As we age, many people blame weight gain on a slowing metabolism. While it is true that metabolism does decrease slightly with age, there are many other factors influencing aging adults’ ability to accurately regulate energy intake.
Factors That Affect Energy Balance
To begin, older adults have a reduced perception of hunger and impaired satiety cues. This means that as we age, we experience an energy imbalance due to an overall impaired regulation of food intake through overeating and/or undereating.
Aging is also associated with impairments in several hormonal systems, which can affect metabolism. We experience altered synthesis and/or secretion of certain gut hormones during the aging process. One example involves the satiety hormone Cholecystokinin (CCK). CCK is responsible for stimulating the digestion of fat and protein. Elderly adults typically have fasting levels of CCK five times higher than young adults, which may lead to a decrease in hunger. As we age, our stomachs also empty at a slower rate, which is also linked to decreased hunger and increased satiety.
There are also changes in the patterns of dietary intake and the variety of foods consumed with increasing age. We naturally experience age-related declines in taste and smell sensitivity, some of which can be associated with the use of medications. This also occurs due to a natural loss in the number of functional taste buds. For example, older adults have increased thresholds for salt and other specific tastes that creates an aversion to foods they may identify as ‘bland’, potentially leading to an overall decrease in food intake.
Social isolation is another factor affecting metabolism as we age. Studies have shown that overall food intake is less when eating alone compared to meals eaten with company. The difference between the two situations can be as much as 30% more food eaten when not alone. Consistent undereating can put an unnatural and unnecessary stress on metabolism.
How Does Age Affect Metabolism?
Basal metabolic rate (BMR) is the number of calories required to keep your body functioning at rest. It is typically the largest component of energy expenditure and metabolism, comprising about 50-70% of total energy expenditure in most adults. We experience a natural decline in BMR of about 1-2% each decade as we age, causing our bodies to require less calories at rest. This means that older adults are not as hungry as often, and should therefore concentrate on nutrient-dense foods such as lean protein, fruits, vegetables, dairy, legumes and nuts and seeds.
As you can see, there are many factors affecting your body’s ability to metabolize food during the aging process. In order to appropriately manage your food intake, it is important to first understand how your metabolism changes over time.
For additional assistance on understanding your body’s energy needs, meet with a nutrition professional. Start with a no-obligation nutrition consultation with me, Elite’s Registered Dietitian!
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Written by Sarah Brunner, RDN, CD; Elite Sports Clubs Registered Dietitian
Sarah is certified in food allergies/intolerances and nutritional counseling, Academy of Nutrition and Dietetics; has a certificate in Dietetics from Mount Mary University; and a BA in Education and Mathematics from the University of Wisconsin – La Crosse.