Natural carbon isotopes, $^{12}C$, $^{13}C$, and $^{14}C$, help to authenticate/trace foods and beverages. Levels of total carbon (TC), $^{13}C$ (${delta}^{13}C$), and $^{14}C$ in muscle and lipid tissues from grass-fed versus grain-fed steers are reported. The ${delta}^{13}C$ in muscle versus lipid of steaks were around 5‰ higher in grain over grass-fed (p<0.05). The ${delta}^{13}C$ and $^{14}C$ levels were higher in muscle over lipid tissues while the opposite was true for TC (p<0.05). TC content was around 20% higher in lipid over muscle due to different elemental compositions, lipid versus muscle, not carbon isotopes discrimination.