The influence of a fuel-side heat loss zone on a diffusion flame established between fuel and oxidizer reservoirs is investigated using a model heat loss profile. The radiative heat loss suffered by a flame due to particulate soot served as the background motivation for this study. For each chosen flame, the intensity, width and location of the heat loss profile were parametrically varied to assess the sensitivity of the flame to heat losses. The influence of such variations on the heat release, the heat flux to the reservoir walls, the radiative fraction and the drop in flame temperature was studied. Emphasis was placed on the phenomenon of flame extinction due to increased heat losses. Extinction plots were generated for a range of fuel and oxidizer reservoir mass fraction values. The influence of the losses is characterized best by the integrated value of the heat loss profile. In all situations studied, the temperature and reactivity peaks moved toward the fuel side with increased heal losses.