With the awareness that the Standard American Diet is a critical contributor to chronic diseases, this initiative aimed to assess the effects of a 28-day dietary challenge health care improvement project on health system employee energy level, sleep quality, gastrointestinal function, ability to concentrate, and aches/pains, including the impact of adherence level, during a period of restricted intake of gluten, dairy, and sugar offered annually from 2021 to 2023. A total of 754 employees completed the pre-challenge survey; analyses included 354 employees who completed both pre-challenge and post-challenge surveys in at least 1 year of this project. Wilcoxon signed rank tests compared presurvey and postsurvey responses to self-reported energy level, sleep quality, gastrointestinal function, ability to concentrate, and aches/pains. Analysis of variance with Tukey's honestly significant difference tests compared self-reported adherence level with change scores, with η representing effect size. In each challenge year, the mean rank levels of energy, sleep quality, gastrointestinal function, concentration, and aches/pains improved significantly between pre-surveys and post-surveys (all <.001). Although an association between significant positive change and diet adherence level was found for all items in at least 1 challenge year, those who mostly or completely adhered to the challenge diet restrictions reported significantly greater positive change in energy levels and gastrointestinal symptoms than those who did not or minimally adhered in all challenge years, with small to medium effect sizes. In conclusion, Essentia Health's employee challenge appeared to improve self-reported outcomes in 5 symptom domains, with energy levels and gastrointestinal symptoms correlating most favorably to adherence to the challenge. These findings have health and cost implications, which could be confirmed by formal research in employee and other populations.