Physiological responses to nutritional and reproductive constraints were explored in a wild population of Eurasian badgers (Meles meles) inhabiting Wytham Woods, Oxfordshire, United Kingdom. We compared seasonal blood levels of lipid and protein compounds to variables describing the sex, age, body condition, wounds, testes position, and flea abundance of the badgers. We found seasonal variations in albumin/globulins and urea/creatinine ratios matched by differences in body condition. High creatinine, urea, and triglycerides levels were obtained in animals in poor nutritional condition and with low levels of body fat. The maintenance of urea/creatinine ratios indicates that the badger does not demonstrate a stage of protein conservation in periods of food scarcity during the summer or periods of cold weather. Hypercholesterolaemia, especially in fat animals, was confirmed. We also offer baseline levels of metabolites commonly used in clinical biochemistry for their further use in the analysis of the status and the management of wild badger populations.