What did @zack.chug actually say?
He claimed his testosterone dropped, causing what he called "more gyno, low energy, low libido and brain fog." His explanation: chronic stress raises cortisol, which suppresses testosterone, trapping you in a cycle of fatigue and bad habits. His fixes included sleeping more with warm milk and turmeric, taking vitamin D and magnesium, eating dietary fats, and doing heavy compound lifts. Some of this is grounded in real physiology. Some of it is wellness folklore dressed up in endocrinology language.
The cortisol-testosterone connection is legitimate. The warm milk and turmeric sleep hack is a stretch. And attributing gynecomastia to stress alone, without noting other possible causes, is the kind of oversimplification that can send people chasing the wrong problem.
Does the science back this up?
The cortisol-suppression claim holds up reasonably well. Chronic elevation of cortisol does interfere with the hypothalamic-pituitary-gonadal (HPG) axis, which Zack correctly names as central to testosterone production. Cumming et al. (1983, Journal of Clinical Endocrinology and Metabolism) demonstrated that cortisol administration acutely suppressed LH and testosterone in men. More recent work by Whirledge and Cidlowski (2010, Nature Reviews Endocrinology) confirmed that glucocorticoids inhibit GnRH and LH secretion, disrupting the HPG axis.
The claim that sleep "activates your HPG axis producing most of your testosterone" is directionally correct. About 70 percent of daily testosterone release occurs during sleep, particularly in the early hours. Andersen et al. (2011, Sleep) showed that sleep restriction significantly reduced testosterone in young men. The one extra hour prescription is vague but not harmful.
Vitamin D and magnesium have modest supporting evidence. Pilz et al. (2011, Hormone and Metabolic Research) found that vitamin D supplementation raised testosterone in deficient men. Cinar et al. (2011, Biological Trace Element Research) showed similar results for magnesium in athletes. Neither is a guaranteed testosterone booster in men with normal levels.
What did they get wrong (or right)?
The tryptophan-melatonin claim is where things get shaky. Zack says warm milk and turmeric "contains tryptophan which boosts melatonin for deeper sleep." Milk does contain tryptophan, but the amount in a glass is unlikely to meaningfully raise brain serotonin or melatonin on its own. The blood-brain barrier prioritizes tryptophan uptake against competing amino acids, and a protein-containing drink actually works against that process. Wurtman and Wurtman (1995, Scientific American) explained this competition clearly: carbohydrates, not protein, improve tryptophan uptake.
Turmeric has no established role in sleep or melatonin production. That specific claim is unsupported.
The dietary fat claim, that eating avocado, eggs and butter raises cholesterol which builds sex hormones, is technically accurate but oversimplified. Cholesterol is indeed the precursor to steroid hormones. But in men without a severe dietary fat deficiency, adding more saturated fat does not linearly increase testosterone. Hamalainen et al. (1984, Hormone Research) found associations between fat intake and testosterone, but this is not a dose-response relationship most men can exploit by buttering their toast.
Heavy compound lifting raising testosterone is well-supported. Kraemer and Ratamess (2005, Sports Medicine) confirmed that resistance training, especially multi-joint movements at high intensity, acutely and chronically raises testosterone. Credit where it is due.
What should you actually know?
If you genuinely have low testosterone, the symptoms Zack describes, including low energy, low libido, and brain fog, are real and worth taking seriously. But self-diagnosing based on a 60-second Instagram video and then optimizing sleep and eating more butter is not a clinical evaluation. A serum total testosterone test, ideally taken in the morning, is the starting point. Normal range is typically 300 to 1000 ng/dL, and context matters.
Gynecomastia specifically is not reliably caused by cortisol. It can result from elevated estradiol relative to testosterone, certain medications, obesity-related aromatization, or, in some cases, anabolic steroid use. Attributing it to stress without that context is misleading and could delay someone from identifying the actual cause.
The lifestyle interventions Zack recommends, better sleep, resistance training, adequate vitamin D and magnesium, are genuinely supported and low-risk. They are reasonable first steps for men with suboptimal but not clinically low testosterone. They are not a replacement for medical evaluation if symptoms are severe or persistent.
Bottom line
Zack gets the big picture roughly right. Cortisol suppresses testosterone through the HPG axis. Sleep, resistance training, and correcting micronutrient deficiencies are legitimate levers. But the video conflates correlation with mechanism, presents folk remedies like turmeric at bedtime as evidence-based, and glosses over the fact that gynecomastia has multiple possible causes beyond stress. It is a decent starting point for a conversation with a doctor, not a substitute for one.