The molecular and isotopic chemistry of organic residues from archaeological potsherds was used to obtain further insight into the dietary trends and economies at the Constance lake-shore Neolithic settlements. The archaeological organic residues from the Early Late Neolithic (3922–3902 BC) site Hornstaad-Hörnle IA/Germany are, at present, the oldest archaeological samples analysed at the Institute of Mineralogy and Geochemistry of the University of Lausanne. The approach includes ¹³C/¹²C and ¹⁵N/¹⁴N ratios of the bulk organic residues, fatty acids distribution and ¹³C/¹²C ratios of individual fatty acids. The results are compared with those obtained from the over 500 years younger Neolithic (3384–3370 BC) settlement of Arbon Bleiche 3/Switzerland and with samples of modern vegetable oils and fat of animals that have been fed exclusively on C₃ forage grasses. The overall fatty acid composition (C₉ to C₂₄ range, maximizing at C₁₄ and C₁₆), the bulk ¹³C/¹²C and ¹⁵N/¹⁴N ratios (δ¹³C, δ¹⁵N) and the ¹³C/¹²C ratios of palmitic (C_16:0), stearic (C_18:0) and oleic acids (C_18:1) of the organic residues indicate that most of the studied samples (25 from 47 samples and 5 from 41 in the δ¹³C_18:0 vs. δ¹³C_16:0 and δ¹³C_18:0 vs. δ¹³C_18:1 diagrams, respectively) from Hornstaad-Hörnle IA and Arbon Bleiche 3 sherds contain fat residues of pre-industrial ruminant milk, and young suckling calf/lamb adipose. These data provide direct proof of milk and meat (mainly from young suckling calves) consumption and farming practices for a sustainable dairying in Neolithic villages in central Europe around 4000 BC.