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June 21, 2022 | | Nutrition

Fueling Across the Lifespan


I have partnered with the National Dairy Council to bring to Fueling Across the Lifespan with Dairy.

At any stage in life, we can feel fatigued. Some days it just might feel like we can’t get out of bed, but why is this? What reduces our energy levels and causes us to feel tired throughout the day? To find a potential explanation of what may cause us to lack energy, we first need to understand where energy is really coming from.

The source of energy in the body is called adenosine triphosphate (ATP), and it provides releasable energy for us to complete many functions, such as muscle contraction, blood circulation, and various muscle movements.1 So the next question becomes, how can the body produce this? How can we get more energy?

To form ATP, we must eat food. Food is an energy source that is made up of macronutrients, which are protein, fats, and carbohydrates. These macronutrients can either be used as energy or used as building blocks for other molecules in the body.2,3 Once eaten, the macronutrients are digested and broken down into their simplest forms, which are amino acids, fatty acids, and glucose.4 The primary source of energy in the body is glucose, which is a carbohydrate.3,4 Although our brain only makes up about 2% of our body weight, it uses about 20% of the energy from glucose.5 So, to make sure that we have enough energy both physically and mentally, we must make sure that we are fueling properly and eating enough carbohydrates throughout the day.5

Fueling the body properly is important at any stage in life. When we feel tired, this can be directly related to not eating enough food.5 From infancy to older age, the human body will always require the same basic needs: macronutrients, essential vitamins and minerals, and water. Although we will still require the same nutrients throughout life, the amounts of these nutrients will vary between life stages. Age, gender, height, weight, and activity level will all affect nutritional needs. Let’s look at how these needs can change as we age.

During childhood, consuming enough nutrients is essential to reach full potential regarding growth, development, and health. Nutrition-related problems such as obesity, iron-deficiency anemia, undernutrition, and cavities are common at this age.6 At ages 2-8, needs will not vary much between males and females because puberty has not occurred yet. On average children will need about 1000-1600 calories between ages 2 through 4, and about 1200-2000 calories between ages 5 through 8.7 Emphasis should be put on iron, zinc, vitamin D, and calcium to promote growth and bone mass accumulation. Meat, fish, poultry, and fortified breakfast cereals are great sources of iron to incorporate into the diet. Vitamin C such as citrus fruits or bell peppers can help increase iron absorption as well. Pork, chicken, and fortified breakfast cereal are also great zinc sources.6 Daily sun exposure can allow for increased vitamin D levels, which is also important at any age. Vitamin D fortified milk is another great option to increase vitamin D and calcium intake. Other dietary sources that offer calcium are Greek yogurt, cheese, and other dairy products. As children begin to reach adolescence between ages 11-17, these nutrients remain extremely important for proper growth and development to continue.

During adolescence, both calorie and vitamin and mineral needs begin to significantly increase due to puberty and growth spurts. In addition to iron, zinc, vitamin D, and calcium, folate is another important mineral to prioritize during adolescence. Folate plays an important role in DNA, RNA, and protein synthesis which occur at increased rates during puberty.6 Folate can be found in dark leafy greens, fortified breakfast cereals, beans, and whole grains. Metabolism is closely associated with lean muscle mass, so adolescents who experience increased height, weight, and muscle mass, specifically males, will have very high calorie needs. If calorie needs are not met, growth can be stunted, and sexual maturation can be delayed.6 To avoid this, we need to make sure calorie intake is adequate to help provide adolescents with enough energy to perform in school and extracurricular activities and continue growing at a healthy rate.

In adulthood, fueling properly throughout the day is important to provide enough energy and help preserve muscle and bone mass. Adequate calcium intake is very important, especially for women who are more prone to osteoporosis.6 The consumption of dairy, especially milk, is often promoted to the adolescent population, but dairy consumption should continue well into adulthood to ensure calcium, vitamin D, and protein intakes are being met. Vitamin D helps aid calcium absorption, so it is also a good idea to make sure that you are going outside to get enough sunlight. In addition to calcium and vitamin D, more than 90% of women and 97% of men do not get enough dietary fiber in their daily diet.7 Fiber intake can be increased by fueling properly with a diet rich in fruits, vegetables, and whole grains. A high-fiber diet can help with bowel motility, a longer sensation of fullness when eating, and decreasing the risk of heart disease.7 When the gut is happy, we feel happy too.

As aging progresses, muscle and bone loss can become a concern. About 50% of women and 30% of men aged 71 and older do not meet their daily recommended protein intakes, which can contribute to muscle loss.7 To prevent this, it is important to put emphasis on getting enough protein, calcium, and vitamin D every day.6,7 By eating enough poultry, seafood, meat, dairy, and legumes throughout the day, protein intake can drastically be increased. Incorporating more dairy into the diet will help not only increase protein intake, but calcium and vitamin D intake as well. Foods like Greek yogurt, cottage cheese, and milk are all great dairy sources to incorporate into the diet to help increase these nutrients throughout the day.

