Why Do We All Lose Lean Muscle at Some Point During Our Lifetime?

There is a great deal of uncertainty in life but here are three things you can count on, taxes, muscle loss and death. The loss of muscle due to aging is known as sarcopenia. Research from the Nutrition, Exercise Physiology and Sarcopenia Laboratory at the USDA Human Nutrition Research Center on Aging in Boston as well as other research groups continue to demonstrate that you can build muscle at any age. On the flip side, however, you also start losing it around age 35 and the loss gets more pronounced as you enter the fifth and seventh decades of life. There are many reasons why we all lose muscle and here are five of them. The good news is this loss of muscle can be slowed by consistent, progressive strength training, just a few times a week, coupled with adequate sleep and protein intake.


Cross-sectional photo of upper thigh area showing sarcopenia. Manchester Metropolitan University.

  1. Muscle Loss from Aging. The key is to stay strong by staying active and to strength train consistently in your early years and then work at carrying that forward through your golden years. The average person will lose 0.5 – 1 pounds of lean muscle mass per year starting around age 35. Participants in the Baltimore Longitudinal Study on Aging (aged 20-92 yrs.) showed a slow loss of lean muscle until age 65, followed by a faster decline as they continued to age (Borkan and Norris, 1977). In addition, as we age we see a loss of important hormones such as testosterone in men and estrogen in women that play a big part in this muscle losing scenario.
  2. Muscle Loss from Inactivity. Aging is inevitable but inactivity can be controlled. More than 30% of Americans are inactive and only 5% of us exercise vigorously during the course of a given week. The old adage, use it or lose it, still applies. Your goal is simple – to prevent the loss of muscle, bone etc. you must overload and stress your muscles at least 2-3 times each week by strength training. Per Olaf Astrand, MD, who is considered one of the founding fathers of exercise physiology states it perfectly: “Given what we know about the health benefits of physical activity, it should be mandatory to get a doctor’s permission not to exercise.”
  3. Muscle Loss from Inadequate Protein Intake. As you age, some individuals take in fewer calories over the course of a day and in turn fall short of their daily protein needs to build lean muscle. Others fall into the category of getting enough or more than enough calories but their diet contains more carbohydrates and fats. As a rule of thumb, the Institute of Medicine recommends 0.8 – 0.9 grams of protein per kilogram of body weight. You can also aim for 15-20 grams of protein in each of your three meals. In a study at the Pennington Biomedical Research Laboratory, researchers followed subjects for 12 weeks. The volunteers had to eat nearly 1,000 extra calories a day over and above what they needed to maintain their body weight. Their diets consisted of 5%, 15%, or 25% of total calories from protein. The medium and high-protein groups gained muscle mass while the low-protein group lost muscle mass. If you’re coming up short in terms of daily protein intake – it will be very difficult to build lean muscle tissue even if you’re strength training on a regular basis.
  4. Muscle Loss from Lack of Sleep. This is the area where most people miss the boat. A lack of sleep can help you lose the muscle-building ball game, even if you’re getting the recommended protein intake and strength training. On average, a good 7-8 hours of uninterrupted sleep is important for your body to recover and grow. The problem is that most of us are not getting that on a regular basis. According to sleep expert, William Dement, MD, PhD, social pressures to work more have reduced our sleep time by 20% over the past century. Muscle repair happens during sleep, so by getting six hours or less a night you’re limiting your body’s natural production of growth hormone that among other things helps to stimulate protein synthesis and fosters the repair of tissue. Think of sleep as an added bonus, according to a 2004 study, people who slept less than six hours a night were almost 30% more likely to become obese than those who slept seven to nine hours. To help you sleep better try avoiding all caffeine products 6 hours prior to bed.
  5. Muscle Loss from too Much Cardio. You have to set the stage in order to build lean muscle and that means the body has to be in an anabolic state (i.e. “muscle building”). You need a surplus of calories and adequate protein in order to build muscle mass. When a person is doing hours of cardio each week, the odds are their body is in what is known as a catabolic state (i.e. “muscle break-down”). If they are constantly in a negative deficit, because of the valuable calories spent doing cardio, and by not taking in the needed amount of daily calories, the body will not have enough stored energy to actually build new muscle tissue. When you are trying to add muscle, remember to keep the cardio to a minimum. Also keep in mind that your strength sessions alone are catabolic in nature and you need to immediately get into an anabolic mind-set following your workout. One the easiest ways to do this is to have a whey protein drink as soon as possible post workout.


Borkan, GA, Norris AH. (1977). Fat redistribution and the changing body dimensions of the adult male. Human Biology 49:495-514.

Dement, W (1999). The Promise of Sleep. Dell Publishing.


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