The average decline in metabolic rate after the age of 20 is estimated to be around 2-5% per decade.1–3 However, the exact rate of decline can vary depending on several factors, such as genetics, lifestyle and overall health. Let's discuss some of the factors that influence the rate of decline in metabolism – and what you can do to increase patients' metabolism as they age.
Loss of Muscle Mass
Sarcopenia can start as early as the age of 25. Average muscle mass loss per decade after the age of 30 is estimated to be around 3-8% per decade. Excessive bed rest is part of the problem.4 In fact, just 10 days of bed rest can cause a healthy older adult to experience a 10% decrease in muscle mass.5
I train my members (in 2023 I like calling patients members, rather than patients) to engage in regular strength training, cardio, whole-body vibration, balance activity and flexibility to prevent muscle mass loss.
I am also a proponent of utilizing blood flow restriction training for individuals ages 20 years and older to enhance muscle growth.
I suggest younger patients get a hormone baseline in their early 20s due to potential factors such as declining testosterone / estrogen levels, chronic illness, and decreased thyroid hormone production affecting metabolism.
Changes in Activity Levels
Common causes include:
Physical limitations: Decreased mobility, joint pain or chronic conditions such as arthritis can make it more difficult to engage in physical activity. Even when healthy young men reduced their daily activity levels from 10,000 steps per day to less than 2,000 (which is not uncommon for many people), they lost 5% of their muscle mass in just two weeks.6
Changes in body composition: As we age, we tend to lose muscle mass and gain fat. I gave my members a challenge this year to gain 3 lbs. of muscle. As the doctor, I will lead by example. Are you in? Social and environmental factors: As we age, it may be more difficult to make new friends. One of my healthy-aging strategies is hanging out with younger people. I also plan on working as long as I can while someday (not too soon) going into semi-retirement. Don't forget, maintaining healthy relationships and staying connected with loved ones is crucial for a long and happy life.
Medical conditions: Heart disease, diabetes and obesity can decrease physical activity levels.
Mental health changes include:
Increased risk of depression: A significant life change such as the loss of a loved one or retirement can trigger depression.
Increased risk of anxiety: History of anxiety predisposes this later in life.
Increased risk of cognitive decline: Age-related cognitive decline can be a sign of a more serious condition such as dementia or Alzheimer's.
Increased risk of social isolation and loneliness: This is especially common in those who have lost a spouse and/or have limited mobility.
Diet: Consuming a diet high in calories, sugar and unhealthy fats can also contribute to a slower metabolism. However, I tell my members these changes do not have to be permanent.
Tucker's Tips to Boost Metabolism
Eat enough protein: Protein takes more energy to digest than carbohydrates or fat, so including more protein in the diet can help boost metabolism. To help manage blood glucose better, eat protein first (e.g., salmon, then veggies; beef before potato) and don't eat carbs alone.
Build muscle and do regular exercise: Muscle is "metabolically active," burning calories even at rest and accounting for about 30% of total metabolic rate.7-9 I generally recommended moderate to intense physical activity for at least 150 minutes per week, spread out over at least three to five days. I'm challenging all of my members to gain 3 lbs. of muscle in 2023.
Perform bodyweight exercises: Three times per week – for only 30 minutes at a time – for 6-12 weeks can increase muscle mass by 3%.10 That may not sound like much, but if you recall the statistics, that's equivalent to what can be lost in an entire decade! Older adults who perform strength-training exercises can increase muscle mass up to a 44% in just 12 weeks.11
My minimum list of exercises includes Brugger's maneuver, march in place, arm movements, balance training, and something for fascia stretching. I frequently write exercise programs or refer patients to physical therapists / trainers to create safe and effective exercise plans.
Exercise can increase satiety by affecting hormones and neurotransmitters that regulate appetite. During and after exercise, the body releases endorphins, which can reduce feelings of hunger and increase feelings of pleasure. It also increases the release of the hormone peptide YY, which is known to suppress appetite.
Exercise can affect the way we perceive food and change the way the brain responds to food cues, making high-calorie foods less appealing and healthier foods more appealing. I have a full-time weight-loss coach in my office, and I see the positive impact on satiety by reducing body fat and increasing muscle mass.
In addition to protecting calorie-burning muscle mass, resistance training also has an acute beneficial effect on metabolic rate. A single bout of HIIT strength training can result in a small increase in excess post-exercise oxygen consumption (EPOC) – more commonly known as "the afterburn effect"– for 24-48 hours after exercise.12
Exercise is crucial for health span and longevity. It is the hack for "healthy everything."
Eat regularly: Eating small, frequent meals throughout the day can help keep metabolism running at a higher rate.13
Drink enough water: Staying hydrated can help boost metabolism.
Get enough sleep: Lack of sleep can slow down metabolism.
Manage stress: Chronic stress has been linked to a slower metabolism and decreased muscle mass. There are a number of apps available that promote mindfulness and relaxation.
Protect your patients' metabolism by preserving muscle mass through physical activity and consider recommending a DNA test so you can offer personalized tips.
- Elia M, Ritz P, Stubbs RJ. Total energy expenditure in the elderly. Eur J Clin Nutr, 2000;54 Suppl 3:S92-103.
- Roberts SB, Dallal GE. Energy requirements and aging. Public Health Nutr, 2005;8(7A):1028-1036.
- Vaughan L, Zurlo F, Ravussin E. Aging and energy expenditure. Am J Clin Nutr, 1991;53(4):821-825.
- English KL, Paddon-Jones D. Protecting muscle mass and function in older adults during bed rest. Curr Opin Clin Nutr Metab Care, 2010;13(1):34-39.
- Kortebein P, Ferrando A, Lombeida J, et al. Effect of 10 days of bed rest on skeletal muscle in healthy older adults. JAMA, 2007;297(16):1772-1774.
- Krogh-Madsen R, Thyfault JP, Broholm C, et al. A 2-wk reduction of ambulatory activity attenuates peripheral insulin sensitivity. J Appl Physiol, 2010;108(5):1034-1040.
- Nelson KM, Weinsier RL, Long CL, Schutz Y. Prediction of resting energy expenditure from fat-free mass and fat mass. Am J Clin Nutr, 1992;56(5):848-856.
- Elia M. Organ and Tissue Contribution to Metabolic Weight. In: Kinney JM, Tucker HN, eds. Energy Metabolism: Tissue Determinants and Cellular Corollaries. New York: Raven Press, Ltd., 1992:61-79.
- Zurlo F, Larson K, Bogardus C, Ravussin E. Skeletal muscle metabolism is a major determinant of resting energy expenditure. J Clin Invest, 1990;86(5):1423-1427.
- Egan B. "Muscle Matters." TEDx Talks, June 2014. www.youtube.com/watch?v=LkXwfTsqQgQ
- Kryger AI, Andersen JL. Resistance training in the oldest old: consequences for muscle strength, fiber types, fiber size, and MHC isoforms. Scand J Med Sci Sports, 2007;17(4):422-430.
- Paoli A, Moro T, Marcolin G, et al. High-intensity interval resistance training (HIRT) influences resting energy expenditure and respiratory ratio in non-dieting individuals. J Transl Med, 2012;10(1):237.
- "Dr Layne Norton: The Science of Eating for Health, Fat Loss & Lean Muscle." Huberman Lab Podcast #97, January 2023. www.youtube.com/watch?v=K4Ze-Sp6aUE