Certain populations require specific nutritional considerations. The Female Athlete Triad consists of three interrelated conditions: low energy availability (with or without disordered eating), menstrual dysfunction (amenorrhea), and low bone mineral density (osteoporosis). This is now part of the broader concept of Relative Energy Deficiency in Sport (RED-S), which describes impaired physiological function caused by low energy availability affecting both males and females, with impacts on metabolism, menstrual function, bone health, immunity, protein synthesis, cardiovascular health, and psychological well-being. Masters athletes (over 40) need higher protein intake (1.6–2.2 g/kg/day) due to anabolic resistance, along with adequate vitamin D, calcium, omega-3s, and possibly creatine supplementation, with longer recovery times making post-workout nutrition timing more important.
Athletes in weight-class sports should minimize weight-cutting and compete as close to their natural weight as possible; if cutting is necessary, weight should be lost gradually at 0.5–1 kg per week, with high protein intake maintained and moderate water and sodium manipulation in the final days. Team sports like soccer and basketball require 5–7 g of carbs per kg per day and 1.4–1.7 g of protein per kg per day, with emphasis on pre-game carb loading, halftime refueling, and post-game recovery nutrition within 2 hours. Swimmers need high carbohydrate intake (6–10 g/kg/day) due to high training volumes and benefit from antioxidant-rich foods to combat the oxidative stress from pool chlorine. Marathon nutrition involves carb loading at 8–12 g/kg for 2–3 days pre-race, a familiar pre-race meal 3–4 hours before, consuming 30–60 g of carbs per hour during the race, and aggressive post-race recovery with protein, carbs, and electrolytes.
Several common nutrition myths deserve clarification. The claim that you must eat every 2–3 hours to boost metabolism is largely a myth: meal frequency has minimal impact on metabolic rate when total calorie and protein intake are equated, and the thermic effect of food depends on total intake rather than frequency. Detoxing and cleansing are unnecessary because the liver, kidneys, and digestive system already detoxify the body effectively; juice cleanses often lack protein and calories and can impair performance and recovery. Intermittent fasting can aid fat loss but may impair performance and muscle gain if total calorie and protein intake are insufficient or if training occurs in fasted states. The ketogenic diet, a very low-carb, high-fat approach forcing the body to use fat and ketones as primary fuel, may benefit ultra-endurance athletes but generally impairs high-intensity performance due to reduced glycogen availability. Alcohol impairs muscle protein synthesis, dehydrates the body, disrupts sleep, reduces glycogen resynthesis, impairs reaction time, and increases injury risk, with even moderate post-exercise consumption significantly hindering recovery. Finally, supplements are not required to build muscle — a well-planned diet can provide all necessary nutrients — though creatine, protein powder, and vitamin D may be convenient and beneficial when dietary intake is insufficient.