Bone Health and Teens

The body is an incredible machine. It performs countless functions without our knowing and is able to turn the food we eat into energy to do homework, play sports, lift the remote to change channels, walk the shores of Lake Mendota, and do every other activity we do. But what happens when our bodies don’t get the energy they need? This is a topic that has been studied by many doctors and organizations, including the International Olympic Committee.

Yes, our bodies are incredible machines, but they are also just that–machines. Machines take energy to work, and in the case of humans, the energy that makes things work is food. The body is able to store energy in fat cells when food is abundant (think of Thanksgiving dinner or other holidays) and is able to use this stored energy when times aren’t so good (when the lunch at school isn’t your favorite). The body is able to maintain this balance well, but if the body is in a state where its energy stores are constantly being used up and not replaced, things start to go awry.

One of the first things that happens when the body is short on food is to divert energy away from functions that are not necessary for everyday survival. The heart and the brain take priority over all other parts of the body, and the body will ration the remainder of its energy to other organs that are important to survival. The reproductive organs are important, but in terms of surviving each day, they are not essential. This means the reproductive organs one of the first places that energy is diverted away from when the body does not have enough to go around. This may not seem important, but if this goes on long enough, something funny happens. Girls who are old enough to have started having their menstrual cycles will stop having periods. This can be seen if not enough energy is consumed (ie not eating enough), but it can also be seen if too much energy is used without having a compensatory increase in food (ie exercising too much). Endurance athletes or athletes who have to watch their diets carefully to maintain a certain weight are at the highest risk of running low on energy for long periods of time and seeing effects like this. While not having menstrual cycles may not seem like a big deal, what happens to the body as a result can have long-term effects on health.

Menstrual cycles result from the intermittent rise and fall of a hormone called estrogen, but estrogen does many more things — one of these things is to make your bones strong. When the human body is young, bones are being built to be as strong as possible. In medical language, we refer to the strength of ones bones in terms of bone density, and younger individuals have the strongest (the most dense) bones. This strength tends to decrease over time as we get older, and this is an unfortunate consequence of aging. When bones become too weak, they progress through a series of changes where they become less hard (osteopenia) until they become very fragile and prone to breaking (osteoporosis). If not enough energy is available to children or teenagers, estrogen will not be able to do its job and their bones will not become as strong as they could possibly be, and they can develop osteopenia or osteoporosis at very young ages.

Girls were specifically mentioned earlier because if they are going through puberty they may stop having menstrual cycles, and this is an important warning sign of not having enough energy available to the body. Not having enough energy, however, can have effects at any age. This constellation of changes used to be referred to as the Female Athlete Triad — the triad was composed of not having adequate nutrition, not having menstrual cycles, and having weakened bones. As more studies have been done, it’s been found that this does not affect just girls–males are also at risk of not having enough energy and developing soft bones. Since both boys and girls can be affected, these changes have been renamed Relative Energy Deficiency in Sport (RED-S).

While the International Olympic Committee has studied this phenomenon, you don’t have to be an Olympic athlete to be at risk of these changes to your health. You don’t need to be an athlete at all, actually. Individuals with eating disorders (not taking in enough energy) suffer the same effects as those who use up too much energy and don’t replace it adequately. Athletes with these imbalances are at risk of decreased athletic performance as well as stress fractures from weak bones. There are sports that require a specific body shape or a specific weight, and while sports like this can be fun and may promote a healthy lifestyle, it is important to be mindful of changes to the body that can happen if bodies are pushed to their extreme limits.

Education about healthy eating and sports nutrition can decrease and prevent the effects of RED-S as well as having coaches, athletic trainers, registered dieticians, and physicians who can all perform a risk assessment and watch for signs of an imbalance in energy available to the body.


UW Health offers a hands-on sports nutrition class, specifically designed for high school athletes, parents and coaches, to help athletes learn to properly fuel their bodies for sporting activities. The next class is on June 13, 2017.



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