Abstract Studies on the ratios of stable isotopes of carbon and nitrogen constitute a research tool commonly applied in bioarchaeology to reconstruct human diets, including the origins of proteins consumed, the relationship between plant and animal foods, weaning processes, and parameters of the environment from which the food was obtained. Within the comprehensive analysis of the excavation results carried out at site 3 in Miechów (approximately 30 km north of Kraków), isotope analyses of δ13C and δ15N were performed on the human groups that inhabited the site from the Neolithic to the Iron Age. In total, 41 skeletons were investigated. The analyses aimed to hypothesise the nutritional strategies of communities of successive periods and to compare the knowledge obtained with current data and interpretations on food management in prehistoric communities of Central Europe. The results indicate a general predominance of a terrestrial diet, with plant-based foods prevailing, although not conspicuously. However, there are indications of slightly varying nutritional strategies among successive human groups. These differences are related to the contribution of animal protein and the relationship between C3 and C4 plants. For instance, in the Middle Neolithic (4th millennium BC), a greater consumption of meat and/or cereals from manured fields can be postulated compared to the Early Neolithic (late 6th and 5th millennia BC). On the other hand, the proportion of meat in the diet of Early Bronze Age inhabitants (2nd millennium BC) was possibly the lowest in the entire history of site occupation. This proportion returned to near-Neolithic levels in the developed Bronze Age and Iron Age (1st millennium BC). Regarding plant food, the results indicate greater variability in the plants consumed in the Bronze and Iron Ages. Levels of δ13C imply some contribution from C4 plants, that is, millet, during these periods. This aligns with recently formulated theories suggesting the post-Neolithic beginnings of millet cultivation and consumption in Central Europe.