Low estrogen in men leads to a surprisingly wide range of problems, from weaker bones and increased body fat to reduced sex drive and a higher risk of heart disease. Most people associate estrogen with women, but men produce it too, and their bodies depend on it. The typical reference range for estradiol (the primary form of estrogen) in men is 10 to 40 pg/mL, with healthy young men averaging around 29 pg/mL. When levels drop below that range, the effects show up across nearly every major system in the body.
How Men Produce Estrogen
Men don’t produce estrogen the same way women do. Instead, an enzyme called aromatase converts testosterone into estradiol. This conversion happens throughout the body, particularly in fat tissue, bone, and the brain. So estrogen in men is essentially a downstream product of testosterone, and anything that disrupts either testosterone production or aromatase activity can push estradiol levels down.
The most common reasons men end up with low estrogen include low testosterone itself (since there’s less raw material for conversion), certain medications that block aromatase, and, rarely, a genetic condition called aromatase deficiency where the enzyme barely functions at all. Men on aromatase inhibitors, sometimes prescribed to manage high estrogen or used during testosterone therapy, can accidentally drive their estradiol too low and trigger the symptoms described below.
Sexual Function and Libido
Testosterone gets most of the credit for male sex drive, but estrogen plays a necessary supporting role. In men with testosterone levels below 300 ng/dL, sexual desire was markedly higher when their estradiol levels were above 5 ng/dL compared to when estradiol was lower. When men with low testosterone were given a potent aromatase inhibitor to eliminate estradiol, their libido dropped further, confirming that stripping away estrogen makes things worse even when testosterone is already low.
One particularly telling case involved a man with both aromatase deficiency and low testosterone. Neither estrogen nor testosterone alone was enough to restore his sex drive. He needed both. This suggests estrogen isn’t just a minor player; it’s a required ingredient for normal sexual desire in men, at least when testosterone is on the lower end. Erectile function also suffers. Low testosterone impairs erection quality, firmness, and frequency, and abnormal estrogen levels (whether too high or too low) add to the problem independently.
Bone Loss and Fracture Risk
Estrogen is one of the primary regulators of bone turnover in men. It slows down the cells that break bone apart while supporting the cells that build it back up. Testosterone contributes too, mainly by stimulating the outer shell of bones to grow thicker, but estrogen is responsible for maintaining the internal spongy bone (trabecular bone) that gives bones their structural integrity.
As men age and estradiol levels decline, bone mineral density drops in a pattern that correlates directly with falling estrogen. Over time, this can progress to osteoporosis, a condition where bones become fragile enough that a minor fall causes a fracture. Men generally start with denser bones than women and lose bone more slowly, but estrogen deficiency accelerates that loss. In men with congenital aromatase deficiency, severely compromised bone health is one of the earliest and most consistent findings.
Fat Gain and Metabolic Problems
One of the more striking effects of low estrogen in men is rapid fat accumulation, particularly around the midsection. Research from clinical intervention studies suggests estradiol may actually be a stronger driver of body fat levels than testosterone in men. When men were made temporarily sex-steroid deficient in controlled studies, significant increases in body fat appeared within just four weeks. And it was estradiol deprivation, more than testosterone deprivation, that correlated most strongly with the fat gain.
Testosterone, by contrast, appeared to be the main hormone governing lean muscle mass. So the two hormones divide labor: testosterone protects muscle, estrogen protects against fat. Lose estrogen, and the metabolic consequences go beyond cosmetic weight gain. Men with congenital estrogen deficiency develop a recognizable metabolic pattern that includes increased central (visceral) fat, insulin resistance, and fatty liver disease. Animal studies back this up: male mice lacking functional estrogen receptors accumulated more than double the body fat of normal mice as they aged.
Mood, Energy, and Cognitive Function
Estradiol acts directly on brain regions involved in mood regulation, including the hippocampus and the amygdala. Men with hypogonadism (low sex hormones overall, which typically means low estrogen as well) show higher rates of depression, fatigue, confusion, and general inactivity compared to healthy controls. Young men with congenital hormone deficiency report reduced vitality, difficulty with emotional functioning, and significantly more depressive symptoms on standardized screening tools.
Cognitive function takes a hit too. Men in hormone-deficient states show measurable impairments in certain cognitive domains, along with reduced quality of life in social and psychological areas. That said, the mood effects of low estrogen are difficult to fully separate from the effects of low testosterone, since the two usually drop together. One study found that a short course of estradiol treatment alone didn’t improve depressed mood in older men on androgen deprivation therapy, suggesting testosterone may need to be present as well for mood benefits to materialize.
Heart Disease Risk
Low estradiol levels are associated with a meaningfully higher risk of dying from cardiovascular disease. A large U.S. study using nationally representative data found that after controlling for standard heart disease risk factors and testosterone levels, each standard-deviation drop in estradiol was linked to a 2.3 times higher risk of cardiovascular death in young and middle-aged men. The association held for free estradiol as well, with a 1.9 times higher risk per standard-deviation decrease. This connection was strongest in non-Hispanic White men in the study population.
The mechanisms likely involve estrogen’s protective effects on blood vessels and lipid metabolism, though the research is still filling in the details. What’s clear is that very low estradiol isn’t metabolically neutral for men’s hearts.
Connective Tissue and Muscle
Beyond bone, estrogen supports other structural tissues in the body. It increases the collagen content of connective tissues like tendons and ligaments, and it contributes to muscle mass and strength. Men with chronically low estrogen may notice joint stiffness or discomfort, and their recovery from musculoskeletal injuries could be slower due to reduced collagen production.
Getting an Accurate Measurement
If you suspect low estrogen, the type of blood test matters. Standard immunoassay tests, the kind most labs default to, were designed to measure the higher estrogen levels found in women. At the lower concentrations typical of men, these tests lose accuracy and can cross-react with similar molecules, giving unreliable results. A more advanced method called LC-MS/MS (sometimes marketed as a “sensitive estradiol” test) measures much lower levels precisely and can distinguish estradiol from structurally similar compounds. If your results seem inconsistent with your symptoms, asking for the sensitive assay version is worth it.
What Treatment Looks Like
There are no widely adopted standalone estrogen replacement guidelines for men the way there are for women. In most cases, the practical fix is addressing the upstream cause. If low estrogen stems from low testosterone, testosterone replacement therapy raises both hormones, since aromatase will convert some of the supplemented testosterone into estradiol naturally. For men already on testosterone therapy who are also taking an aromatase inhibitor, the solution may be as simple as reducing or stopping that medication to let estradiol recover.
In rare cases like congenital aromatase deficiency, direct estradiol supplementation has been used, but this remains an uncommon clinical scenario. The key takeaway is that estrogen in men isn’t something to suppress aggressively. Driving it too low, whether through medication or underlying disease, creates a distinct set of health problems that mirrors many of the symptoms men associate with low testosterone alone.