@aleksfidurski's keto and TRT claims need some context

What did @aleksfidurski actually say?

The claim here is that keto diets are counterproductive for testosterone. @aleksfidurski argues that low-carb eating raises cortisol, suppresses testosterone, and tanks thyroid function. The fix, according to the video, is to eat carbs, specifically fruit, honey, and orange juice, to keep your metabolism high and testosterone elevated.

That's a tidy narrative. Some of it has real science behind it. Some of it oversimplifies things enough to mislead men who are already confused about what diet actually does to their hormones. The devil is in the details, and this video skips several of them.

Does the science back this up?

Partially. The cortisol connection is real, but incomplete. And the testosterone story is more complicated than "carbs good, keto bad."

On cortisol: there is evidence that very low carbohydrate diets can transiently increase cortisol. A study by Stimson et al. (2007, Journal of Clinical Endocrinology and Metabolism) found that low-carb diets altered cortisol metabolism, though the clinical significance for testosterone suppression in healthy men remains debated.

On thyroid: keto does tend to lower T3 levels, the active thyroid hormone. This is documented. Phinney et al. and others have noted this effect. Whether that "tanks your metabolism" in a way that meaningfully suppresses testosterone in otherwise healthy men is a stretch. Adapted ketogenic dieters often maintain metabolic rate better than the video implies.

On testosterone itself: the picture is genuinely mixed. Some research shows lower-fat diets reduce testosterone. Hamalainen et al. (1984, Hormone and Metabolic Research) found that low-fat, high-fiber diets decreased serum testosterone in men. That directly contradicts the video's conclusion that carbs are the lever to pull.

What did they get wrong (or right)?

They got the cortisol mechanism directionally right, but overclaimed it. Saying studies show low-carb diets raise cortisol in a way that "suppresses testosterone" is a leap. The acute cortisol response does not automatically translate to chronic testosterone suppression in every man.

They got the thyroid point partly right. Keto does lower T3. But framing this as your metabolism being "tanked" overstates the effect for most people, and ignores that metabolic adaptation on keto is a well-studied phenomenon, not simply a shutdown.

The biggest problem is the conclusion: "if you want high testosterone, you need carbs." That is not supported by the literature as a universal statement. Dietary fat intake is actually one of the stronger dietary predictors of testosterone. Men eating very low fat diets, regardless of carb content, tend to show lower testosterone. The video ignores this entirely.

Recommending orange juice and honey as testosterone-supporting foods is not evidence-based. It is influencer nutrition dressed up as physiology.

What should you actually know?

Testosterone is sensitive to overall caloric intake, body fat percentage, sleep, and dietary fat, not just carbohydrate content. If you are eating enough calories, enough dietary fat, and maintaining a healthy body composition, the macronutrient split matters far less than this video suggests.

For men with clinically low testosterone, no dietary change, keto or otherwise, replaces proper evaluation and treatment. If you are symptomatic, low energy, low libido, poor body composition, get your levels tested. Diet optimization is useful, but it is not a substitute for clinical assessment.

The research on keto and testosterone is genuinely inconsistent. Whittaker and Harris (2022, Nutrition and Health) reviewed dietary fat and testosterone and found that higher fat intake supported testosterone, but carbohydrate restriction effects were context-dependent. That kind of nuance does not fit into a 45-second TikTok, which is exactly why you should be cautious about optimizing your hormones based on one.