INTRODUCTION: Improving the dietary behaviors of personnel can result in positive impact beyond the individual, creating benefits for their organization and wider society. Military personnel endure extended periods of physical and cognitive activity. Healthful dietary behaviors by military personnel support preparedness; yet poor diet behaviors remain common and persistent, and adversely impact health and physical and cognitive performance. Urgent and effective action is needed to improve diet behaviors, but this action has not been prioritized. This study aimed to estimate the value that could be realized from improved diet behaviors to support prioritization of investment in this area for policy and program change. MATERIALS AND METHODS: Value estimations (via Social Return on Investment methods) were performed to determine the potential financial benefit derived from improved diet behaviors for 2 military organizations: Australia and the UK. Estimations focused on benefits of reduced attrition and separation, improved productivity, mitigation of musculoskeletal injury (MSKI) risk, and reduced medical claims. RESULTS: The value of 5 outcomes was estimated for Australia and 3 for the UK. Conservative estimates were of the order of ∼£30 million in the UK (MSKI alone) and ∼$24 million in Australia. These are not insignificant sums of money and could deliver more when invested in health and performance compared with how far they would go toward alleviating attrition, productivity losses, and MSKI. CONCLUSION: These estimates were constructed using the best available data and transparency within the calculations, but they remain estimates. The collection of additional data would enable the calculation of further outcomes and increase the usefulness of Social Return on Investment estimation in this area. Militaries should invest greater effort and funding in achieving, maintaining, and optimizing personnel health and performance. Promoting healthy diet behaviors should be prioritized as a cost-effective preventive action that supports productivity and performance, in comparison with the costs of remediating treatment. Conceptualizing the value of improving diet behaviors in monetary terms may refocus efforts on prevention rather than treatment.