What You’re Made of Matters
From Director of Health Alex Maples
Your ratio of muscle to fat isn’t just about looks. Body composition plays a pivotal role in how your body functions and how long (and well) you live. In fact, outside of not smoking, few factors impact your long-term health outcomes more.
There are two main levers we can pull to improve our body composition: 1. Build muscle. 2. Lose fat. Simple, not easy. We’ll get back to those levers soon, but first, a primer on why they’re so important.
Why Muscle Matters
Muscle isn’t just for athletes or bodybuilders. It’s a critical asset that protects your health and independence as you age. A “longevity organ.”
Here’s what the research has to say about it:
Lower All-Cause Mortality
A 2014 study in The American Journal of Medicine found that adults over 55 with higher muscle mass had a 20–30% lower risk of death over 10 years.Better Metabolic Health
Muscle is the primary storage site for glucose. A 2017 study in Diabetes Care found that each 10% increase in skeletal muscle index reduced insulin resistance by 11% and cut the risk of type 2 diabetes by 12%.Cardiovascular Protection
Muscle supports healthy cholesterol, blood pressure, and vascular function. A 2018 JACC: Heart Failure study showed a 25% lower risk of cardiovascular events in those with higher muscle mass.Bone Density & Fall Prevention
Muscle strengthens bone and stabilizes joints. Resistance training reduces fracture and fall risk by over 30%, especially in older adults.
Mental & Cognitive Health
More muscle is linked to lower depression and cognitive decline. Multiple studies show reduced risk of depression (20%) and cognitive impairment (30%) in those with greater muscle mass.
Use It or Lose It
Without intervention, most people begin to lose muscle mass as early as their 30s – typically at a rate of 0.5% to 1% per year. By 60, that decline accelerates to 1–2% annually, increasing the risk of weakness, frailty, and loss of independence.
But it’s not inevitable. Resistance training can not only prevent muscle loss – it can reverse it, even well into your 50s and beyond. Your body is capable of adapting at any age, as long as you give it the right signal and support.
Think of muscle as your health retirement account. The more you invest early, the more protected and resilient you’ll be later in life. And just like financial savings, it’s never too late to start making smart deposits.
Why Excess Body Fat Harms Health
Carrying excess body fat – especially visceral fat around your organs – raises your risk for nearly every major chronic condition:
Increased Mortality
A 2016 Lancet meta-analysis of 10 million+ people found each 5-point increase in BMI above 25 raised mortality by 31%.Heart Disease and High Blood Pressure
A 2017 Circulation study found each 1% increase in body fat raised CVD risk by 7%. Obesity raises hypertension risk by 65%.Metabolic Dysfunction
Excess fat impairs insulin sensitivity and spikes your risk of diabetes and metabolic syndrome. A 5 kg/m² BMI increase more than doubles your diabetes risk.Cancer Risk
Fat tissue drives inflammation and hormone disruption, which are linked to 13 types of cancer. Visceral fat specifically increases colorectal cancer risk by 25%.Mental Health & Cognition
Obesity increases the risk of depression (32%), anxiety (20%), and cognitive impairment (19%).
Joint and Respiratory Issues
Excess weight stresses joints and narrows airways, raising the risk for arthritis, sleep apnea, and asthma.
How to Improve Body Composition
Reduce Body Fat
Create a calorie deficit through a combination of dietary intake and movement.
Focus on nutrient-dense, protein-forward meals to stay full and preserve muscle.
Track progress with BIA scales or DEXA scans – not just weight.
Build Muscle
Stimulus: Resistance training (3–5x per week) is key to signaling your body to grow muscle.
Substrate: Aim for 0.6–1g of protein per pound of goal body weight daily.
Rest: Recovery allows muscles to rebuild stronger. Prioritize sleep and manage stress.
Bonus: If you're new to lifting, you may experience “body recomposition” – losing fat and gaining muscle simultaneously.
Where Should You Be?
While “optimal” varies by individual, here are general body fat ranges associated with good health:
Men: 10–20%
Women: 18–30%
Going too low (e.g., <10% for men, <18% for women) may suppress hormones and impair function – so leanness for the sake of leanness isn’t the goal. Sustainable health is.
How to Measure Your Body Fat
Knowing where you stand is essential for improving body composition. While there are many methods out there, the two most accessible and practical options are DEXA scans and BIA (bioelectrical impedance analysis) scales. Each has its pros and cons – understanding both will help you use them wisely.
DEXA Scan: The Gold Standard
What it is:
DEXA (Dual-Energy X-ray Absorptiometry) is a medical imaging scan that measures bone density, lean tissue, and fat mass with a high level of precision.
Pros:
Highly accurate: Margin of error is typically around 1–3%.
Regional data: Shows fat distribution (e.g., visceral vs. subcutaneous).
Includes bone density: Valuable insight for aging and injury prevention.
Cons:
Cost: Typically $50–$150 per scan.
Access: Must be done in a clinical or wellness setting.
Radiation: Very low dose, safe for periodic use but not for frequent tracking.
Best for: Establishing a reliable baseline 1–2 times per year.
BIA Scales: Convenient, but Often Underestimate
What it is:
BIA works by sending a small electrical current through the body and measuring the resistance. Since water-rich tissue (like muscle) conducts electricity well and fat doesn’t, the device estimates your body fat percentage based on conductivity.
Pros:
At-home convenience: Easy to use consistently.
Affordable: Many good options under $100.
Good for trend tracking over time with consistent conditions.
Cons:
Less accurate: Error margins range from 3–8% or more.
Underestimates BF%, especially in lean or muscular individuals.
Affected by hydration, food intake, and time of day.
Limited detection: Most home devices use only hands or feet, which can miss central fat stores.
Example: If your BIA scale says 12%, you might actually be closer to 15–17% depending on your muscle mass and hydration.
How to Use BIA Effectively
Despite its flaws, BIA can still be a valuable tool if you use it the right way:
Use it under consistent conditions: same time of day (ideally in the morning, fasted, and post-bathroom).
Track the weekly average, not individual daily readings.
Look for trends over time, not absolute values.
Pair with occasional DEXA scans to recalibrate your sense of what your scale is really showing you.
Closing Thoughts
Muscle supports everything from strength and mobility to mood and metabolism. Body fat, in excess, compromises them all. By improving your body composition, you're not just changing how you look (although when you feel good about how you look, you’ll perform better and have more confidence). You're investing in the duration and quality of your life for the long term.
