Things to Remember
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The real problem isn't just being overweight - it's not having enough muscle. For decades, we've focused on losing fat and cutting calories, but this often causes people to lose muscle too, which actually makes your metabolism worse over time.
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Your muscles do way more than help you move - they're your body's main tool for managing blood sugar. About 80% of the carbs you eat get processed by your muscles. When you don't have enough muscle or it's not working well, your blood sugar rises and you're on the path toward diabetes.
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Muscle loss affects your brain health too. Your muscles produce protective factors that keep your brain healthy and may help prevent Alzheimer's and cognitive decline. People with low muscle mass show brain changes that look like early dementia - sometimes decades before symptoms appear.
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Most popular diets from the past 50 years have made things worse. When you cut calories without eating enough protein or doing strength training, you lose muscle along with fat. Then when you regain weight (which most people do), you gain back fat but not muscle - leaving you worse off than before.
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Being "skinny fat" is a real metabolic problem. You can have a normal weight on the scale but still be unhealthy if you have too much body fat and too little muscle. The number on the scale doesn't tell the whole story.
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This is fixable, but it requires a different approach. Focus on building and maintaining muscle through strength training and eating enough protein, not just on losing weight through cardio and calorie restriction.
This article explains why losing muscle as we age matters more than most people realize, what causes it to happen, and what you can actually do to prevent or reverse it.
There's a patient I think about sometimes when I'm reviewing someone's blood work. Mid-fifties, working professional, doing everything "right" - or at least, everything we've told people to do for the past fifty years. Counting calories. Avoiding fat. Walking daily. Following the food pyramid like scripture.
Muscle vs. Fat: What Each Tissue Actually Does for Your Metabolism
| Function | Skeletal Muscle | Body Fat (Adipose Tissue) |
|---|---|---|
| Glucose metabolism | Handles ~80% of glucose uptake; primary site of insulin-mediated glucose disposal | Minimal glucose uptake; becomes insulin resistant when excessive |
| Metabolic rate | High metabolic activity; increases basal metabolic rate significantly | Low metabolic activity; minimal calorie burn at rest |
| Protein storage | Stores amino acids for immune function, wound healing, hormone production | No protein storage capacity |
| Inflammatory signaling | Secretes anti-inflammatory myokines (irisin, IL-6, BDNF) | Secretes pro-inflammatory adipokines when excessive (TNF-α, IL-6) |
| Brain health | Produces BDNF (brain-derived neurotrophic factor) supporting cognition | No direct neuroprotective effects |
| Disease protection | Higher muscle mass associated with lower risk of diabetes, dementia, mortality | Excess fat mass increases risk of metabolic disease, cardiovascular disease |
| Aging resilience | Protects against sarcopenia, falls, fractures, functional decline | Excess accumulation accelerates metabolic aging |
| Response to calorie restriction | Easily lost during dieting without adequate protein and resistance training | Primary target for healthy weight loss |
And declining anyway.
Not dramatically. Just... steadily. A little more tired each year. A little less steady on the stairs. Blood sugar creeping up despite eating less. The kind of slow fade we've learned to call "normal aging."
Except it's not normal. And it's not inevitable. We've just been measuring the wrong thing.
The Obesity Paradox That Isn't
For decades, we've fought obesity like it's the primary disease. Billions in research funding, entire medical subspecialties, endless diet programs - all focused on fat loss. And yet metabolic disease keeps rising. Diabetes keeps rising. Cognitive decline keeps rising.
Maybe because we've been trying to fix the wrong problem.
The real issue isn't just having too much fat. It's having too little muscle. Or more precisely - having muscle that's metabolically broken, undernourished, underused. I see people in their forties and fifties who've spent years on calorie-restriction diets, losing weight but also losing the one tissue that actually keeps them metabolically healthy.
They end up "skinny fat" - normal BMI, but with body composition that tells a different story. High body fat percentage despite low weight. Minimal lean mass. Metabolically, they're in trouble. But we celebrate the number on the scale.
What Muscle Actually Does (Beyond Looking Good in a Tank Top)
Most people think muscle exists for movement and aesthetics. It does those things, sure. But that's like saying your liver exists to make bile - technically true, but missing about 500 other critical functions.
