Wan Xin and his colleagues started their soldier nutrition research at the end of 1938 when the War of Resistance against Japanese Aggression was at the stage of stalemate. They followed this work up with the establishment of the Nutrition Research Institute at the Military Medical College. The urgent requirement at that time was to ensure and improve dietary nutrition of soldiers during the war because most soldiers were short of basic nutrition, the nonbattle injury casualty rate among the soldiers at the front was high and wounded soldiers recovered slowly in the Army hospitals. Wan Xin and his colleagues conducted investigations among wounded soldiers on their physical and nutritional status at the front and at military hospitals. They proposed a series of practical solutions to protect the strength of soldiers. In addition, their research on wartime nutrition security issues met the requirements of the war and promoted the establishment of modern nutrition science in China and the development of academic communities.
1938年底，抗日战争进入漫长的相持阶段，由于最基本的营养需求得不到满足，出现了前方士兵严重的非战斗减员以及军医院中伤病士兵战力恢复缓慢等问题。此后，保障并改善战时士兵的膳食营养状况成为持久抗战的紧迫需求。万昕等一批营养学家由此开始了战时士兵的营养保障工作，军医学校营养研究所也正是在这样的情况下建立起来的。在深入调查、科学分析的基础上，万昕和同仁根据当时的条件因陋就简、就地取材，针对战地士兵战力保障和军医院士兵战力恢复，提出了一系列切实可行的解决方案，并取得了良好效果。此外，他们面对战时营养保障问题所展开的研究，在回应了战场需求的同时，也形成了独具特色的学理成果，相关工作直接推动了现代营养学在中国的建制化和学术共同体的形成。.