Nutrition for Active Kids

Teen girls playing soccer

Keeping up with the energy demands of growing tweens & teens is hard enough but then you add in before/after school sports, and it feels like they might eat you if you don’t get the snacks out fast enough!

The demands of physical exercise combined with the rapid growth & development occurring during the tween & teen years increases the energy demands on the body. Not meeting these increased energy needs not only impacts their performance but can also have detrimental health impacts like iron deficiency anaemia, reduced bone mineral density, short stature, menstrual dysfunction, delayed puberty and increased susceptibility to illness and injuries. Nutrition is essential to ensuring these increased macronutrients (protein, carbs & fats) and micronutrient (vitamins & mineral) needs of active tweens & teens are met. Let’s look at how to meet these needs.  

Energy Needs

Active tweens & teens should be encouraged to follow their hunger cues and adjust their food intake to match their daily exercise demands. This may mean that some days include larger meals or more frequent snacks are required to maintain energy levels. Using body cues and other markers of health and growth as indicators of adequate energy is recommended as there is no simple method to adequately assess the exact energy needs of active tweens & teens.  

A wholefood diet with a balance of macronutrients is recommended to ensure the energy needs of active tweens & teens is being met. So, what are these macronutrients and how can you include them?


Carbohydrates provide us with readily available glucose which is our body and brain’s preferred energy source. Glucose is stored in our muscles and liver as glycogen which is released quickly by the muscles during exercise to maintain our energy levels. Carbohydrates should make up 45% to 65% of the diet as insufficient intake can result in early fatigue and muscle breakdown.

Aim to include a source of carbohydrates in a snack after exercise to replenish glycogen stores. Good sources of carbohydrates include wholegrains, vegetables, fruit and yoghurt.


Protein builds muscle and repairs tissues, hair, skin and nails. Active tweens & teens should be aiming to consume protein throughout their day from a variety of wholefood sources not protein powders. Protein should make up 10% to 30% of the diet and takes longer to digest so helps keep active kids fuller for longer.

Aim to have protein rich meals 2-3 hours before physical activity to allow for digestion and then include a protein rich snack (20g) after exercise. Good sources include lean meats, eggs, fish, dairy, legumes, nuts and edamame.


Fats are necessary to absorb fat soluble vitamins (A, D, E, K) as well as the production of hormones and cholesterol which is essential to the growth and development of tweens & teens. Fats should make up 20% to 35% of the diet, with no more than 10% of that coming from saturated and trans fats (e.g. fat in meats, dairy, fried foods and processed products such as biscuits). Fat also takes longer to digest so helps with increasing satiety.

Aim to include fats 2-3 hours before exercise to allow for digestion. Good sources include olive oil, avocado, chia seeds, hemp seeds, flaxseeds, oily fish (mackerel, salmon, tuna, sardines), walnuts, almonds, macadamia.

Now let’s look at the more common micronutrient deficiencies seen in active tweens & teens.


During the tween & teen years there is an increase in muscle mass, blood volume and the onset of menstruation for girls, all of which requires more iron. Iron also delivers oxygen to tissues around the body which is crucial for exercise.

The recommended daily intake is

  • Boys: 8mg/day for 9-13yrs and 11mg/day for 14-18yrs
  • Girls: 8mg/day for 9-13yrs and 15mg/day for 14-18yrs (due to menstruation losses)

Good sources of iron are lean meats, eggs, leafy green vegetables, beans.


Tweens & teens need more calcium than an adult due to the bone growth and development that occurs. In fact, bone density continues to build until around 25 years old where peak density is reached. Ensuring optimal bone growth and density during these years helps to prevent osteoporosis in later life.

The recommended daily intake is 1300mg/day for boys and girls aged 12-18yrs. Which is equivalent to 3-4 serves of dairy products. However, dairy can be an issue for some tweens & teens who react to dairy or experience increased acne breakouts. Some good non-dairy sources to include are

  • Nuts and seeds
  • Green leafy vegetables
  • Fish with bones
  • Tahini (sesame seed spread)

Vitamin D

Vitamin D is also essential for bone health as it is involved in the absorption and regulation of calcium. We produce the majority of our vitamin D from sun exposure as the likelihood of eating enough through food is impossible. Food sources are limited and less biologically active. If your tween or teen doesn’t spend much time in the sun or is always covered in sunscreen or clothing, they may have limited opportunity to produce vitamin D and their levels should be monitored. A supplement may be required when deficiencies are identified.

Food sources include

  • Fatty fish such as salmon, herring and mackerel
  • Eggs
  • Some fortified foods

Now that we have looked at the foods, they need what about fluids?


Active tweens & teens should be well hydrated before exercise, especially in hot or humid conditions and to continue drinking during and after to replenish losses. Fluids help to regulate our body temperature and replace sweat losses from exercise. Even mild dehydration can reduce performance and increase the risk of heat stroke or exhaustion.

Water is the recommended fluid for all active tweens & teens. Sports drinks, like Powerade or Gatorade are not necessary and can lead to excess calories being consumed. In cases of exercise lasting more than 1hr or in high humidity a sports drink may be of benefit to help replace energy and sweat losses. Energy drinks containing caffeine should be avoided around sports.

One last tip is ensuring your tweens & teens understand that they need to be putting in the right fuel to achieve their peak performance. If they are skipping meals and relying on simple, refined carbs they are not going to be performing at their best.

If you have an active tween or teen needing some extra nutritional support you can book in for a consult here.


Picture of Sarah Rock

Sarah Rock

Clinical Nutritionist supporting families to reclaim their health and make peace with food.

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