Are Women Undereating Carbs? Why Low Carb Backfires for Muscle, Hormones and Energy

Sims addresses the psychological barrier by embedding extra calories into the athlete's existing routine. She avoids calling it a meal, instead labeling it as necessary fuel. By starting with small additions—like a pre-workout snack and a post-workout recovery shake—the total daily intake rises significantly without the woman feeling she's 'eating more.' Over weeks, this stabilizes energy, improves training performance, and alters body composition positively, creating a virtuous cycle of motivation.

Sims advises this simple habit as a first step for insulin-resistant clients. Even without changing diet composition, the post-meal movement increases glucose disposal, making the body more efficient at handling carbohydrates. Combined with fiber-bound carbs and later sprint intervals, it improves overall insulin sensitivity.

Sims integrates this with building muscle as a glucose sink. As muscle mass increases and becomes more insulin sensitive via sprint training, the body's carbohydrate tolerance improves, reducing the metabolic burden of insulin resistance. This approach works synergistically with increased carbohydrate intake to support training and body composition.

Stacy Sims explains that insufficient carbohydrate intake causes low carbohydrate availability, which disrupts the endocrine and immune systems, impairs muscle and bone building, and creates a 'tired but wired' state with poor sleep and stubborn belly fat. Even if total calories are adequate, low carbs alone can trigger these effects. She notes that women need more carbohydrates than men due to hormonal differences and higher glucose needs. In her clinical experience, boosting carbohydrate intake resolves many of these symptoms within weeks, improving body composition and energy without other changes.

Sims describes how she works within the woman's existing day, introducing extra calories through performance-focused nutrition rather than meals. By framing them as necessary fuel for exercise sessions, the addition of 500 calories per day becomes mentally acceptable. Over 3-4 weeks, she gradually phases in these new eating habits, which minimizes scale shock from glycogen storage and water weight, and leverages improved training energy to create a positive feedback loop of motivation and adaptation. She emphasizes that this approach avoids the psychological backlash of labeling it as overeating.

Stacy Sims notes that when a woman is under-eating carbs, labs often show a TSH on the high end, DHEA on the low end, sex hormone binding globulin up, cortisol dysregulated, and a paradoxical combination of very low insulin with high fasting blood sugar. She sees this constellation in approximately 70% of her patients presenting with fatigue, irregular cycles, and belly fat. Increasing food, especially carbohydrates, normalizes these markers and resolves visceral fat accumulation.