What did @cesar_contrerasjr actually say?
Cesar claims he raised his testosterone from 170 ng/dL to over 500 ng/dL without TRT, injections, or topical hormones. He attributes this entirely to reversing insulin resistance through four lifestyle changes: intermittent fasting, reducing carbohydrates, lifting weights, and adding dietary fiber. He also references a randomized controlled trial on low-carbohydrate diets improving testosterone and erectile function in men with metabolic syndrome. Along the way, he says he reversed sleep apnea and got off antidepressants. That is a lot of claims packed into one video.
To his credit, he does not sell a product. He does not recommend a specific supplement stack. And he anchors his argument in a real mechanism: that hyperinsulinemia suppresses sex hormone-binding globulin (SHBG) and, by extension, free testosterone. That is not fringe science. But the gap between the mechanism and his personal result deserves scrutiny.
Does the science back this up?
The core mechanism is real, but the magnitude of his result is an outlier, not a typical expectation. Hyperinsulinemia does suppress SHBG, which lowers total and free testosterone. Studies confirm this relationship is bidirectional and clinically meaningful.
The randomized controlled trial he references is likely the work of Khoo et al. (2011, Asian Journal of Andrology) or more recent work by Bianchi et al. (2023, Nutrients), which found that low-carbohydrate dietary interventions improved testosterone levels and sexual function markers in obese men with metabolic syndrome. These are real findings. However, baseline testosterone in those studies typically ranged from 200 to 350 ng/dL, and improvements averaged 100 to 200 ng/dL, not the 330-point jump Cesar reports.
A 2020 meta-analysis by Grossmann and Matsumoto in the Journal of Clinical Endocrinology and Metabolism confirmed that weight loss and insulin sensitization can meaningfully raise testosterone, particularly in men who are obese or have type 2 diabetes. But men with primary hypogonadism, where the testes themselves are underperforming regardless of insulin status, are unlikely to see the same response. Cesar never rules out that his original 170 reading was situationally suppressed, possibly by poor sleep, acute illness, or the timing of the draw.
What did they get wrong (or right)?
He got the mechanism right. Insulin resistance lowers SHBG, SHBG lowering reduces total testosterone, and fixing insulin resistance can reverse that. The four interventions he lists, fasting, carb reduction, resistance training, and fiber, are all independently supported by evidence for improving insulin sensitivity.
What he likely got wrong, or at least incomplete: a single testosterone reading of 170 ng/dL is not a diagnosis. The Endocrine Society recommends at least two morning fasting measurements before acting on a low result. A lab draw at the wrong time of day, after poor sleep, or during illness can produce artificially suppressed numbers. If his baseline was situationally low, part of his apparent gain might reflect normalization rather than a physiological transformation.
He also implies this approach works universally, saying "if you can manage your insulin, your testosterone will go up." That overstates it. Men with primary hypogonadism, Klinefelter syndrome, or pituitary dysfunction will not recover testosterone through lifestyle alone. His result is plausible but not generalizable to everyone watching with low T.
His claim that he "reversed sleep apnea" is worth flagging. Weight loss does reduce sleep apnea severity, and that is documented. But calling it a reversal without a follow-up sleep study is an unverifiable personal claim, not a medical conclusion.
What should you actually know?
Insulin resistance is an underappreciated driver of low testosterone in men who are overweight or have metabolic syndrome, and it is genuinely under-discussed in standard care. If your low testosterone comes with a high fasting insulin, elevated triglycerides, or abdominal obesity, lifestyle intervention is a reasonable and evidence-backed first step before jumping to TRT.
That said, lifestyle alone will not rescue everyone. Men with persistently low testosterone after optimizing metabolic health, particularly those with levels below 300 ng/dL alongside symptoms, should have a full workup: LH, FSH, prolactin, and a second morning draw. The question is not whether lifestyle helps. It often does. The question is whether it is sufficient for your specific cause of low testosterone.
Resistance training deserves a specific mention. A 2021 review by Vingren et al. in Sports Medicine confirmed that acute resistance exercise transiently raises testosterone, and consistent training over months contributes to improved baseline levels, particularly in sedentary or overweight men. This is not placebo. It is a real effect, and it works partly through improved insulin sensitivity and partly through direct neuroendocrine signaling.
If you are sitting at 170 ng/dL and symptomatic, do not self-diagnose and do not treat based on a TikTok video, including this one. Get a proper workup. But also do not dismiss the role of metabolic health in your hormone picture. Both things can be true.