Physiological Reaction After Food Intake

The aim of this study is to investigate physiologically measurable reactions of the body to food intake. We want to find out which of the parameters collected can provide information about food intake and which techniques for data collection are expedient in this context. Ultimately, the aim is to develop a way of determining food intake from physiological data from physiological data without the user indicating this to the device.

The following data is collected continuously over a period of 2 weeks: Electrocardiogram (ECG), pulse rate from photoplethysmogram, body temperature, movement, skin conductance, and a continuous glucose measurement in the interstitium (CGM). The test subjects will also be asked to document each of their meals and snacks via an app using a photo. As an optional additional examination, female study participants will be offered an intravaginal temperature measurement. This independently performed measurement enables the core body temperature to be recorded.

• Wearable (Device): Participants will wear an electrode on the chest for the measurement of the heart rate variability, a sensor for temperature measurement, and a sensor for continuous blood glucose measurement. Food intake will be recorded via pictures. One mixed meal tolerance test will be performed as a reference for further analyses. Females have the option to use a device for intravaginal temperature measurement.

Primary outcomes

• Electrocardiogram [2 weeks]: Changes in heart rate variability in response to food intake. Assessed through Vivalink ECG wearable that measures a continuous 3-channel ECG.
• Body temperature [2 weeks]: Changes in body temperature in response to food intake. Vivalink ECG and CORE sensor continuously measure the skin temperature. CORE sensor is also able to determine the body core temperature via a heat flux sensor. For women, body core temperature can be measured with the trackle wearable.
• Skin conductance [2 weeks]: Changes in skin conductance in response to food intake. CardioWatch wearable continuously measures the skin conductance
• Glucose level [2 weeks]: Changes in glucose levels in the interstitium in response to food intake. FreeStyle libre sensors continuously measure the glucose levels.

Secondary outcomes

• Physical Activity [2 weeks]: The wearable Vivalink ECG contains an accelerometer to continuously assess activity, intensity and body position.
• Food intake [2 weeks]: Assessed through photo-documentation of consumed food

Other outcomes

• Correlation of physiological measures (electrocardiogram, pulserate, body temperature, skin conductance, glucose level) [2 weeks]: Correlation of the obtained physiological measures (electrocardiogram, pulserate, body temperature, skin conductance, glucose level) among each other and with food quantity and quality will be assessed
• Sex differences [2 weeks]: Differences in the obtained physiological measures between sexes will be analyzed.
• Correlation with glycemic and insulin sensitivity [2 weeks]: Correlation of the obtained physiological measures among with glycemic, lipidemia, and insulin sensitivity will be analyzed.

Sex: All, ages: 18 Years to 30 Years, accepts healthy volunteers

Inclusion Criteria:

* BMI 18.5 - 25 kg/m2

Exclusion Criteria:

* vegan diet
* any kind of special diet, e.g. to lose weight
* use of medication, except for thyroid hormones and contraceptives

• Martin Heni, MD, Principal investigator, University of Ulm