September 10, 2015

Sports nutrition: Are you eating enough?

As summer comes to a close (sigh) and we transition to a new school year (double sigh), the stage is set for the start of fall sports, including football, soccer, cross country, swim team, volleyball, tennis, golf"¦am I missing any? Often the start of a sports season represents an increase in energy expenditure, since not everyone is active year-round. With the intense activity that comes with these sports, maintaining good nutrition is important. If teens simply continue to eat the same amount as they did prior to intensifying their exercise, they will develop a relative caloric deficiency, meaning they are spending more energy than they consume. Simply put, they aren't giving their body enough fuel, and this can have some consequences.

Sometimes people are surprised to learn that concentration and memory is linked to nutritional intake. Glucose (from carbohydrate intake) is what fuels the brain. If the teen is barely eating enough to cover the energy that they spend in sport, they haven't left a lot of energy for the brain. Suboptimal nutrition can cause teens to work twice as hard to concentrate in class, which can lead to declining classroom performance.

Female athletes are especially sensitive to low caloric intake, a phenomenon called the Female Athlete Triad, which includes low caloric intake (with or without disordered eating), menstrual irregularities, and low bone mineral density. Often the first sign of energy deficiency is menstrual irregularities, making regular periods an important "vital sign" for nutritional status. The menstrual cycle requires energy input from the body; when the body is stressed by caloric deficiency, it will elect to stop having periods and redirect that energy to essential bodily functions (like keeping the heart beating). Therefore, in adolescent girls that were previously having regular periods, the loss or irregularity of their periods is a huge red flag. Health care providers also use menstrual periods as a proxy for amount of circulating estrogen and bone health. The body must make a sufficient amount of estrogen to have regular periods and this level of estrogen is also essential for bone health. Estrogen is a potent inhibitor of bone reabsorption and it increases the amount of calcium that is absorbed from the intestine. The longer that a teenage girl does not have her period, the greater the amount of bone turnover. This results in weaker, more porous bones that are at greater risk for stress fractures.

Interestingly, low BMD has been shown in male athletes as well, including long distance runners, and athletes of non-weightbearing sports such as cyclists and jockeys. The theory behind low BMD in male athletes is similar to the Female Athlete Triad, basically that the low net-energy leads to hormone derangements that leads to weaker bones. The International Olympic Committee has recognized this spectrum similar to the Female Athlete Triad in males, and has therefore renamed this spectrum as Relative Energy Deficiency in Sports.

A good rule of thumb for maintaining adequate nutrition is eating 3 meals and 2-3 high-quality snacks each day. A meal should consist of a minimum of 3-4 separate components, such as a a vegetable or fruit, a protein, a whole grain carbohydrate and a healthy fat..

An example of a healthy meal plan would be:

Breakfast — orange, bowl of oatmeal, 2 low fat sausage links, skim milk OR Breakfast Burrito (egg, salsa & cheese on whole grain tortilla)

Morning snack — Greek yogurt with granola & berries, water

Lunch — turkey sandwich (whole grain bread, turkey, spinach & cheese), salad, apple, skim milk

Afternoon snack — pepper slices and snap peas with hummus, water

Dinner — skinless chicken breast, roasted potatoes, green beans and pineapple

Evening snack — (optional) tortilla with peanut butter & banana, water

Fruit & Nut trail mix, string cheese and/or cottage cheese are great additional snack options when teens are more active during their sport seasons.

And don't forget hydration! Drinking water throughout the day is important for active teens. Your body can lose liters of sweat in an hour of vigorous exercise. Sports drinks are fine, but not necessary. Water is perfect for most athletes.

A word of caution to any teen who plans to (or is encouraged to) lose or gain weight to improve performance in their sport. Changing your body weight must be done safely, or it may do more harm than good. Keeping your body weight too low, losing weight too quickly, or preventing weight gain in an unnatural way can have negative health effects. Taking supplements to gain weight or muscle also can heave negative health effects. It is important to set realistic body weight goals. To make sure reaching a healthy weight is done is a safe way, teens should work with a registered dietitian and a physician.

To make an appointment with a UW Health registered dietitian, call (608) 890-5500.