Many of us are drawn to efforts to improve our personal health (or the health of a loved one) by the lure of weight loss; given the fact that roughly a third of Americans are obese by typical measurement standards, weight loss is an appropriate and worthy goal.
What we should be more focused upon, though, is optimizing our lean body mass, given the almost astounding benefits optimal lean body mass provides.
Granted, weight loss and optimizing lean body mass are kissing cousins and very closely intertwined, though there are subtle (and some not so subtle) differences in approach and practice between the two.
Why bother with the distinction? The answer is easy – there are some extreme approaches to weight loss (and long term food plan choices) that compromise, some significantly, lean body mass and therefore general health and well-being over the long haul. Getting and staying optimally healthy and functional is of course the objective, and the road to get there is in reality pretty conceptually simple to navigate.
It’s worth thinking a bit more about lean body mass and its benefits…
What is Lean Body Mass?
Lean body mass is term used quite frequently these days by folks from all across the health and wellness spectrum. The simplest definition for Lean Body Mass (LBM) is the weight (mass) of everything in your body minus/without the various types of body fat stored on your frame.
LBM is sometimes (incorrectly) used interchangeably with muscle mass, and while they’re correlated strongly, of course LBM includes the weight of all “the other stuff” in our bodies beside muscle tissue – our skeletal structure, skin, internal organs, nervous system, the various fluids circulating through the system. There are a number of tools that are able to more accurately measure body composition and sort out with much greater precision your muscle mass, such as DEXA scans (duel-energy X-ray absorptiometry and BIA (bioelectrical impedance analysis).
Higher Lean Body Mass Implies Enhanced Function (and Function is the Ultimate Goal)
Life is about function – engaging fully and productively with your environment – and to do so optimally implies an intact and fully functional lean body mass. In particular, engaging fully functionally with our environment implies consistent, high-level function of our musculoskeletal system (muscles and joints aren’t necessarily designed to wear to failure in our sixties), and all the organ mass that supports their mobility-centric activities (heart, gut, liver, brain and neural tissue, etc.)
Excessive fat (adipose) mass is an unwelcome traveler along for the ride, a lumpy mass of nutrient storage far, far beyond rational possible needs, dampening the actions of homeostasis-seeking hormones (i.e. insulin resistance, decreased leptin signaling), overloading joints, driving inflammation, invoking frustration, shame, and anguish, and much more.
Lean Body Mass Promotes Insulin Sensitivity
The plague of insulin resistance carries with it a host of metabolic consequences, though it’s been a well-documented and long-accepted fact that a higher lean body mass is associated with lower rates of what many term prediabetes and insulin resistance. It’s well established that increasing insulin sensitivity is good, and insulin resistance is bad; we’ll delve more into insulin resistance later.
Try a quick search engine query of “lean body mass and insulin resistance” and you’ll find a flood of studies completed over the past several decades; we’ll look in detail at several in a later post.
Higher Lean Body Mass Increases Longevity
Observational studies such as this one have demonstrated conclusively that higher muscle mass (a strong correlate of LBM) in older adults is associated with lower all-cause mortality. Lower skeletal muscle mass and abdominal obesity (implying low lean body mass) has been shown to correlate strongly with higher all-cause mortality and cardiovascular mortality.
Lean Body Mass Strengthens Bones
Osteoporosis, in lay terms often referred to as thinning of the bones in the body, is a bone disease that occurs when the body makes too little bone, loses too much bone, or a combination of the two. (The word osteoporosis actually means “porous bone”.) Osteoporosis in it’s worst forms leads to a plethora of fractures (femur, wrist, and spine among the more common and serious), requiring at times aggressive intervention, and inducing impressive losses in the functional realm.
Bones in our bodies constantly remodel and change in response to a variety of factors, one of the more critical being mechanical stress – the kind of stress that is delivered by weight-bearing movement and stress in particular, movement and stress that is driven by our lean body mass/muscle tissue.
Lean Body Mass Serves as a Reserve in Times of Illness and Injury Stress
Many of us, during our lifetimes, will encounter on one level or another an event or catastrophe in the form of illness or injury that serves as a serious, maybe even life-threatening stressor.
I spent the first years of my medical career caring for individuals who had suffered some of the most catastrophic, survivable insults to health imaginable – spinal cord injuries, multi-system and/or widespread orthopaedic trauma, severe burns, traumatic brain injuries, progressive neuromuscular diseases, and strokes. Despite a careful, intensive, multidisciplinary approach to care, more often than not, during these times of severe stress, some degree of lean body mass loss was noted as bodies reached for every available resource at their disposal to recover.
Breaking down muscle mass, among other healthy tissues, to support recovery in these situations isn’t optimal, but can be life saving in a crisis. And lean body mass can be rebuilt too.
Lean Body Mass Increases Metabolic Efficiency
Having a higher LBM clearly improves metabolic efficiency, though I should clarify what I mean here by metabolic efficiency (which implies a host of meanings pending context and author).
Perhaps the best example is that of a carb-dependent (CD) versus a fat-adapted (FA) marathoner. Our CD runner will burn through liver and muscle glycogen stores fairly early in their race, necessitating loading the gut with more carbs (a potentially problematic issue in and of itself), followed by an insulin spike to combat the flood of carbohydrate into the bloodstream, with the body then utilizing the glucose to generate energy, though that process is metabolically “dirty”, producing a host of oxidation by-products.
Our fat-adapted runner, hydrating with water or electrolytes, has built the much more efficient metabolic machinery to burn fats, and without any exogenous fuels, even the thinnest, fittest runners carry thousands of calories in storage with them wherever they run, pulling fats out of storage and utilizing more efficient cellular machinery (FA folks have happier and more functional mitochondria) to keep the fires stoked throughout a race event. The FA athlete, by utilizing fats which offer more than twice the calories of energy produced than glucose – roughly 9 Cal/gram in fats vs. 4 Cal/gram in glucose – has a distinct advantage.
Lean body mass can be “trained” to burn fats (and ketones) very efficiently; fat mass doesn’t.
Tomorrow’s Foundation Post will look at how excess body fat isn’t your friend.
Leave a Reply