A science-backed, practical guide to fueling and hydration for Ironman and 70.3 triathlons. Covers carbohydrate, fluid, and electrolyte needs; bike and run fueling plans for different finish times; gut-training protocols; race-day routines, transition tips, and troubleshooting to avoid bonking, dehydration, cramps, and GI issues. Includes evidence-based guidance on supplements (caffeine, creatine, nitrates, beta-alanine) and step-by-step tools, formulas, and strategies for race-day performance.