High-intensity functional training (HIFT) has grown in popularity in the past several decades, yet previous research has largely focused on the dietary habits and body composition of elite HIFT athletes and utilized only quantitative study designs, potentially limiting our understanding of typical HIFT athletes. This study aimed to comprehensively describe the common dietary habits and body composition of HIFT athletes. Data were only analyzed descriptively. Among 62 HIFT athletes (age: 36 ± 11.7 years), we estimated body fat percentage (BF%) using a Siri 3-compartment model, and we assessed dietary habits, dietary supplement (DS) use, and open-response rationales for DS use/disuse via an online questionnaire. Qualitative data from open-response questions were coded and grouped via inductive thematic analysis. Body composition varied among both male (n = 36, BF% = 6.5–27.6%) and female participants (n = 26, BF% = 10.6–37.6%). Most participants reported regular consumption of lean meats and home-cooked meals, yet few participants (~20%) regularly consumed the recommended twice daily servings of dairy, fruits, vegetables, and whole grains. Most (77.4%) HIFT athletes reported DS use, with the average HIFT athlete using approximately six DS; dairy protein, creatine, caffeine, and electrolyte drinks were the most reported DS. Improving health, recovery, and nutrient intake were common reasons for using DS, whereas a lack of noticeable results was the most common reason for discontinuation. Some HIFT athletes may rely on DS to address nutrient gaps rather than whole foods.

Research designed to reduce or eliminate fishmeal (FM) in trout feeds, for reasons that have changed over time, has been conducted for over a century. Reducing the dependency on FM remains one of the most urgent issues facing the industry. Feed represents the most expensive operational cost of fed aquaculture, and is responsible for ecosystem disturbance following nutrient discharges. Rainbow trout, the second most farmed salmonid globally, can be raised completely without FM or fish oil (FO), with its growth and efficiency not differing from trout fed FM-based feeds. However, ingredient choice and nutrient supplementation strongly influence physiological responses, efficiency, and long-term outcomes. As land animal proteins are increasingly used in place of FM, both with and void of dietary FO, their distinct biological effects warrant focused evaluation. Although numerous studies have synthesized findings across various alternative protein categories including those with insect proteins and animal by-products, this literature is widely disseminated and sometimes difficult to access. The present contribution focuses on terrestrial/aerial animal proteins that have been used to totally replace FM in rainbow trout feeds. Attention is given to their effects on physiological control processes that may influence production efficiency. Areas worthy of future study are identified and include long-term performance and health dynamics, the refinement of nutritional and formulation strategies, and the broader evaluation of biological interactions and system-level outcomes.