Folsom, Calif., (Dec. 1, 2015) - A new study published in the Journal of Nutrition found that one serving of walnuts (1oz) may provide 146 calories, which is 39 calories less, or 21 percent fewer, than the 185 calories listed in the USDA Nutrient Database. (1) The study takes into account the digestibility of walnut pieces and halves, and further research is needed to better understand the results of the study and how this technique for calculating calories could potentially affect the calorie count of other foods. The research was led by Dr. David J. Baer, PhD, Supervisory Research Physiologist at the Agricultural Research Service, United States Department of Agriculture (USDA).