How to Increase SHBG Levels Naturally and Why It Matters

Sex hormone-binding globulin, commonly called SHBG, acts as a traffic controller for testosterone and estradiol in your bloodstream, and raising it through lifestyle changes can meaningfully lower your risk of type 2 diabetes and metabolic syndrome. SHBG is a protein made by your liver that binds to sex hormones and regulates how much of them is freely available to your tissues. When SHBG runs low, the balance tips toward excess free androgens and metabolic trouble. The good news is that several everyday factors, from what you eat to how much you weigh, directly influence how much SHBG your liver produces.

What SHBG Actually Does

SHBG is a protein that latches onto testosterone and estradiol with high affinity and ferries them through your blood. Its concentration in your plasma is a major factor in determining how much of those hormones floats around in a “free” state versus a protein-bound state.¹ Think of it like a sponge: when SHBG is abundant, more sex hormones are soaked up and unavailable to act on tissues. When SHBG is scarce, more hormones roam free. That distinction matters because it is free testosterone and free estradiol that actually enter cells and drive biological effects. The balance between SHBG-bound and unbound hormones shifts depending on how much SHBG your liver puts out, which in turn depends on insulin levels, body fat, diet, thyroid function, and your genes.

Why Low SHBG Is a Red Flag

Low SHBG is not just a lab curiosity. It consistently shows up as a predictor of serious metabolic problems. In a large prospective study published in the New England Journal of Medicine, people in the highest quarter of SHBG levels had roughly a 90 percent lower odds of developing type 2 diabetes compared to those in the lowest quarter, and the relationship held in both women and men. The researchers used genetic analysis to suggest this is not just a correlation; SHBG may play a causal role in diabetes risk.² Low SHBG also tracks closely with metabolic syndrome. In a study of men, those in the bottom quarter for SHBG were roughly twice as likely to have metabolic syndrome as those in the top quarter, even after accounting for traditional cardiovascular risk factors and insulin resistance.³

For women with polycystic ovary syndrome (PCOS), the picture is especially relevant. SHBG is considered a biomarker of the metabolic abnormalities that accompany PCOS, and low levels are tied to insulin resistance and the excess androgen activity that drives many of the syndrome’s symptoms.⁴ When SHBG drops, more free androgen circulates, which can worsen ovarian dysfunction, acne, and excess hair growth.⁵ Research in adolescents with PCOS confirms the pattern: SHBG levels are significantly lower than in age-matched controls.⁶

The Insulin Connection

If you want to understand what suppresses SHBG more than almost anything else, the answer is insulin. Your liver makes SHBG, and high circulating insulin directly puts the brakes on that production. A population study in Sweden found a strong inverse relationship between fasting insulin levels and SHBG. People with type 1 diabetes, who produce little or no insulin of their own, had significantly higher SHBG than people with type 2 diabetes, whose bodies tend to overproduce insulin in response to resistance.⁷ Longitudinal data backs this up: SHBG and insulin resistance move in opposite directions over time in men, premenopausal women, and postmenopausal women alike.⁸

This is the thread connecting most of the lifestyle strategies below. Anything that lowers insulin resistance or reduces circulating insulin tends to push SHBG upward. Anything that drives insulin higher tends to pull SHBG down. The liver reads insulin levels almost like a dimmer switch for SHBG production.

Losing Weight

Weight loss is the single most reliable lever for raising SHBG if you are carrying excess body fat. In a study of abdominally obese men placed on a very low-calorie diet, SHBG nearly doubled during the weight-loss phase, rising from about 28 to 48 nmol/l. It settled back somewhat during weight maintenance but still stayed meaningfully above the starting point.⁹ A separate analysis in both women and men confirmed that weight loss increased both SHBG and insulin sensitivity.¹⁰

The relationship between SHBG and body weight is not perfectly symmetrical, though. In weight-stable men, SHBG tends to drop by about 0.2 nmol/l for every one-unit rise in BMI. But during active weight loss, SHBG rises faster: about 0.43 nmol/l per unit decrease in BMI. The researchers noted that the tight link between SHBG and insulin was preserved throughout the process, reinforcing the idea that insulin is the central mediator.¹¹ In practical terms, you do not need to crash-diet. Moderate, sustained fat loss is enough to shift the needle on SHBG, and maintaining the weight loss preserves at least some of the gain.

