New Device Measures Fat Burning Through Single Breath Analysis

A team at the Swiss Federal Institute of Technology in Zurich (ETH Zurich) has developed a device that detects fat burning by analyzing acetone levels in a single breath. Acetone is naturally produced when the body switches to using fat instead of carbohydrates for energy, whether during exercise, dieting, or fasting.

The device resembles the breathalyzers used by police for alcohol detection but is designed to measure metabolic indicators. Users blow into the device, which connects to a smartphone app via Bluetooth. The app analyzes the breath sample and displays results in about 90 seconds.

Researchers explained that the main challenge was separating acetone molecules from the abundant water vapor in exhaled air, as humidity can affect measurement accuracy. To address this, the device includes a chemical filter that absorbs acetone and blocks moisture interference, along with a smart system that guides users during exhalation to ensure correct sample collection.

Accuracy Comparable to Laboratory Equipment

The device underwent testing with 12 volunteers, collecting over 300 breath samples under various conditions, including exercise and different diets. Results showed that its readings closely matched those from mass spectrometry devices used in laboratories, with a margin of error around 7.5 percent in some measurements. Researchers deemed this precision sufficient for monitoring changes in fat burning.

Andreas Guntner, a professor of molecular sensing at ETH Zurich and head of the research team, stated that the device aims to make metabolic monitoring as simple as measuring weight or blood sugar. He noted that individual responses to exercise or diets vary, making personalized monitoring more beneficial than relying on general guidelines.

How Acetone Reflects Fat Metabolism

When carbohydrate stores in the body decrease, the liver breaks down fats to produce energy, generating ketone bodies including acetone. This acetone travels through the bloodstream to the lungs and is exhaled. Therefore, measuring acetone provides a direct indicator of whether the body is using fat as an energy source. In contrast, most current smartwatches estimate this indirectly through heart rate or physical activity levels.

Applications Beyond Weight Loss

The researchers foresee the device’s use extending beyond weight loss to monitoring patients on therapeutic diets, such as those with epilepsy following ketogenic diets, as well as individuals with diabetes and metabolic disorders. Athletes aiming to optimize their bodies’ energy utilization may also benefit.

Additionally, the device could assist in assessing patient responses to new anti-obesity treatments, including medications based on the GLP-1 hormone, by tracking real-time changes in fat burning.

Future Availability and Clinical Validation

Despite promising results, researchers emphasize that broader clinical studies involving diverse age and health groups are still needed before the device can be adopted as a diagnostic tool in medical practice. The technology has been commercialized through a startup originating from the Swiss institute, but developers stress that the current version is intended for metabolic monitoring only and does not replace medical evaluations or established clinical tests.

This innovation reflects a growing trend toward personal health devices that provide immediate data to users. Researchers aim to shift vital sign monitoring from laboratories into everyday life, enabling individuals to better understand their body’s responses to food and exercise and make more precise health decisions.