Few controlled feeding experiments have investigated the degree to which dietary lipids contribute carbon to structural tissues and influence isotopic signatures, and most studies have focused on soft tissues. This study utilizes a rodent model to examine the effects of a ketogenic diet (high fat, low carbohydrate) on the δ13C values derived from bone tissue (bone collagen and bone apatite). Femora were opportunistically harvested upon conclusion of an unrelated study, where adult rats had received either ketogenic diet (KD) or a micronutrient, protein, and calorie-matched standard diet (SD) for 6 months. Bone samples were prepared for stable isotope ratio analysis and δ13Ccollagen, δ15Ncollagen, δ13Capatite, and Δ13Capatite−collagen values were determined. Observed differences in δ13Ccollagen values between KD and SD groups indicate significant assimilation of lipid-derived carbon among the KD animals. KD-fed rats recorded lower δ13Capatite values and smaller Δ13Capatite−collagen values than those fed the SD, reflecting the respective dietary energy macronutrient profiles. Incomplete equilibration with the experimental diets precluded determination of Δ13Capatite−diet values, and possible group differences in isotopic discrimination associated with the metabolic shift from glycolysis to ketosis among the KD rats could not be evaluated. Experimental outcomes highlight the influence of dietary lipids on metabolic routing and suggest that sampling bone collagen alone could lead to inaccurate dietary interpretations among past human populations where access to carbohydrates was limited and lipids supplied the majority of daily energy needs. Implications for stable isotope analysis (SIA) and dietary reconstruction studies based on archaeological and neontological materials are discussed.