Cutting Back on Sugar

The liver’s decision to make SHBG depends heavily on a transcription factor called HNF-4α. Simple sugars, both glucose and fructose, suppress HNF-4α by kicking off fat production inside liver cells. When the liver is busy converting sugar into fat, HNF-4α levels fall and SHBG production slows down.¹² This mechanism was initially demonstrated in lab settings, and subsequent work has confirmed that dietary sugars impair SHBG synthesis in the liver.¹³ The same pathway is described in a broader review of how hormones and nutritional factors control SHBG gene expression: monosaccharides effectively reduce SHBG expression by driving lipogenesis and lowering HNF-4α.¹⁴

The practical takeaway is that diets high in added sugars, sweetened beverages, and refined carbohydrates can suppress your SHBG beyond what body weight alone would predict. Fructose gets particular attention because it is processed almost entirely in the liver, right where SHBG is made. If you are trying to push SHBG up, cutting sugary drinks and ultra-processed sweets is one of the lowest-hanging-fruit interventions (pun intended).

Dietary Fat and SHBG

The type and amount of fat in your diet also appears to matter. In a small controlled feeding study, switching from a high-fat diet (more than 100 grams of fat per day) to a low-fat diet (less than 20 grams per day) for two weeks led to a significant increase in SHBG. The high-fat phase had done the opposite, lowering SHBG. The rise in SHBG on the low-fat diet was accompanied by a drop in free testosterone.¹⁵

That study used extreme dietary conditions, so you do not need to go ultra-low-fat to see a difference. But the direction of the effect is clear and consistent with the mechanism: excess fat in the liver interferes with the same HNF-4α pathway that sugar disrupts. A diet that keeps both sugar and saturated fat moderate, something resembling a Mediterranean-style pattern, aligns with the conditions under which SHBG production does best.

Coffee

Coffee drinkers tend to have somewhat higher SHBG, and the effect seems tied to caffeine rather than other compounds in the bean. In a study of postmenopausal women, those who drank four or more cups of caffeinated coffee per day had SHBG levels averaging about 27 nmol/l compared to 23 nmol/l among non-drinkers. Decaffeinated coffee and tea showed no such association.¹⁶ A large cross-sectional analysis of US health professionals found that drinking four or more cups daily was associated with about a 5 percent higher SHBG level.¹⁷

A randomized controlled trial attempted to test this more directly but was too small to draw firm conclusions; its results did not show a consistent effect of caffeinated coffee on SHBG.¹⁸ The observational data is fairly consistent, though, and given coffee’s other metabolic benefits, it is a reasonable habit if you tolerate caffeine well. No one should start drinking four cups a day solely for SHBG, but if you already enjoy coffee, you might be getting a modest SHBG boost as a side benefit.

Vitamin D

Vitamin D status and SHBG tend to track together. In a study of Malaysian men, vitamin D levels were positively associated with SHBG even after adjusting for age, ethnicity, and BMI, and SHBG values climbed in a stepwise fashion from vitamin D-deficient to vitamin D-sufficient individuals.¹⁹ A larger multi-ethnic study in the United States found similar results: in women, every 10 ng/ml decrease in vitamin D corresponded to an average drop of about 8 nmol/l in SHBG. In men, the same vitamin D decrease corresponded to a smaller but still statistically significant drop in SHBG.²⁰

These are observational findings, so it is hard to say whether correcting a vitamin D deficiency will directly raise SHBG or whether both are simply markers of overall metabolic health. Still, given that vitamin D deficiency is common and correctable, and that the association with SHBG is robust across populations, it is worth making sure you are not running low. Sunlight, fatty fish, and supplementation during winter months are the standard options.

Thyroid Function

Your thyroid hormones have a surprisingly direct effect on SHBG. Hyperthyroidism drives SHBG up, and hypothyroidism drives it down. In clinical studies, treating hypothyroid patients with thyroid hormone replacement led to significant increases in SHBG.²¹ The mechanism works through the same HNF-4α switch that sugar and fat use: thyroid hormones boost HNF-4α expression in the liver and also reduce the liver’s stores of palmitate (a fatty acid), both of which push SHBG production upward.²²

This has practical implications. If your SHBG is persistently low and you have symptoms of underactive thyroid (fatigue, weight gain, cold sensitivity, sluggish metabolism), it is worth having your thyroid checked. SHBG levels have been used clinically as a peripheral marker of thyroid status; it is one of the hepatic proteins that shifts reliably with thyroid hormone levels.²³ Treating the underlying thyroid problem often normalizes SHBG on its own.

Alcohol and SHBG

Heavy alcohol intake drives SHBG upward, not downward, which might seem like a good thing until you consider the context. In non-cirrhotic alcoholic patients, SHBG was markedly elevated during active drinking. When patients achieved abstinence, SHBG slowly declined toward normal over about twelve weeks. Those who relapsed saw SHBG stay high or climb further.²⁴ The elevated SHBG in heavy drinkers likely reflects liver stress rather than improved metabolic health. It is a useful clinical marker for detecting ongoing alcohol misuse, but it is not the kind of SHBG increase anyone should pursue. The goal is to raise SHBG through a healthier liver, not a damaged one.

