With substance use disorder rates rising, there is an urgent need for new and effective treatment modalities. The utilization of nutrition services in addiction treatment has not been standardized, but there is a growing trend towards incorporating registered dietitian nutritionists into the treatment team. This comprehensive overview explores the impact of alcohol, cocaine, methamphetamine, and opioids on nutritional status. This presentation places particular emphasis on gut health, microbiome, and associated neural interactions. Homeostatic and hedonic mechanisms of eating behavior are discussed in the context of eating disorders and food addiction. Given the current crisis of addictive disorders, consideration should be given to prioritizing efforts to improve eating habits and overall health in recovery programs. Guidelines for nutrition interventions will be proposed, and a summary of where more information is needed will point towards future directions.