Starting at the age of 30, your muscle mass declines at a rate of 3-8% each decade. As you get older, the rate of muscle mass loss gets even faster, clocking in at 5-10% lost each decade after 50 years of age. This means that your lean body mass at age 70 will be8-12 kgs (17-26 lbs) less than at age 30.

Why is this a problem?

This is a problem in regards to your blood sugar regulation, your cholesterol levels, your risk of falls and fractures, your quality of life, your mental health, and your metabolism.

Your resting metabolic rate (how many calories you burn when at rest) declines at a rate of 2-3% per decade in adults. Remember how you could eat a Big Mac meal for lunch and a whole pizza for dinner in your teens and not gain a pound? But now, even getting within a city block of a cookie will make the scale tip? Part of this occurs because your resting metabolic rate is lower than when you were a teenager; your body as a grown adult needs less fuel to function.

To sum it up, the loss of your lean muscle mass is the greatest contributor to the age-related decline in resting metabolic rate. Said another way, the main reason why your metabolism suffers as you age is because you lose muscle.

One of the best treatment strategies for preventing further muscle loss, and building new muscle, is resistance training. Strength training should be part of every treatment plan starting at 30 years of age. Lean muscle can be increased by as much as 1.5 kg after 3 months of training 2-3 times per week. After a single bout of resistance training, your resting metabolism increases by as much as 5-9% for 72 hours.

Naturopathic doctors can ensure your strength-training program is efficacious. As we get older, we can become resistant to the signals of exercise. A plan that includes omega-3 fatty acids, vitamin D3 optimization, dietary protein adequacy, and branch chain amino acid (BCAA) supplementation make strength training even more effective.

Keep in mind, muscle mass is only one piece of a very complicated puzzle. Weight management is complex and needs a full body approach. A physician may also run blood work that assesses your stress, thyroid, and sex hormones.

References
Petroni ML, Caletti MT, Dalle Grave R, Bazzocchi A, Aparisi Gómez MP, Marchesini G. Prevention and Treatment of Sarcopenic
Obesity in Women. Nutrients. 2019;11(6):1302. Published 2019 Jun 8. doi:10.3390/nu11061302
Speakman JR, Selman C. Physical activity and resting metabolic rate. Proc Nutr Soc. 2003;62(3):621-634. doi:10.1079/PNS2003282
Stenholm S, Harris TB, Rantanen T, Visser M, Kritchevsky SB, Ferrucci L. Sarcopenic obesity: definition, cause and
consequences. Curr Opin Clin Nutr Metab Care. 2008;11(6):693-700. doi:10.1097/MCO.0b013e328312c37d
Westcott WL. Resistance training is medicine: effects of strength training on health. Curr Sports Med Rep. 2012;11(4):209-216.
doi:10.1249/JSR.0b013e31825dabb8