out. Sixty seconds, start to finish.
The day's macro targets in the Rysflo app: carbs, fats, protein and fibre in grams06:42
The day’s numbersProtein, carbohydrate, fat and fibre in grams, derived from what the three signals said.
A protein and vegetable bowl portioned to the day’s macro targetsAll day
Eat to themLog a meal the way you would say it. The plan updates against what you have already had.

The number moves because you changed something

Not because you weighed yourself at a different hour, or drank less water, or caught a good night’s sleep. A breath reading answers to what your metabolism did, and nothing else.

It pays to be regular

The measurement only works if you take it, so the price follows the habit. Drag across the month below and watch what you would pay.

A month of mornings

Tap a day, or drag across several.

$49.00 a month

Tap the days you would actually test and the price follows.

Readings you take this month set next month’s price. Miss a day and nothing is lost — you simply earn less that month, and the next one starts fresh. A reading earns 20¢ whatever the month, up to $6 — and a month completed in full always earns the whole $6, February included.

How it compares

The three ways to find out what your metabolism is doing.

RysfloA wearableA lab metabolic test
What it measures Acetone, hydrogen and ethanol, directly Movement, heart rate, skin temperature — inferred Gas exchange, directly
How often Every morningContinuouslyOnce, if ever
Where At home, sixty secondsOn your wristA clinic appointment
What you do with it The day’s macros, in gramsActivity and sleep summariesA one-off resting rate
Cost $49 a month, or $29 with a gym or trainer code — device included $200–$500 upfront, plus subscription $100–$250 per test

Comparison figures for wearables and lab testing are typical US ranges, not quotes for a specific product.

The app in week one: a single fat-use reading on the dial
Week one · one reading
The app in week six: the run of readings drawn as a trend, held inside the recommended range
Week six · the trend

What six weeks looks like

One reading is a snapshot. The value is in the run of them — a trend that shows whether what you changed actually moved the signal, and by how much.

The app keeps every reading, scores each against your own baseline rather than a population average, and reads your weigh-ins against the metabolism score instead of on their own.

Questions before you buy

What happens at the end of the twelve months?

The device is yours to keep. The subscription covers the hardware over the term, so there is nothing to return and nothing further to pay for the device itself.

Can I cancel before twelve months?

Within the first 30 days, yes — return the device for a full refund and the term ends there. After that the twelve monthly payments are a commitment, because the hardware is included at no upfront cost.

How does the discount work?

Every reading you take takes 20¢ off the following month, up to $6. Complete a whole month and you earn the full $6 whatever the month’s length — February included — so that month is charged at $23 instead of $29. Do it every month and the twelve-month term costs $276 rather than $348. Miss a day and you simply earn less that month; nothing carries over as a penalty.

Do I need to buy anything else?

No. Mouthpieces are dishwasher safe and there are no strips, cartridges or reagents. The app is included on iOS and Android.

Can I use it alongside a GLP-1?

Yes. Rysflo does not interact with medication — it measures. On a GLP-1, where lean mass comes down alongside the fat, a daily reading of whether you are actually oxidising fat is the one it is most useful for.

Is my data shared with anyone?

Only with people you choose. You can give a trainer or clinician a live view of your readings and revoke it at any time, and you can export or delete your data whenever you want.