Introduction Nutritional balance is among the major concerns of modern people, as it is known that diet directly impacts the overall state of the human body. To choose the optimal diet for everyone, a personalized approach is needed. The purpose of this study was to validate a sensor for food impact assessment by analyzing the levels of volatile organic compounds (VOCs) in human breath. It aims to establish a prototype for future auxiliary technique for nutritional status clarification. Breath research has been very popular in the last 10 years, mainly due to its non-invasive diagnostic potential. As the proposed sensor does not require laboratory conditions, its application could be widespread due to fast analysis, portability, and affordability. Methods This pilot study recruited various groups of participants from several European countries, with informed consents and ethical approvals. The groups included overweight participants, those with obesity, and those who have poor dietary habits. Food impact assessment was conducted by monitoring levels of several VOCs related to macronutrients metabolism in exhaled breath samples using the new portable sensor based on membrane inlet mass spectrometry (MIMS). Each participant provided a sample before standardized meal (after 12h food restraint) and 120 min after the meal. Also, information about participants’ lifestyle was collected via a short questionnaire. Samples were collected in 1L single-use Tedlar ® bags and analyzed using the MIMS system with PDMS sheet membrane probe. Preliminary Data Functionality of the new portable breath VOC sensor was verified by examining several analytical parameters in our preliminary research study on a group of healthy participants (not published yet). That pre-pilot study showed that the examined MIMS system could be used successfully for breath VOCs analysis, and for monitoring the changes in VOCs levels upon food consumption. A large-scale pilot study employing the new method on more population groups was the natural continuation of the pre-pilot study. Concentration levels for selected breath VOCs (acetone, ethanol, isoprene and n-pentane) were determined in samples before the meal (BM) and after the meal (AM). Additionally, qualitative and quantitative aspects of food impact assessment were determined and evaluated. The qualitative assessment provided information about whether a specific breath VOC increased or decreased as a consequence of food ingestion. Furthermore, quantification of the food impact was established via comparison factor. This factor represents the ratio of VOC levels after and before the meal, i.e., AM/BM for the same participant. Comparison factor served to express the intensity of the change in VOCs signal. More than 10% of signal increment or decrement was considered as food impact. Additionally, the experimentally obtained results were examined against the data collected via the questionnaire in order to discover possible correlations between VOCs changes and specific population group or their lifestyle habits. The results obtained in this pilot study support the fact that proposed VOC sensor can be utilized in breath research and contribute to the enrichment of the breath research area. Novel Aspect Portable MIMS sensor for detection of VOCs showed potential to become fast screening methodology for nutritional status diagnostics.