Dr. Stacy Sims: Over 50% of Female Athletes Aren’t Eating Enough

Sims emphasizes that the majority of recreational female athletes are unknowingly in an energy deficit because they stop eating when full, not when adequately fueled. For hybrid athletes, the combination of high-intensity anaerobic work and heavy strength training places extreme demands on both the muscular and central nervous systems. By intentionally adding eating opportunities and including fiber and protein at each, women can simultaneously address energy availability, gut health, and structural repair. She frames this as a joyful rejection of societal pressure on women to eat little, insisting that food is a performance tool, not a guilt source.

Sims describes a common scenario: a woman runs hard one day, feels flat the next, but still plans to lift heavy. She argues this prevents hitting the loads necessary to stimulate strength gains, effectively wasting the workout and prolonging the recovery deficit. She ties this to the larger allostatic load concept—life stress adds to CNS fatigue, so when life demands are high, rest becomes even more critical. Her own injury story illustrates the consequence: ignoring accumulated stress leads to breakdown. She wants women to understand that rest is the active ingredient in getting fitter, not a sign of weakness.

Sims explains that for hybrid athletes combining high-intensity anaerobic work with heavy strength training, the fueling demands are extremely varied. Different muscle systems and the different mechanical pulls on muscle tissue during activities like sled pushes or tempo runs create high metabolic and central nervous system demands. Most women stop eating when they feel full, but satiety often comes before they've consumed enough to support adaptation, leaving them in deficit. She emphatically rejects the social pressure for women to eat sparingly, encouraging them to 'be happy that we can eat' and to view food as essential for performance and injury prevention. The message is a direct push against diet culture: the 'demure little woman' stereotype has no place in sport.

Sims describes scenarios where women juggle jobs, kids, and partners while trying to train competitively. That 'life stress' is a real stressor that raises energy requirements and taxes the central nervous system, making the body more vulnerable to injury. She shares a personal experience: she attributes one of her own injuries to coming into a competition severely jet-lagged and carrying the emotional stress of an unexpected death in the family at Christmas. Despite telling herself 'Yeah, I'm fine,' the accumulated stress was too much. She stresses that even when exercise is used as a stress reliever, there must be other coping mechanisms to lower allostatic load, and recovery days are critical when life stress is high.

Sims connects the need for adequate fueling to the failure of trendy diets to account for total load. She says a woman who trains hard, works, and runs a household cannot simply follow carnivore or fasted protocols without risking under-recovery. The 'individual' must look at the demands of her life and tailor eating habits accordingly. This is a call to step away from cookie-cutter diet rules and instead listen to one's own body and energy requirements, particularly as they fluctuate with life stress and training phases.

Sims uses the example of a hybrid athlete who ran hard the day before and now feels flat but still plans to do strength training. She asks, 'How do you feel? Well, I feel a little bit flat. Then why are you going to do strength training?' The answer is that you won't reach the loads needed to stimulate muscle adaptation; you're just adding stress without the potential for gain. She explains that exercise is the stress stimulus, and recovery is where the body rebuilds stronger. If you never allow that rebuilding, you don't get the adaptation. This principle applies especially to women balancing high-intensity cardio with heavy lifting, where CNS fatigue accumulates quickly.