Calorie-restricting female runners at risk of lifelong bone issues, study finds

By Hank Schultz contact

- Last updated on GMT

©Getty Images - lzf
©Getty Images - lzf

Related tags: female athletes, Sports nutrition products, Sports nutrition, Sports Nutrition Summit USA

A recent study found that adolescent female runners who were consciously trying to restrict calories to achieve a certain body weight were at risk of osteoporosis and other problems.

The study, published in the January edition of the journal Eating Behaviors​, was set up as a cross sectional study of competitive female cross country runners of 14 to 17 years of age.  The study was conducted by researchers associated with several California universities.

The goal of the study was to see if runners falling into the high Cognitive dietary restraint (CDR) group were also at risk for problems associated with the so-called female athlete triad.

Female athlete triad

The female athlete triad is a combination of disordered eating, amenorrhea and osteoporosis. The issue is exacerbated in sports with high overall energy expenditure, like cross country running, coupled with a perceived advantage for being as lean as possible to achieve the best strength to weigh ratio.  The issues can be further heightened if coaches are not well versed in the best nutrition strategies for female athletes.

In the present study the researchers recruited 40 competitive high school cross country runners who were running at least 25 miles a week and were competing in events of at least a mile in duration.  They used a validated method of assessing energy intake by taking each runner through a detailed food intake questionnaire with the help of a researcher every day for the duration of the 7-day study.

The participants also reported on menstrual function and detailed their training load.  On the eighth day of the study the athletes performed a treadmill test to assess energy expenditure and were assessed for osteoporosis via an X-ray scan.  To assess CDR, the researchers used a Three Factor Eating Questionnaire (TFEQ). Of the 40 participants, 13, or 40%, met the criteria for CDR.

The researchers found the CDR group took in about 37 calories per gram of body weight per day, whereas the group not actively counting calories took in 44 Kcal/kg/d.  The non restrictive group also ate more carbohydrates and more fat than the CDR group. The latter, however, took in more protein and, interestingly, more dietary fiber than did the ‘normal’ eaters. They also ate more vegetables and fruit.  They also found the CDR group scored lower  on a measure of lumbar spine bone mass, a deficiency which could set these young women up for serious problems down the road, the researchers warned.

The researchers said this is the first study of its kind to match up measures of CDR with actual food intake with adolescent female runners. As such, it sets the table for further research into the topic.

“Findings from the current study provide evidence to support use of the TFEQ dietary restraint subscale to identify adolescent runners at risk for under consuming calories, carbohydrates, dietary fat, grains, and lower levels of lumbar spine bone mass. Conversely those with elevated CDR may exhibit higher intakes of dietary fiber, vegetables, and fruit. These findings indicate the need for nutrition education and other prevention efforts to promote adequate intake of energy, carbohydrates, dietary fat, and whole grains, which provide essential nutrients for optimizing the health and performance of young runners,”​ they concluded.

Focus on the female athlete

Clinical nutritionist Dr Susan Kleiner, PhD, a founding member of the International Society of Sports Nutrition, has lectured for years on the issues around fueling strategies for female athletes.  Kleiner said she has often seen coaches pushing athletes to be as lean as possible often to the detriment of their health and ultimately to the detriment of their performance. Kleiner will focus on the issues of nutrition for the female athlete during a session in NutraIngredients-USA’s upcoming Sports & Active Nutrition Summit 2021, which kicks off this week. For more information on Kleiner’s session and other portions of the program, click below.

Source:Eating Behaviors
https://doi.org/10.1016/j.eatbeh.2020.101460
Cognitive dietary restraint score is associated with lower energy, carbohydrate, fat, and grain intake among female adolescent endurance runners
Authors: Wood KL, et al.

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