High SHBG and Low Free T: Why "Normal" Testosterone Labs Don’t Always Mean You're Fine
What men need to know about the hormone that’s quietly hijacking their free testosterone—and how to fix it.
When the Labs Look Fine But You Don’t Feel Fine
One of the more frustrating scenarios I see with clients—especially active guys—is when they’ve got textbook “normal” testosterone numbers on paper, but they’re dragging through workouts, motivation is low, libido has tanked, and recovery feels like molasses.
In many of these cases, the problem isn’t how much testosterone they’re making—it’s how much is actually usable. That’s where SHBG comes in.
SHBG 101: The Protein That Locks Up Your Testosterone
Sex hormone-binding globulin (SHBG) is a protein made in your liver that binds tightly to sex hormones like testosterone and estrogen. When testosterone is bound to SHBG, it’s basically on lockdown—it can’t get into cells and do its job (Anderson, 1974).
Here’s the breakdown:
Total testosterone = bound + unbound (everything in your bloodstream)
Free testosterone = the tiny portion (~2–5%) that’s bioactive and unbound
Bioavailable testosterone = free T + the portion loosely bound to albumin (another protein)
The problem? If SHBG is high, it soaks up more of your testosterone, leaving less free T to circulate—even if your total T looks perfectly fine on your lab report. Symptoms of low free T can include:
Low sex drive or fewer morning erections
Fatigue or low motivation
Sluggish recovery from training
Difficulty building strength or muscle
Mild mood dips or brain fog
This is what’s often referred to as functional hypogonadism—the hardware is there, but the signal isn’t getting through.
I’ve worked with so many clients who were told, “Your testosterone looks great,” while they continued to feel flat. High SHBG was often the missing piece.
Client Story: Fixing It in Real Time
One client—call him Matt—was a 35-year-old triathlete with a full-time desk job and a meticulous routine. His training was structured, his nutrition dialed, and his Whoop data always impressive. But something wasn’t adding up. He came to me feeling drained, flat, and increasingly disconnected from the "high-performer" identity he’d built. Recovery lagged, sex drive was down, and his motivation in both work and training was fading.
Labs showed total testosterone at 675 ng/dL. His primary care doctor said everything looked great. But SHBG was 88 nmol/L. After crunching the numbers, free testosterone came out well below the functional range. We had our answer.
We worked together to rebalance things. First, we added calories—especially around training sessions—and increased carbohydrate intake. We made some small tweaks to his training to build in more recovery and reduce the constant physiological demand. We also included a very basic supplement stack: 6 mg boron daily, magnesium glycinate in the evenings, and a bit of vitamin D.
Eight weeks in, Matt’s SHBG had dropped to the low 60s, and his free T improved significantly. But more than the numbers, his energy was back. He described it as feeling “like I’ve shifted back into a gear I thought I didn’t have anymore.” SHBG tends to be high in metabolically healthy, lean individuals. Low insulin—often a good thing—removes the inhibition on SHBG production. So the very traits that signal good health can, paradoxically, suppress bioavailable testosterone.
Add in endurance training, low-carb diets, fasting, or high training volumes without matching energy intake, and SHBG climbs even higher. It’s a super common profile among those chasing leanness and performance, but not always conducive to optimal hormone function.
Why SHBG Goes Up—Especially in Lean, Active Men
SHBG production is influenced by multiple factors:
Insulin lowers SHBG – Very lean or low-carb individuals often have low insulin, which can inadvertently drive SHBG up.
Thyroid hormone raises SHBG – Slightly overactive thyroid or excessive thyroid meds can increase SHBG.
Estrogen raises SHBG – Even in men, elevated estrogen (from body fat or exogenous sources) can play a role.
Liver health matters – Since SHBG is made in the liver, anything affecting liver function—like fatty liver or alcohol—can shift SHBG levels (MedlinePlus).
And here’s what’s counterintuitive: the fitter you are, the more likely your SHBG is high. Low body fat, clean eating, high training volume, low fasting insulin—all of that is great for general health, but it can subtly tank your free testosterone.
In fact, a 2022 study on college athletes found that 80% had low free T despite normal total T, with high SHBG and low insulin as the key culprits (Turner et al., 2022). I’ve seen similar lab profiles in endurance athletes and high-performing executives who train hard and eat clean.
How to Know If This Is You
If you’ve got symptoms but normal total T, ask your doctor for:
Total testosterone (drawn in the morning)
SHBG
Albumin (or use a standard value like 4.3 g/dL)
Then plug the numbers into a free testosterone calculator (like the ISSAM one online). You might be surprised by how little free T you actually have.
What to Do If High SHBG Is the Problem
In my practice, I’ve seen clients rebound by making targeted changes that bring SHBG down and free T up—without jumping straight to medication. Here's where we usually start:
1. Eat Enough—Especially Carbs
Chronic underfueling or strict low-carb diets can suppress insulin and elevate SHBG. For highly active clients, I often recommend a strategic increase in carbs, especially around workouts. The difference in energy and recovery is often immediate.