At any stage in life, when we fuel properly to ensure adequate intakes of all nutrients are met, this will sustain our energy levels. To convert the nutrients in food to the energy that our body uses, there are many vitamins and minerals involved in these reactions.  are all essential in this conversion process to create energy.5 Without enough of these nutrients, energy production cannot occur.5 To ensure we have adequate levels of all these vitamins and minerals in the body to help create energy, it is important to fuel ourselves with a variety of fruits, vegetables, whole grains, nuts, seeds, dairy foods, and various animal proteins. Having a diet filled with a variety of whole foods for breakfast, lunch, and dinner will decrease the likelihood that any nutritional deficiencies will occur and support this energy producing process.

In addition to diet, there are other important variables that can play an important role in increasing energy levels. The first is exercise. Although it may seem counterintuitive to expend more energy to increase energy levels, research shows that even low-intensity exercise can decrease fatigue. One study found that sedentary individuals experienced a 20% increase in energy levels and a 65% decrease in fatigue with just 20 minutes of low-intensity aerobic activity three times per week.8 This leads me to the next variable: stress. As physical activity levels increase, this can help reduce stress and anxiety levels and promote better sleep. Low stress and proper sleep will play a large role in energy production. Our body is made to handle stressful situations in short bouts, but when this stress becomes chronic, it can really take a toll on the body. Chronic stress can have exhausting effects on all systems of the body. When we are chronically stressed, our muscles remain tense, our rate of breathing and heart rate increases, and our stress hormones remain elevated.9 All of this requires extra energy. To help control stress levels, it is important that we consistently get enough sleep, which is the final factor to consider when trying to improve daily energy levels. Most adults need about seven to nine hours of sleep each night, and about 13-23% of this time should come from deep sleep.10 Deep sleep is important to restoring energy because this is the stage where energy (ATP) stores are replenished.10 To ensure you are getting enough deep sleep each night, allow yourself ample time to fall asleep without any interruptions. Too much constant stress without enough sleep can deplete our energy levels, which leaves us feeling continuously tired.

Start breaking the cycle to increase your energy. When you begin exercising, your stress levels can decrease which allows for improved sleep. Improved sleep allows for increased energy production. When we pair these factors with properly fueling ourselves throughout the day, we can maximize our energy levels. This may sound like a lot of habits to form, but try to work on one area at a time. Try working on sleep or exercise first, then once you have mastered this, work on adding in a new habit. You wouldn’t let your car run on empty, so don’t let your body either.

If you are struggling to think of ideas to help fuel yourself during the day, try some of these easy higher protein snack options:

  1. Nonfat Greek yogurt cup with granola
  2. Low fat cottage cheese with berries
  3. Reduced-fat cheese, almonds, and grapes
  4. Jerky and reduced-fat mozzarella stick
  5. Protein bar or shake
  6. Whole grain toast with mashed avocado and turkey slices
  7. Whole grain pretzels, sliced bell peppers and celery, and hummus
  8. Steamed or roasted edamame
  9. Chickpea or lentil chips with guacamole
  10. Chicken or tuna packet with whole grain crackers



  1. Dunn J, Grider MH. Physiology, Adenosine Triphosphate. StatPearls. Treasure Island (FL), 2022.
  2. Alberts B, Johnson A, Lewis J, et al. Molecular Biology of the Cell. 4th edition. New York: Garland Science; 2002. How Cells Obtain Energy from Food. Available from: https://www.ncbi.nlm.nih.gov/books/NBK26882/
  3. Gagliardi C. The three primary energy pathways explained. ACE Blog. https://www.acefitness.org/fitness-certifications/ace-answers/exam-preparation-blog/3256/the-three-primary-energy-pathways-explained/. Published March 7, 2019. Accessed April 14, 2022.
  4. Food Energy and ATP. (2021, March 6). https://bio.libretexts.org/@go/page/13848
  5. Tardy AL, Pouteau E, Marquez D, Yilmaz C, Scholey A. Vitamins and Minerals for Energy, Fatigue and Cognition: A Narrative Review of the Biochemical and Clinical Evidence. Nutrients 2020;12(1) doi: 10.3390/nu12010228
  6. Brown JE, Lechtenberg E, Murtaugh MA, et al. Nutrition through the Life Cycle. Boston, MA: Cengage Leaning; 2017.
  7. U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition. December 2020. Available at DietaryGuidelines.gov.
  8. University of Georgia. (2008, March 2). Low-intensity Exercise Reduces Fatigue Symptoms By 65 Percent, Study Finds. ScienceDaily. Retrieved April 14, 2022 from www.sciencedaily.com/releases/2008/02/080228112008.htm
  9. Stress effects on the body. American Psychological Association. https://www.apa.org/topics/stress/body. Published November 1, 2018. Accessed April 16, 2022.
  10. Deep sleep: What it is and how much you need. Sleep Foundation. https://www.sleepfoundation.org/stages-of-sleep/deep-sleep. Published March 11, 2022. Accessed April 16, 2022.