Muscle is your largest metabolic organ. It handles roughly 80% of glucose uptake - meaning most of the carbohydrates you eat get processed by skeletal muscle, not by your pancreas or liver. When muscle becomes insulin resistant or there's simply not enough of it, glucose has nowhere to go. Blood sugar rises. Insulin rises. The cascade toward type 2 diabetes begins.
But glucose disposal is just the beginning.
Muscle also stores amino acids - the building blocks for immune function, wound healing, hormone production. When you're sick or injured, your body breaks down muscle to access those amino acids. If you don't have much muscle to begin with, recovery becomes harder. Infections last longer. Wounds heal slower.
Muscle secretes myokines - signaling molecules that reduce inflammation, improve brain function, regulate metabolism. Some of these myokines (like irisin) even help convert white fat to metabolically active brown fat. Others (like brain-derived neurotrophic factor, or BDNF) support neuroplasticity and may protect against cognitive decline.
So when someone is "under-muscled" - and most people in Western societies are - they're not just weak. They're metabolically compromised. Their glucose regulation is impaired. Their inflammatory tone is elevated. Their cognitive reserve is reduced.
We've been treating this as a cosmetic issue. It's not. It's a physiological crisis.
The 50-Year Mistake
Here's what happened, roughly speaking.
In the 1970s and 80s, we decided fat was the enemy. Dietary fat, body fat - all bad. The solution: eat less, move more, focus on cardio. The food pyramid emerged. Low-fat everything. Carbohydrate-heavy diets became standard advice.
And people got fatter. And sicker.
Not because they weren't trying. They were trying. They were following the guidelines. But the guidelines ignored muscle.
When you restrict calories without adequate protein and resistance training, you lose weight - but much of that weight is muscle. Your basal metabolic rate drops. Your insulin sensitivity worsens. You become "metabolically obese" even if you're not overweight by BMI standards.
Then you regain the weight (because metabolic rate has dropped and hunger hormones are dysregulated), but you regain it as fat, not muscle. Each diet cycle leaves you with worse body composition than before.
This is sarcopenic obesity - high fat mass, low muscle mass - and it's metabolically devastating. It's associated with insulin resistance, cardiovascular disease, cognitive decline, frailty, all-cause mortality.
We created it. With our advice.
The Alzheimer's Connection (And Why It Terrifies Me)
One of the most striking things about muscle loss isn't immediately visible on the outside.
It's what happens to the brain.
Muscle and brain health are intimately connected. Partly because muscle produces BDNF and other neuroprotective factors. Partly because muscle insulin sensitivity affects brain glucose metabolism (and the brain is an extraordinarily glucose-hungry organ). Partly because physical activity - particularly resistance training - improves cerebral blood flow and neurogenesis.
When someone is chronically under-muscled, their brain suffers. We see this in brain imaging studies: reduced hippocampal volume, impaired glucose metabolism in key brain regions, patterns that look like early Alzheimer's disease.
Sometimes decades before symptoms appear.
I think about the patient I mentioned earlier. Fifty-five years old. Brain scan showing early Alzheimer's changes. Not because of genetics (no family history). Not because of obvious risk factors (normal cholesterol, normal blood pressure). But because of decades of muscle loss and metabolic dysfunction that nobody had noticed or addressed.
Could it have been prevented? Maybe. Maybe not entirely. But muscle health would have given her brain a fighting chance.
Protein: The Forgotten Macronutrient
If muscle is the forgotten organ, protein is the forgotten macronutrient.
Current dietary guidelines suggest 0.8 grams per kilogram of body weight per day. That's enough to prevent deficiency - barely. It's not enough to build or maintain muscle, especially as you age.
After about age 30, you develop "anabolic resistance" - your muscles become less responsive to protein. You need more stimulus (more protein, more resistance training) to achieve the same muscle protein synthesis. This accelerates after 50.
Most people don't adjust. They continue eating the same amount of protein they ate at 25. Or less, if they're trying to lose weight.
The result: progressive muscle loss. Sarcopenia. Frailty. Metabolic decline.
Current research suggests older adults need at least 1.2 to 1.6 grams per kilogram per day. Athletes and people doing serious resistance training may need even more. And it matters when you eat it - muscle protein synthesis peaks after a meal containing 25-40 grams of high-quality protein.
