Fitness Fueling: Gender-Specific Nutrition Concerns

When it comes to fitness and sports, there are different designs and measurements of shoes, gear, training metrics and even bicycles for men and for women. So it makes sense that there should also be a different set of nutrition requirements for men and women, right?

This a topic largely up for debate as more gender-dependent nutrition research is needed to answer the question conclusively. Until recently, most research regarding nutrition, especially sports nutrition, has been carried out using males due to ease in controlling for hormonal fluctuations. However, these hormones and life phases tend to create the most nutritional discrepancy between genders.

Outside of this, however, most dietary recommendations are better classified based on body size, composition and sport-specific needs rather than gender.

Calorie requirements are one instance where women really are like small men. Calorie needs are based on body size and activity levels. Meaning a tall, muscular person needs more calories than a short, skinny person, regardless of gender. It just so happens that more women are smaller with less lean muscle mass than men, earning them fewer calories, even for the same activity level.

Essential body fat values are higher in females, meaning even the leanest of healthy female athletes would still have a higher percentage of fat than the leanest of male athletes. Athletes competing in sports that emphasize weight are most at risk for disordered eating (abnormal and unhealthful eating habits). More than 30% of athletes report suffering from disordered eating — and while women are more at risk, men are becoming a larger portion of the affected count. To have a healthy body and reach optimal performance, bodies of both sexes need to consume enough energy to meet needs.

Here’s where things get much more interesting. Studies have shown that during endurance training, men utilize a higher percentage of energy from carbohydrates while women utilize fat more efficiently. Specifically, men derive, on average, 65% of their energy from carbohydrates and 29% from fat, while women use 56% and 41% respectively. While the exact reason women utilize a smaller proportion of carbohydrates for energy than males is unknown, it is thought to be a combination of the hormone estrogen and differing ratios of muscle fiber types.

Despite this, studies have shown both genders respond well to carbohydrates provided during activity for performance increase and post activity for recovery purposes. Some research has found women don’t see the same performance benefits men do from carbohydrate loading unless they consume more than 8 grams of carbohydrate per kilogram of bodyweight. While that might seem high, it is within the guidelines of 6–10 grams of carbohydrate per kilogram of bodyweight for endurance carbohydrate intake. What this really indicates is women are likely not consuming adequate carbohydrates and overall energy needed for endurance performance.

Women should increase the duration of their carbohydrate loading to 3–4 days (instead of 1–2) and consume a much higher caloric intake during this time to make it easier to get in the beneficial amount of carbohydrates. In addition to modifying the carb-load process, females may benefit from changing carbohydrate consumption slightly depending on their menstrual cycles. During the follicular phase, which starts when your period starts and lasts roughly 16 days, a woman’s body has been shown to utilize more carbohydrates than in other phases.

While athletes require more protein than the average person, the recommendation for daily protein intake is the same for both genders, 1.2–2 grams/kg, and is dependent on body size and activity level.

One big difference between genders is males show a greater response in fat-free muscle mass to creatine supplementation than women. This is likely due to testosterone levels, the primary male hormone, which works to increase muscle mass. However, both genders benefit in intensity performance after a creatine routine and both respond well to protein (at roughly 10 grams total) consumed immediately after training for recovery purposes.

Both genders also oxidize more leucine, a branched chain amino acid, in training and rest than non-athletes and might support supplementing with the amino acid.

As earlier mentioned, it is well documented that women utilize more fat than men during activities. Estrogen, the primary female hormone, is most responsible for how women respond to fat differently; it promotes fat storage and inhibits muscle formation. This does not mean women should adopt a low-carbohydrate eating style as carbs are essential for hormone regulation. Both genders should take in 20–30% of daily calories from healthful fat sources.

There are several vitamins and minerals that vary in recommended dietary allowances between men and women. For example, men should take in more B1, B3, selenium and zinc, while women should get more iron. Most of these nutrient differences are small.

Iron is a particularly important one for those engaged in athletic training. All athletes, especially runners, are at risk of greater iron losses through food strike hemolysis. However, females have much higher iron losses through monthly menstruation which is why they should consume roughly three times as much as males. In general, active individuals need more vitamins and minerals to support high energy burn, recovery and performance. Special attention should be paid to consuming a diet high in (and possibly supplementing with) vitamin D, B vitamins, calcium and iron. If a female athlete is pregnant or breastfeeding, the vitamin and mineral needs are greatly altered and special attention should be paid to proper nutrition during these life events.

Both genders in weight-dependent sports (cycling, dance, running, rock climbing) are at risk of restricting intake too much to properly support health.

However, women are more susceptible to insufficient energy availability; underconsuming calories needed for high-activity levels, which leads to a host of health issues including decreased performance, delayed recovery, high risk of stress fracture and hormonal imbalances. Female athletes also have more variability and specific nutrition needs depending on monthly menstrual phase and phase of life (pregnancy, breastfeeding, menopause).

More studies on athlete nutrition, especially those using female subjects, are needed to draw gender-specific fueling conclusions. While there are some differences between genders when it comes to properly fueling their fitness, they are minor. Elite and professional athletes at the very top of their game could benefit from tweaking their diets to include these tiny differences in gender. However, the general fitness buff or age-group athlete will see the biggest performance benefits from focusing on a balanced diet of whole foods.