<h3>Background</h3> Cooperative Extension Services (CES) provides research-based information to communities. Rapidly changing trends leave communities seeking reliable information. There is a need to assess CES agents' knowledge about fad diets to develop effective professional trainings. <h3>Objective</h3> To assess general and potential adverse effects knowledge of fad diets of CES agents and factors influencing that knowledge. <h3>Study Design, Setting, Participants</h3> An online survey assessed CES agents employed in Louisiana, Texas, Mississippi, and Arkansas working in family and consumer science, nutrition, or related fields. The survey included demographic items, certifications held, years of experience, professional association memberships, education level and knowledge items to assess general and adverse effects knowledge of low-carbohydrate diets, intermittent fasting, detoxes, and cleanses. IRB approval was obtained from Louisiana Tech University. State office designates distributed the survey link to eligible agents. <h3>Measurable Outcome/Analysis</h3> Descriptive statistics characterized respondents. Knowledge items addressing diet premises and adverse effects were scored and categorized by diet type. ANOVA testing determined factors that influenced knowledge. <h3>Results</h3> Eligibility was met by 138 respondents. The most reported length of employment was 1-10 years (42%), and master's degrees for education level (63%). The mean score for total knowledge of fad diets was 70%. Respondents scored higher for general knowledge (75%) than adverse effects questions (65%). Members of the Society for Nutrition Education and Behavior (SNEB) and the Academy of Nutrition and Dietetics (AND) scored highest for total knowledge (72%), as didRDN, DTR, and Certified Health Education Specialist (CHES) certifications (74%). An ANOVA yielded a significant effect for CHES certification, F (1, 2) = 5.16, <i>P</i> = .03 and for RDN/DTR certifications, F (1, 0) = 4.83, <i>P</i> = .03 for adverse effects knowledge. Respondents (80%) chose webinars as the preferred delivery method of professional education. <h3>Conclusions</h3> Findings can be used to create needed meaningful professional development for Family and Consumer Sciences agents.