Do seed oils actually lower testosterone? We checked

What did @onehottrail actually say?

The short version: he deliberately overconsumed seed oils during a dirty bulk, gained roughly 25 pounds, and watched his total testosterone drop from an unstated baseline to 937 ng/dL. His conclusion was measured: "chronic overconsumption of any foods can lead to negative outcomes" but typical seed oil intake probably won't hurt a healthy adult. That's a more responsible takeaway than most testosterone content on this platform delivers.

He tracked linoleic acid intake, liver enzymes, hemoglobin A1C, insulin, lipids, estradiol, LH, FSH, SHBG, and both total and free testosterone. That's a genuinely thorough panel. He also acknowledged confounders: reduced training frequency, significant fat gain, and a worsening omega-3 to omega-6 ratio. The self-awareness here is above average for Instagram health content, even if the experiment design has serious problems.

Does the science back this up?

Partially, but the causal arrow is almost certainly pointing at body fat, not seed oils specifically. The data on linoleic acid and testosterone in humans is weak and inconsistent. The data on obesity suppressing testosterone is robust.

A 2021 meta-analysis by Hu et al. in Obesity Reviews confirmed that increased adiposity reliably elevates aromatase activity, converting testosterone to estradiol, which suppresses LH via negative feedback. His estradiol rising from 35 to 41 pg/mL and total testosterone falling are textbook consequences of going from roughly 10-12% to 20% body fat, regardless of what cooking oil he used.

On linoleic acid specifically: a 2021 review by Hamley in Prostaglandins, Leukotrienes and Essential Fatty Acids found no consistent evidence that dietary omega-6 intake suppresses testosterone in humans at realistic intake levels. Rodent studies showing linoleic acid effects on Leydig cell function exist, but rodent lipid metabolism differs enough from human physiology that extrapolating directly is a stretch most endocrinologists won't make.

What did they get wrong (or right)?

Credit where it's due: his final conclusion is basically correct. The wrong part is the framing of the experiment itself, which implies seed oils were the active variable when body fat gain almost certainly did the heavy lifting.

Going from 165 to 190 pounds while "nearing obesity BMI" and pushing 20% body fat is not a controlled seed oil intervention. It's a weight gain study with seed oil consumption as one uncontrolled dietary component among many. Calories increased substantially, processed food intake likely increased, sleep quality may have changed with weight gain, and training dropped to 2-3 sessions per week. Any one of those variables could explain his testosterone drop independently.

His lipid panel changes, specifically rising LDL and triglycerides, are also more consistent with caloric surplus and saturated fat co-consumption during a dirty bulk than with linoleic acid specifically. Linoleic acid in controlled trials tends to lower LDL, not raise it, per Mozaffarian et al., 2010, PLOS Medicine.

The interpretation of his LH increasing as a positive sign also deserves scrutiny. Elevated LH alongside falling testosterone can indicate primary testicular insufficiency or, more likely here, a compensatory response to suppressed free testosterone. It is not necessarily reassuring.

What should you actually know?

Seed oils are not the testosterone villain that corners of the internet insist they are. The anti-seed oil narrative has outrun the evidence considerably. That doesn't mean unlimited processed food consumption is fine, but the specific mechanism, linoleic acid directly suppressing Leydig cell function at normal dietary intakes, has not been established in controlled human trials.

What does reliably suppress testosterone is excess body fat. If someone gains 25 pounds of fat while eating anything, seed oils, butter, olive oil, or lard, they should expect their testosterone to trend downward and their estradiol to trend upward. The endocrinology here is well established. Adipose tissue expresses aromatase. More fat means more conversion of androgens to estrogens.

If you're concerned about your testosterone levels, the most evidence-backed lifestyle interventions remain resistance training, adequate sleep, maintaining a healthy body weight, and limiting chronic alcohol use. A clinician, not a self-experiment with uncontrolled variables, is the appropriate starting point for evaluating hypogonadism symptoms.

Bottom line: is this video worth your time?

More so than most testosterone content in this category. The creator ran real labs, acknowledged confounders, and landed on a reasonable conclusion. But the experiment cannot tell us what he implies it might tell us, because body fat gain and seed oil overconsumption were completely entangled. Treat it as an entertaining n-of-1 diary with a sensible moral, not as evidence about seed oils and testosterone.