Episode 2 · Bone Health & Strength Training

Listen to the Wellness AF Club Podcast, Episode 2 | By Jen Stanley

In your 30s, the most useful thing you can do for your long-term health is to build bone density now so your skeleton can carry you through the next 50 years without fracturing every time you trip over your dog.

The short answer: lift heavy twice a week, eat enough protein, and cover your calcium and vitamin D. The rest of this article is why that works, what the studies say, and how to start safely.

Short on time? Jump to the TLDR or the FAQ.

Bone health is one of those topics that sounds boring until it becomes urgent, usually around the time someone’s mom breaks a hip and suddenly everyone’s Googling “how to prevent osteoporosis.” I don’t want that to be you. Or your mom. So let’s get into it.

First: your bones are living tissue that rebuilds itself constantly

Most of us picture bones as static structures, like a wooden frame inside your body. In reality, your skeleton is a living, constantly remodeling tissue. Right now, approximately 2 million cellular work crews are simultaneously tearing down old bone and building new bone throughout your body. So your entire skeleton turns over roughly every 10 years.

Two types of cells run this operation. Osteoclasts handle demolition, while osteoblasts handle rebuilding. Embedded throughout the bone matrix, meanwhile, are sensor cells called osteocytes, these detect mechanical load and signal the builders to get to work.

Here’s the mechanic that matters for everything else in this post: bones respond to strain. An orthopedic surgeon named Harold Frost figured this out in 1987 and called it the mechanostat theory. Think of it like a thermostat for your skeleton. Below a certain strain threshold, your body lets bone go, it doesn’t need it if nothing’s challenging it. Above the threshold, however, it builds. The problem is that threshold is higher than most exercise programs take you.

Why walking isn’t enough

The liftmor trial: the study that changed everything

If you take nothing else from this post, take this study. The LIFTMOR trial (Watson et al., 2018, Journal of Bone and Mineral Research) is the one I keep coming back to because it is so simple and so decisive.

Then there’s the EFOPS study, the longest controlled exercise trial for osteoporosis ever run. Kemmler et al. followed 137 early-postmenopausal women for 16 years, combining heavy resistance work, high-impact aerobics, and balance training four times a week. After 16 years, they saw a 58% reduction in fractures. That’s real broken bones avoided, the outcome that actually matters. That’s the goal.

The 3-year window you don’t want to miss

This is what keeps me up at night. The SWAN study, one of the most comprehensive longitudinal studies on women’s health ever conducted, tracking over 3,300 women for 20+ years, showed that bone loss doesn’t happen gradually or predictably. Instead, it happens in a cliff.

During early perimenopause, there is little to no measurable bone loss. Then, about one year before your final period, it starts. Losses accelerate through a 3-year window ending roughly 2 years after menopause. During that window, the SWAN data showed annual losses of 2.5% at the lumbar spine and 1.8% at the femoral neck. Over the full 3 years, that adds up to 7.4% of your spinal bone density gone. Roughly 25% of women are “fast bone losers” who can drop 10–20% in the 5–6 years surrounding menopause.

Importantly, SWAN researchers called this a “time-limited window of opportunity” for intervention. That 3-year window may account for nearly 40% of the total bone loss between menopause and age 80. After the rapid phase ends, loss slows to just 0.5–1% per year. But the damage from the cliff? You’re working with what’s left.

Dieting and bone loss: the thing nobody warns you about

If you listened to Episode 1, you know I’m a big proponent of a sustainable calorie deficit for fat loss. That approach is still solid, but there’s a piece of the picture I didn’t fully cover, and it connects directly to everything we’re talking about today.

Caloric restriction by itself reduces bone density. A meta-analysis by Soltani et al. (2016) confirmed that weight loss through caloric restriction alone causes measurable decreases in hip and lumbar spine BMD. Similarly, the CALERIE Phase 2 trial showed this even in relatively young, non-obese adults, just two years of moderate restriction caused significant bone losses at fracture-relevant sites.

And the more aggressive the deficit, the worse the damage. In people doing very-low-calorie diets or bariatric surgery, bone losses of 3–13% have been documented. One 2024 prospective study found 1-year BMD decreases of 3.5% at the spine, 5.2% at the femoral neck, and 8.1% at the total hip after bariatric surgery. So what’s the answer? Resistance training, specifically and consistently.

