The purpose of the study is to investigate the temperature profile of fat tissue during neodymium-doped yttrium aluminum garnet laser irradiation (1064, 1320, and 1444 nm wavelengths) for laser-assisted lipolysis. The numerical analysis was performed to assess the wavelength dependence of the temperature distribution in fat tissue. For the internal temperature profile measurements, a cannula was placed in the middle of fat tissue for laser irradiation, and two hypodermic thermocouple needles were placed at 2 and 5 mm apart from the cannula. For surface temperature measurements, an infrared camera was placed at the surface of fat tissue. The highest temperature with the least thermal expansion in fat tissue was observed in the 1444 nm wavelength both on the numerical analysis and on the experimental results. Therefore, the 1444 nm wavelength provided the highest thermal confinement with the least thermal damage in surrounding tissue as compared with the other two laser wavelengths, 1064 and 1320 nm.