Childhood obesity has reached epidemic levels, yet many health professionals lack confidence in working with parents around lifestyle change. HENRY (Health Exercise Nutrition for the Really Young) aims to tackle this through training practitioners to work more effectively with parents of preschoolers around obesity and lifestyle issues.We evaluated the long-term impact of HENRY training on health professionals' knowledge, skills and confidence in tackling obesity prevention. All practitioners trained 2007-11 (n = 1601) were invited to complete an online survey. 237 emails (14.8%) were undeliverable; 354 (26.0%) of the remainder completed the survey. A majority (67%) reported using knowledge and skills gained on a regular basis in their professional lives. Sessions on the importance of empathy and key parenting skills were considered particularly useful, with 78% and 74% respectively reporting regular use of these skills. Effects on respondents' personal lives were also reported: 61% applied the knowledge and skills at home, identifying for example, more shared family mealtimes and reduced portion sizes. The impact endures, with 71% of those undergoing training > 12 months ago, stating that they continued to use concepts in their professional lives. The findings suggest that brief training can have a sustained impact on practitioners' professional and personal lives.