2. Taper the Training Load
Too much volume—especially endurance or high-intensity work—can suppress reproductive hormones and elevate SHBG. If recovery is suffering, dialing back intensity or adding deloads can be a game changer.
3. Evaluate Thyroid Function
Even slightly elevated T3/T4 can bump up SHBG. If you’re feeling hot, anxious, or overly revved up—or are on thyroid meds—it’s worth looking into.
4. Consider Targeted Supplementation
Boron (3–6 mg/day): Some evidence supports its ability to lower SHBG and increase free T (Naghii et al., 2011).
Vitamin D, zinc, magnesium: Foundational micronutrients for hormone support.
Ashwagandha or fenugreek: May support testosterone and reduce SHBG in some individuals.
These aren’t magic pills, but when paired with other strategies, they can make a difference.
5. Work With a Clinician If Needed
In cases where lifestyle changes don’t cut it, a practitioner might explore:
Clomiphene citrate: To stimulate natural T production
TRT: For men with persistently low free T and classic symptoms
Root cause work: Addressing liver function, thyroid status, or nutritional gaps
The Bottom Line
If your symptoms suggest low testosterone but your labs say otherwise, don’t stop at total T. SHBG might be quietly tying up your hormones and leaving you with low T symptoms.
The good news here is that for many guys, it’s fixable. More food, better recovery, smarter training, and some targeted bloodwork can help get your free T—and your energy—back on track.
This is one of those sneaky issues I catch often in client labs. If you’re not feeling like yourself, don’t settle for “normal” total testosterone numbers until you’ve looked deeper.
References
Anderson, D. C. (1974). Sex-hormone-binding globulin. Clinical Endocrinology, 3(1), 69–96.
MedlinePlus. SHBG test – Sex hormone binding globulin. U.S. National Library of Medicine. https://medlineplus.gov/lab-tests/shbg-sex-hormone-binding-globulin/
Turner, T. W., et al. (2022). Hormonal profiles in collegiate male athletes: Free testosterone is often low despite normal total testosterone. Journal of Strength and Conditioning Research.
Naghii, M. R., et al. (2011). Comparative effects of daily and weekly boron supplementation on serum levels of testosterone and inflammatory biomarkers. Journal of Trace Elements in Medicine and Biology, 25(1), 54–58.
What Else I’m Reading
“Does the pre‑exhaustion method influence resistance training outcomes? A systematic review and meta-analysis” (SportRχiv, 2025)
This meta-analysis pooled results from trials comparing pre‑exhaust (single-joint exercise before multi-joint movement) versus traditional resistance training, focusing on measures like muscle strength, hypertrophy, and body composition. In healthy adults, the pre‑exhaust approach yielded broadly similar outcomes to traditional training: strength gains and hypertrophy were comparable, while body composition changes (e.g., fat mass) showed negligible differences.
📌 Takeaway: Pre‑exhaustion isn’t the game-changer some claim it is—it produces results similar to traditional training for most healthy adults. It might offer nuanced benefits in very specific scenarios, but muscle and strength development don’t seem to rely on its inclusion—so use it as a tool, not a necessity.
“Effects of strength training on quality of life in pregnant women: A systematic review” (Redondo-Delgado et al., 2025)
This systematic review examined published studies on strength training interventions during pregnancy—comparing them to no structured exercise—focusing on outcomes like maternal weight gain, low back/sciatic pain, mood, and health-related quality of life. Across the studies, strength training consistently reduced excessive gestational weight gain, alleviated back and sciatic discomfort, improved mood, sleep quality, energy levels, physical strength, flexibility, and overall health-related quality of life.
📌 Takeaway: Introducing structured strength training during pregnancy can offer multifaceted benefits—from easing pain and enhancing mood to boosting daily physical function and well-being. It continues to prove a safe, effective complement to prenatal care.
“Human skeletal muscle possesses both reversible proteomic signatures and a retained proteomic memory after repeated resistance training” (Hulmi et al., 2025)
In this 30-week study, untrained adults completed 10 weeks of lifting, 10 weeks off, and then 10 more weeks of retraining. Muscle biopsies showed some proteins returned to baseline after detraining—mostly those tied to metabolism—while others stayed elevated even after time off. These retained proteins, including calpain-2, suggest a molecular “memory” that helps muscle re-adapt faster the second time around.
📌 Takeaway: Your muscles actually remember your training. Some molecular changes from lifting persist even after weeks off, helping explain why getting back in shape is usually faster than starting from scratch.
Before you go 💬
I started writing because I kept having conversations that didn’t quite fit into a session or an Instagram post. If you’re thinking through something—training, nutrition, mindset, whatever—or just want to share what’s been working for you, hit reply. I read everything, and I’m always open to talking through it.