Measure your
metabolism

Breathe into Rysflo to know what your body needs, and use that data to build lasting habits for weight loss, muscle gain, or simply better health. Measure what matters and live your best life without guessing.

Every morning, Rysflo answers

Am I burning fat?
Is my gut absorbing what I ate?
Is sugar fermenting in my gut?

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$29 / month AI meal plans HIPAA compliant

Why measure your metabolism

Two people can eat the same food and get different results. Metabolism differs between people, and it shifts day to day with sleep, stress and when you last ate. You cannot see it or feel it, and weight is a slow, noisy way to find out. Measuring it takes a minute.

How your metabolism works

Whatever we eat, our body either burns it or stores it. What it does with it shows up in our breath.

Digestion

Food is broken down into sugar and fat. What the gut absorbs goes into the blood. What it does not absorb travels on to the colon, where bacteria feed on it.

Metabolism

We run on the sugar from that meal, or on the fat we already have stored, switching between the two through the day. Every time we burn something, it leaves something behind.

Breath

Some of what we leave behind is small enough to pass out of the blood and into the lungs. So it turns up on the breath, in amounts that match what is in the blood. Rysflo reads three of them.

Most breath trackers read one signal.
Rysflo reads three

Acetone, hydrogen and ethanol — three biomarkers, read from one exhale.

C₃H₆O · Acetone

Fuel

Are you burning fat?

Our body produces acetone whenever we burn fat. It is light enough to leave through the lungs, so the more fat we burn, the more of it turns up on the breath.

H₂ · Hydrogen

Gut

Did your gut absorb the meal?

Food the gut does not absorb carries on to the colon, where bacteria feed on it and give off hydrogen. That hydrogen comes back out on the breath, which is how we know the meal did not land the way it should have.

C₂H₅OH · Ethanol

Fermentation

Is sugar fermenting in your gut?

Some gut microbes turn sugar into alcohol. A trace is normal; more on the breath after a meal means the sugar was fermented rather than absorbed.

From reading to guidance

A measurement is only useful if it changes a decision. These are the outputs Rysflo derives from the three signals.

This morning

78Strong

Acetone6.9 ppm

Hydrogen0.0 ppm

Ethanol6.0 ppm

Daily measurement

Sixty seconds before coffee. Three biomarkers, scored against your own baseline rather than a population average.

Weight

78.4kg

Down 2.1 kg over six weeks

Weight logging

Log it once a week and the app reads it against your breath data, so you can see whether the loss is coming from fat or from muscle.

Six-week trend

+24% fat oxidation

12 AM6 AM12 PM6 PM

Fat oxidation trending up

Trends that mean something

One reading is a snapshot. Six weeks of them shows whether what you changed actually worked.

Today’s targets

2,100kcal today

Protein165 g

Carbohydrate180 g

Fat80 g

Four numbers, set every morning

Protein, carbohydrate, fat and fibre in grams. The split is derived from three inputs: what the breath measured, the goal you set, and how far the current state still is from the target one.

Protein target

142g

68 g so far · 74 g to go

Targets that move with the reading

A fixed gram-per-kilo rule does not know what happened overnight. When acetone runs high the protein target rises to protect lean mass; when hydrogen spikes the fibre and carbohydrate sources change rather than the totals.

Logged

116g logged

Protein46 g

Carbohydrate52 g

Fat18 g

Food logging that is not a chore

Type it the way you would say it. No barcode hunting, no scrolling a database of nine hundred yoghurts.

This month

23day streak

Longest yet

Habits, not willpower

A streak you can see is the thing that survives a bad week. The device gives you one small action a day, and it takes a minute.

Fasting window

14:22

Rising since hour 12

Fasting, with evidence

Most fasting advice is a clock. Yours is a measurement — you can see the point where your body actually switched fuel, and when extending it stops paying.

Shared with

2people

TrainerActive

ClinicActive

Revoke any time

Share it with the people helping you

Give your trainer or clinician a live view of your readings, so their advice is based on what your body did this week rather than what you remember of it.

Your data

256bit encryption

Encrypted in transit✓

Encrypted at rest✓

Export or deleteAny time

On infrastructure that is tested

Health data on penetration-tested, HIPAA-aligned infrastructure. You choose who sees it, and you can withdraw that at any point or take your data out entirely.

The Rysflo app home screen: today's score, the streak, and the score history over the past week

Trends that show the direction

One reading is a snapshot. Six weeks of them show the direction — scored against your own baseline, not a population average.

The Rysflo app weight screen: current weight, target, and the weight chart over several weeks

The scale, read against your metabolism

Weight alone swings with water and last night’s dinner. Read against your metabolism score, a flat week tells you which it was.

The Rysflo app chat with Rys, the in-app AI chef, suggesting a snack that fits the calories and protein left for the day

Food that fits your numbers

Macros from your own readings, with a recipe for every meal and any brand you buy. Swap a meal, ask Rys for something that fits, or photograph the plate.

Backed by years of scientific research

Rysflo uses a metal-oxide sensor array to measure three gases in a single breath: acetone, hydrogen and ethanol. Each has been studied in clinical and metabolic research for decades — on benchtop analysers, in hospital and university labs.

Sixty seconds, one exhale

You breathe in, hold, and exhale once through the mouthpiece. The sample passes over the sensor array; the signals are separated by pattern recognition across the array rather than read off any single element.

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In use

Reports from trainers, clinicians and people taking a daily reading.

“I had done the same diet three times and quit it three times. Seeing the fat number move on a Tuesday is what made me keep going to Friday.”

Marissa T.Lost 14 lb in four months

**Derek L.**Personal trainer, Brownsville TX

**Sam K.**Training for a first half marathon

**Priya N.**Nurse practitioner, weight-loss clinic

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Questions people ask

How does this differ from a wearable?

A wrist device infers physiology from movement, heart rate and skin temperature. Rysflo measures metabolic by-products directly. The distinction matters because two people with identical activity data can be in entirely different metabolic states.

Why does the reading have to be in the morning?

Standardised sampling conditions reduce variance. A fasted morning reading removes the confounding effect of a recent meal, which shifts both acetone and hydrogen substantially. The overnight gap you already have is the only fast required.

Can I use it alongside a GLP-1?

Yes, and it is one of the clearest uses. Medication changes what you eat but not what your body does with it. Rysflo shows whether you are holding onto fat loss, and where protein and timing need to change — including through the transitions on and off treatment.

Is there a subscription?

The first year of guidance is included in the price. After that it renews annually, and you can cancel and keep using the raw readings.

Who should not use it?

Rysflo is a wellness device, not a diagnostic one, and it does not diagnose or treat any condition. If you are pregnant, under 16, or managing diabetes or liver disease, speak to your clinician before changing anything based on a reading.