If you've ever followed sports nutrition advice and wondered why it doesn't quite fit, why the guidance feels slightly off, or the recommendations don't map to how your body actually responds - you’re not alone. Most of it wasn't built for you.

The majority of sports nutrition research has historically been conducted on male participants. Women's hormonal fluctuations, metabolic differences and unique physiological responses to exercise were considered too complex to control for, so researchers defaulted to the simpler option. Sound familiar?

Two significant studies published in 2025 are beginning to change that. Here's what they found, what it means in practice and why it matters for every woman who moves her body; whether she's training for a marathon or just trying to show up consistently.

The Research Gap Is Real And It Has Consequences

A systematic review published in Nutrition Reviews analysed the existing evidence on nutrition strategies for female athletes and physically active women. The conclusion was clear: women have distinct physiological needs that influence how nutrition affects performance and recovery, but the research base to support female-specific guidance remains thin.

Women metabolise substrates differently to men. Hormonal fluctuations across the menstrual cycle affect energy requirements, recovery rates and how the body responds to training. And yet most of the guidelines women are handed, from protein targets to carbohydrate timing, were derived from studies that didn't include them.

This isn't a minor detail. It's a structural gap with real implications for how women fuel, recover and perform.

What the Evidence Actually Says

Despite the limitations, the 2025 review synthesised findings from available research to offer some of the clearest female-focused guidance to date. Here's what stands out:

Carbohydrates are not the enemy, they're the fuel.

High-carbohydrate diets support endurance and prolonged performance by maintaining glycogen stores. Pre-exercise carbohydrate-rich meals improve energy availability, and using a mix of carbohydrate types improves how efficiently the body absorbs and uses them. If you've been under-fuelling before long or high-intensity sessions in the name of cutting carbs — this is the research telling you to stop.

Protein timing matters as much as quantity.

The review found that spacing protein intake across five to six meals per day, with around 25g of high-quality protein per meal, supports muscle protein synthesis, recovery and body composition. This is particularly important for women doing resistance training or training at high volumes. It isn't just about hitting a daily target, it's about when and how that protein is distributed.

Certain supplements have evidence behind them.

Caffeine at 3-6mg per kilogram of body weight taken around 60 minutes before exercise has been shown to improve strength, power and endurance. Beetroot juice and other nitric oxide precursors may enhance blood flow. Beta-alanine supports performance in high-intensity efforts. And micronutrient supplementation (particularly Iron and Vitamin D) is essential when deficiencies are present, which in women is more common than most guidelines acknowledge.

What Marathon Research Tells Us About Women Specifically

A second study published in Sports Medicine Open in 2025 looked at how nutritional intake and timing affect marathon finishing times. Of the 160 runners analysed, only around 12% were women, which is itself a telling statistic. But the female-specific findings are worth paying attention to.

Women tend to oxidise more fat and less carbohydrate than men at moderate intensities. This means their carbohydrate needs during endurance events may differ from male-derived recommendations and the study found that women were more likely to under-consume carbohydrates relative to body weight during races, potentially limiting performance as a result.

Post-race protein intake was insufficient across the board, but women tended to consume lower absolute amounts. Given the role of protein in muscle repair and recovery, particularly when training volume is high, this is a gap worth addressing. The recommendation is around 0.3g per kilogram of body weight per hour in the post-race window.

On hydration, women consumed similar fluid volumes to men but lower sodium intake. Because of differences in body mass and sweat rates, women are actually more prone to hyponatraemia (low blood sodium) during long events if electrolytes aren't carefully monitored. This is one of the clearest examples of why applying male-derived hydration guidelines to women can be not just ineffective but actively counterproductive.

The Bigger Picture

Both studies point to the same conclusion: women cannot simply apply male-derived nutrition guidelines and expect the same results. Hormonal fluctuations across the menstrual cycle affect energy metabolism, hydration needs and recovery rates in ways that most current research hasn't adequately accounted for. Life stage matters too, the nutritional demands of a woman in her 20s training for her first marathon are different from those of a woman navigating perimenopause while maintaining a consistent movement practice.

What both reviews call for, clearly and consistently, is more female-focused research. Better-controlled studies. Larger sample sizes. Methodologies that account for cycle phase, hormonal status and the full complexity of women's physiology.

Until that research exists at the scale it should, the practical guidance is this:

• Fuel with carbohydrates before and during long or high-intensity sessions, don't under-eat in the name of performance 

  
  

• Space protein intake throughout the day, aiming for around 25g per meal, to support muscle repair and recovery

  
  

• Monitor sodium and electrolyte intake carefully, particularly during endurance events 

  
  

• Use caffeine strategically, adjusted for your body weight, around 60 minutes before training 

  
  

• Address micronutrient deficiencies (Iron and Vitamin D in particular) rather than assuming they don't apply to you

  
  

• Seek nutrition guidance that accounts for your hormonal profile, life stage and training load, not guidance built around someone else's biology

  
  

A Note From Free Soul

Women's sports nutrition has spent decades working from incomplete data. These studies are part of a growing body of research that is beginning to ask the right questions and the answers matter for every woman who takes her health and performance seriously.

At Free Soul, we formulate with women's physiology in mind. Because nutrition that works for you starts with understanding how your body actually works.

This article is for educational purposes and does not constitute medical advice. Always consult a qualified healthcare professional or Registered Nutritionist before making changes to your diet or supplementation.