You may have often wondered why you are gaining weight as you age despite the fact that you have not changed your eating habits.  The nutrition needs of the older human body are complex because as we age there is a decreased need for calories and an increased need for nutrient-dense food.

Why our Nutritional Needs Change as We Age in Colorado

To understand why our needs change as we age there are a few terms to delve into first. 

  • A calorie is a unit of measure of the amount of energy in food and how much energy will be transferred to the person who eats it. 
  • Total Energy Expenditure (TEE) is collectively comprised of the energy to maintain physiological functions, support physical activity, and process food.  It can be thought of as the total energy expended by the body.  Sometimes TEE is referred to as TDEE or Total Daily Energy Expenditure.
  • Basil Metabolic Rate (BMR) is the hourly rate of energy expenditure for the body to perform involuntary functions such as digestion, elimination, circulation, breathing, and building and repairing cells.  BMR accounts for 50 to 70% of TEE.
  • Thermic Effect of Food (TEF) is the energy required to process food and accounts for only 10% of TEE.
  • Physical Activity is the energy required for movement and accounts for 15-30% of TEE.

Now that we understand that calories are the amount of energy transferred to us through the foods we consume and we know that our TEE is the energy that we expend in a day, we can see that if we have decreased TEE as we age and continue to consume the same number of calories, we will have excess calories in our body that are stored as fat.

An August 2021 study published in Science found that at approximately 60 years of age, TEE and BMR declined by 0.7% per year.  For subjects 90 and older, the adjusted TEE was about 26% below that of middle-aged adults.  Let’s take a look at the factors that contribute to TEE.

Factors influencing BMR, the largest component of TEE, include body composition, age, sex, nutritional status, and genetics.  Of these, only body composition and nutritional status are mildly modifiable.  The second largest component of TEE is physical activity.  As we increase our activity level our TEE goes up and then so too does the number of calories we can consume in a day.  The final and smallest component of TEE is the Thermic Effect of Food.  Recall this is the energy required to process food by your body and is dependent on the type of nutrient that you are digesting.  High-protein foods require the largest amount of TEF and high-fat foods require the smallest.  We can use this information to determine what factors can and can’t be modified to impact our TEE. 

Consider the following to increase your TEE.

  • Increasing your current level of physical activity.
  • Performing weight-bearing exercises to increase your muscle mass and change your body composition.
  • Consume more nutrient-dense foods and less empty calorie foods to increase your nutritional status.

How Older Coloradans Can Determine Their Caloric Need

The USDA MyPlate Tool is a great source to calculate your specific caloric need.  After inputting your age, sex, height, weight, and activity level, you will receive a recommended calorie target to maintain your current weight and potentially a recommended target to achieve a healthy weight.  Free Apps like MyFitnessPal and Cronometer are great tools to help you track your calories.  Below are some examples of results from the MyPlate tool for the three different activity levels. 

*Weights and Heights were chosen based on averages from the January 2021 National Center for Health Statistics Vital and Health Statistics Report Series 3, Number 46

Key Take Aways

  • BMR and TEE have been shown to decrease with age representing a corresponding decreased calorie need in older adults as compared to other age groups.
  • Changing your activity level will affect your daily calorie target.
  • Use the MyPlate Tool to determine your individual caloric need.  Play around with activity levels to see how increasing or decreasing your activity level impacts your calories.  Once you obtain your target, click on the resultant calorie amount for a link to a suggested meal plan with serving portions for each food group.
  • Avoid empty calorie foods and aim for nutrient-dense options to get more bang for your buck with your decreased calorie needs.
  • For more information on Healthy Eating refer to our post Ensuring Seniors Eat Healthy.
  • Consult with a physician or registered dietician before making any dietary changes.
  • Females should never consume less than 1200 calories per day, and 1400 for males.  Remember you need calories for your TDEE, a high percentage of which covers your basic involuntary bodily processes.



Healthy Eating for Older Adults USDA MyPlate

January 2021 National Center for Health Statistics Vital and Health Statistics Report Series 3, Number 46

McGuire, Michelle, et al. “What Determines Energy Expenditure.” Nutritional Sciences, Fourth ed., Cengage Learning, Boston, MA, 2016, pp. 303–313.


MyPlate Tool USDA MyPlate

MyPlate Widget USDA MyPlate

Nutrition for Older Adults from Medline Plus

Surprising findings about metabolism and age from Harvard Health Publishing

By Gretchen Stevenson RN, BSN | August 8, 2022