But most people don't know this. They have a carb-heavy breakfast (toast, cereal, juice). A salad for lunch (maybe 10 grams of protein). Then a decent dinner with some protein, but by then it's too late - you can't "catch up" muscle protein synthesis at the end of the day.
Three meals with adequate protein is better than one large protein meal. Distribution matters.
Resistance Training: The Intervention We're Not Prescribing
If I could prescribe one intervention that improves metabolic health, bone density, cognitive function, mood, longevity, and quality of life - it would be resistance training.
Not cardio. Not yoga. Not walking (though all of those have benefits).
Resistance training.
It's the only intervention that directly builds muscle. And muscle, as we've established, is the metabolic foundation of health.
Yet most doctors don't prescribe it. They prescribe statins, metformin, antidepressants. All useful medications in the right context. But none of them build the metabolic infrastructure that prevents disease in the first place.
Resistance training does.
It improves insulin sensitivity - often dramatically. Some studies show effects comparable to metformin. It increases bone mineral density, reducing fracture risk. It improves balance and coordination, reducing fall risk (which, in the elderly, is a leading cause of death). It releases myokines that reduce systemic inflammation.
And it doesn't require a gym membership or fancy equipment. Bodyweight exercises, resistance bands, dumbbells - all effective. The key is progressive overload: gradually increasing resistance over time to stimulate muscle growth.
But we don't teach this in medical school. At least, not in mine. We learned about sarcopenia as something that happens to very old or hospitalized patients. We didn't learn about it as a preventable, treatable condition affecting millions of middle-aged people right now.
The Muscle-Centric Paradigm Shift
What if we stopped focusing on weight loss and started focusing on muscle health?
What if the goal wasn't "lose 20 pounds" but "gain 5 pounds of muscle"?
What if we measured body composition routinely - not just BMI, but lean mass, fat mass, metabolic health markers?
What if we prescribed protein and resistance training as first-line interventions for metabolic disease?
This isn't theoretical. It's already happening in pockets of medicine - sports medicine, geriatrics, some forward-thinking primary care practices.
But it needs to become standard of care.
Because the current approach isn't working. Obesity rates keep rising. Diabetes rates keep rising. Dementia rates keep rising. We're losing ground, not gaining it.
Maybe because we've been fighting the wrong battle.
What This Means Practically
If you're reading this and thinking "okay, but what do I actually do?" - here's what the evidence suggests:
On protein:
- Aim for 1.2 to 1.6 grams per kilogram of body weight per day
- Distribute it across three meals, not one
- Prioritize high-quality sources (meat, fish, eggs, dairy, legumes)
- For a 70 kg person, that's roughly 85-110 grams per day
On resistance training:
- At least twice per week, ideally three to four times
- Focus on major muscle groups (legs, back, chest, core)
- Progressive overload - gradually increase weight or resistance over time
- Form matters more than load; don't sacrifice technique for heavier weights
On body composition:
- Don't rely on BMI alone. Get a DEXA scan or bioimpedance analysis if possible.
- Track lean mass, not just total weight
- Losing weight is only good if you're losing fat and preserving (or gaining) muscle
On aging:
- The earlier you start building muscle, the better
- But it's never too late - muscle responds to resistance training even in your 80s
- Think of muscle as your "longevity organ"
The Uncomfortable Truth
We got it wrong. For fifty years.
Not maliciously. With good intentions, actually. But wrong nonetheless.
We told people to eat less and move more, without specifying what to eat or how to move. We focused on fat loss without protecting muscle. We celebrated weight loss even when it came at the expense of metabolic health.
And now we have generations of people who are metabolically fragile - under-muscled, insulin resistant, inflamed, declining.
Some of them are my age. Some of them younger.
The good news: muscle responds. At any age. With the right stimulus (protein, resistance training, consistency), you can build muscle, improve metabolic health, reduce disease risk.
The uncomfortable news: it requires effort. Resistance training is hard. Eating adequate protein requires planning. It's not a quick fix or a magic pill.
But it works. And unlike most interventions in medicine, it has almost no side effects and massive upside.
I still think about that patient sometimes. The one with early Alzheimer's changes at fifty-five. I wonder if things would have been different if we'd paid attention to her muscle health twenty years earlier.
Maybe. Maybe not.
But I know this: we can't keep ignoring muscle and expecting people to age well. It's not working. It's never worked.
Time to try something different.
What do you make of all this?