This is why in the framework from Episode 1, eat for weight loss, exercise for health, the strength training piece isn’t optional. It’s the thing that keeps your skeleton intact while the scale moves. So those two goals reinforce each other perfectly. That’s the system.

What about GLP-1 medications?

If you’re on semaglutide or tirzepatide, this section matters even more for you. A 2024 RCT found 52 weeks of semaglutide increased bone resorption and lowered BMD at multiple sites. In fact, the Wegovy FDA label includes an actual fracture warning. That said, a JAMA Network Open RCT showed that combining GLP-1 medication with structured exercise fully preserved BMD at the hip, spine, and forearm. Resistance training is doing the protecting. If you’re using these medications, lifting is not optional, it’s essential.

The nutrient lineup: beyond the calcium fairy tale

Everyone talks about calcium. And yes, you need it, 1,000 mg a day for most women under 50, and 1,200 after that. But calcium without the supporting cast is like building a house with only bricks and no mortar. Here’s what the research actually supports:

The protein myth I need to bust right now

You may have heard that eating too much protein leaches calcium from your bones. That’s the old “acid-ash hypothesis”, and it is thoroughly dead. A meta-analysis by Fenton et al. found zero relationship between acid excretion from protein and calcium balance (p=0.38, with 94% statistical power to detect an effect if one existed). As it turns out, the increased urinary calcium from higher protein comes from increased absorption in the gut, not from your bones releasing it. So eat your protein. Your bones will thank you.

DEXA scans: what your bone density numbers actually mean

A DEXA scan measures bone mineral density at your lumbar spine, femoral neck, and total hip. Practically speaking, it takes 10–20 minutes, is painless, and delivers about 1–15 microsieverts of radiation, equivalent to a few hours of background radiation just from being alive. Your results come back with two scores that matter very differently depending on where you are in life.

• T-score: Compares your BMD to a healthy 30-year-old woman. Normal is ≥ −1.0. Osteopenia falls between −1.0 and −2.5, while osteoporosis is ≤ −2.5. Notably, fracture risk roughly doubles with each 1 standard deviation decrease.
• Z-score: Compares you to other women your age, sex, and ethnicity. For premenopausal women, this is actually the more clinically relevant score. A Z-score of −2.0 or lower means you’re below the expected range and should investigate why.
• Always use the same machine. Measurement error between different DEXA machines can exceed actual biological change, so serial monitoring only means something when done on consistent equipment.
• Degenerative changes can inflate your numbers. Arthritis and bone spurs in the lumbar region can make your BMD look better than it actually is. Make sure your doctor is aware of these.

The USPSTF officially recommends routine DEXA screening starting at 65 (or earlier for postmenopausal women with risk factors). Some practitioners, however, recommend a baseline scan around age 35–40 to establish your personal reference point before perimenopause hits. That’s not yet standard guidance, but it makes a lot of sense, and it’s absolutely worth discussing with your doctor. Many imaging centers charge just $50–150 out of pocket.

What to actually do with all of this

Okay, you’ve got the science. Now let’s make it actionable. Here’s the framework that comes directly out of all this research:

• Lift heavy, at least twice a week. Compound movements, squat, deadlift, overhead press. Not light dumbbells. Not Pilates. Specifically, you want challenging loads where the last two reps feel genuinely hard.
• Add some impact work. Box jumps, skipping, and jump squats generate strain rates that lifting alone can’t replicate, and they’re specifically osteogenic for the hip.
• Eat enough protein. A minimum of 1.0–1.2 g per kg of bodyweight. Protein is literally the matrix that calcium mineralizes into, so you can’t build strong bone without it.
• Keep your deficit moderate. That means 500–750 calories below maintenance, not 1,200 and done. Aggressive restriction is bad for bone. (See Episode 1 for how to calculate yours.)
• Check your vitamin D. About 24% of US adults aged 40–59 are below 20 ng/mL. Because you can’t absorb calcium efficiently when you’re deficient, this matters more than most people realize. The 2024 Endocrine Society guidelines recommend 600 IU/day for most adults under 50, and more if you’re deficient.
• Consider a baseline DEXA in your late 30s or early 40s. You need to know where you’re starting before the perimenopause cliff hits.
• Don’t stop once you start seeing results. BMD gains reverse within months of stopping training. Consequently, this is a life habit, not a 12-week program.

Disclaimer: This content is for educational purposes only and is not medical advice. Always consult a qualified healthcare provider before beginning a new exercise program or making changes to your supplement routine, especially if you have or suspect a bone health condition.

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