Baumeister, R. F., & Toerney, J. (2011). Willpower: Rediscovering the greatest human strength. New York: Penguin Group.

While artificial sweeteners stimulate the taste buds, they also affect the brain. Aspartame, for example can reduce the production of dopamine. Humphries, P., Pretorius, E. & Naudé, H. (2008). Direct and indirect cellular effects of aspartame on the brain. European Journal of Clinical Nutrition, 62(4), 451-462. doi: 10.1038/sj.ejcn.1602866). The lack of a nutrient reward when saccharin is tasted results in reduced dopamine surges after conditioning. Mark, G. P., Blander, D. S., & Hoebel, B. G. (1991). A conditioned stimulus decreases extracellular dopamine in the nucleus accumbens after the development of a learned taste aversion. Brain Research, 551(1), 308-310. doi: 10.1016/0006-8993(91)90946-S). Like the artificial sweeteners, stevia is nonnutritive and may cause long-term depressed levels of dopamine.