Things That Do Not Work as Well as Claimed

Flaxseed is sometimes recommended in online wellness spaces as a way to raise SHBG, particularly for women with PCOS. The evidence does not support this. A meta-analysis of ten randomized controlled trials found that flaxseed supplementation had no significant effect on SHBG (or on most other sex hormones, for that matter).²⁵ An earlier controlled study in premenopausal women found the same: no changes in SHBG with flaxseed or wheat bran.²⁶ Flaxseed has other nutritional virtues, including fiber and omega-3s, but SHBG-raising is not one of them based on current evidence.

Similarly, many supplement companies market herbal formulations as “hormone balancers” that will normalize SHBG. The evidence base for most of these is thin to nonexistent. The interventions that have solid evidence behind them tend to be less glamorous: losing body fat, eating less sugar, managing insulin resistance, and making sure your thyroid and vitamin D levels are in order.

Estrogen and Oral Contraceptives

Estrogen is one of the most potent stimulators of SHBG production, which is why SHBG levels tend to be higher in women than men and why oral contraceptives dramatically increase SHBG. Oral conjugated estrogens caused significant and considerable increases in SHBG in studies of menopausal women, whereas transdermal estrogen had little effect.²⁷ The route of administration matters because oral estrogen passes through the liver first, hitting the SHBG-producing machinery directly. Transdermal estrogen enters the bloodstream without that first pass, leaving SHBG largely unchanged.²⁸

This is relevant for women on hormone replacement therapy or hormonal contraception. Oral contraceptive pills and contraceptive patches both raise SHBG substantially.²⁹ For women with PCOS, in whom SHBG is typically low and free androgens are high, oral contraceptives serve a dual purpose: they suppress ovarian androgen production and boost SHBG, which binds up more of the circulating testosterone. This is part of why combined oral contraceptive pills are a first-line treatment for androgenic symptoms in PCOS. If you stop taking oral contraceptives, your SHBG will typically return to its prior level within a few months.

Genetics Set the Baseline

Not everyone starts from the same place. Variations in the SHBG gene itself influence how much SHBG you produce, independent of your diet, weight, or insulin levels. Certain gene variants are associated with SHBG concentrations that are 10 to 25 percent higher or lower than average. For example, one common variant (rs6258) was associated with about a 25 percent lower SHBG, while several others (rs6259, rs727428, rs1799941) were linked to SHBG that was 11 to 23 percent higher.³⁰ Research in women with PCOS found that certain of these same variants influenced SHBG levels independently of BMI and insulin resistance.³¹

What this means practically is that two people with the same diet, same weight, and same insulin sensitivity can still have meaningfully different SHBG levels based purely on their genetic hand. If you have been doing everything right and your SHBG is still on the low side, genetics might be a contributing factor. That does not mean lifestyle changes are pointless; they still shift your SHBG relative to your own baseline. It just means comparing your numbers to someone else’s can be misleading. Your target should be moving your own SHBG in the right direction rather than hitting a specific number.

Putting the Levers Together

The interventions with the best evidence fall into a handful of categories, roughly ordered by how much they move the needle:

• Lose excess body fat: This is the strongest lifestyle lever, working primarily by reducing insulin levels. Even moderate weight loss produces a measurable SHBG increase.
• Reduce sugar and refined carbohydrate intake: Simple sugars suppress SHBG production directly in the liver through fat accumulation that lowers the key transcription factor HNF-4α.
• Check thyroid function: Untreated hypothyroidism is a correctable cause of low SHBG that no amount of dietary optimization will overcome.
• Maintain adequate vitamin D: The association between vitamin D and SHBG is consistent across multiple populations, and deficiency is easily corrected.
• Moderate dietary fat: Very high-fat diets suppress SHBG, while lower-fat diets support higher levels.
• Coffee: The effect is modest but real in observational studies, and caffeine is the active component.

Most of these strategies converge on the same underlying mechanism: they improve insulin sensitivity and reduce the fat burden on your liver, allowing HNF-4α and SHBG production to ramp up. That convergence is actually reassuring. It means you do not need to chase a dozen separate interventions. If you focus on metabolic health broadly, SHBG tends to follow.

When to Talk to a Doctor

SHBG is not a routine screening test in most clinical settings, but it may be ordered when symptoms suggest a hormonal imbalance, particularly in the context of suspected PCOS, low testosterone evaluation, or metabolic syndrome. If your SHBG is flagged as low, the most important first step is evaluating whether you have untreated insulin resistance, thyroid dysfunction, or another underlying condition driving it down. Lifestyle changes are powerful, but they work best when you are not fighting against an undiagnosed medical problem. A clinician can help distinguish between SHBG that is low because of modifiable habits and SHBG that is low because of something that needs specific treatment.