HoldsUp

Mark Hyman, MD · 2025-08-27 · Mark Hyman (host), Ben Greenfield

Why I Stopped 'Biohacking' and Started Living | Ben Greenfield

36 research-tied claims examined: 4 contradicted 5 overstated 5 context 18 supported 4 unverified

5

Overstated

0:13:26Ben Greenfieldoverstatedmoderate

Super-slow strength training with high time-under-tension (up to about 2 minutes) produces significant strength and cardiovascular adaptations with low training volume and lower injury risk.

"Doug McGuff, I think he was an emergency room physician. He wrote a great book called Body by Science where he gets into the fact that when you move muscles very slowly, very high amounts of what is called time under tension, up to about 2 minutes or so, that you can get really great strength and cardiovascular results with a very low amount of training volume and a low risk of injury" (said at 0:13:26)

While slow-cadence resistance exercise (such as the protocol popularized by Doug McGuff in 'Body by Science') can induce muscle strength gains in untrained individuals, the claims regarding superior or 'great' cardiovascular adaptations and hypertrophy are overstated. Controlled trials comparing super-slow resistance training to traditional resistance training have demonstrated that super-slow protocols elicit lower cardiovascular and metabolic responses (such as lower oxygen uptake and lower heart rates). Furthermore, systematic reviews and meta-analyses show that repetition durations between 0.5 and 8 seconds produce comparable strength and hypertrophic adaptations, while intentionally very slow repetitions (>10 seconds per repetition) may result in inferior muscle stimulus.

0:36:21Mark Hyman (host)overstatedlow

Hyperbaric oxygen therapy activates stem cells, increases stem cell production, clears senescent cells, and increases telomere length.

"The pressure drives more oxygen into tissue. So, it's a way of oxygenating yourself. But what we're finding is that it actually has a lot of benefits in activating stem cells and increasing stem cell production, killing all the zombie cells, which are the senescent aging cells that cause inflammation throughout your body. They increase telomere length." (said at 0:36:21)

Preliminary clinical studies show changes in these biomarkers following specific hyperbaric oxygen therapy (HBOT) protocols, but the claim generalizes and exaggerates the findings (e.g., asserting it 'kills all the zombie cells'). A controlled trial demonstrated that HBOT mobilizes CD34+ stem and progenitor cells from bone marrow into peripheral circulation. Furthermore, a prospective trial in 35 healthy older adults receiving 60 daily HBOT sessions reported a >20% increase in telomere length in isolated peripheral blood mononuclear cells and significant reductions in senescent T cell subsets (such as a 37% decrease in senescent T-helper cells). However, these findings are from small cohorts evaluating surrogate markers in specific blood cell types and skin tissue, rather than full-body elimination of senescence or proven systemic anti-aging outcomes.

0:41:19Ben Greenfieldoverstatedlow

Physical touch activates skin mechanoreceptors such as Pacinian corpuscles to stimulate the vagus nerve, reducing heart rate, blood pressure, and cortisol levels.

"if like I were to shake your hand, we're triggering skin receptors, you know, your Pacinian corpuscles, so you're getting uh you're getting a stimulation of the vagus nerve, which is going to lower blood pressure and lower heart rate and lower cortisol and all those things that we look for when we're trying to increase heart rate variability." (said at 0:41:19)

Tactile stimulation and moderate-pressure touch (such as massage therapy) have been proposed to stimulate subcutaneous pressure mechanoreceptors (such as Pacinian corpuscles), leading to increased vagal nerve activity and downstream reductions in cortisol and blood pressure. However, attributing significant autonomic and endocrine reductions—such as lowering heart rate, blood pressure, and cortisol—to a brief, transient contact like a handshake overstates the magnitude of effect documented in clinical touch and massage research, where prolonged or moderate-pressure stimulation is typically studied.

1:15:31Ben Greenfieldoverstatedmoderate

Unless plant-based foods like legumes and grains are soaked, sprouted, or fermented, amino acid bioavailability is reduced and they can cause gut irritation.

"The issue on that side is unless you're taking the time to properly prepare, you know, soak, sprout, ferment, slow prepare those foods, it's going to do a number on your gut and you're not going to unlock a lot of amino acids from those protein sources anyways." (said at 1:15:31)

The speaker overstates the necessity of specialized preparation methods (soaking, sprouting, or fermenting) for obtaining bioavailable amino acids and avoiding gut irritation. Raw legumes and grains do contain antinutritional factors (such as lectins, protease inhibitors, tannins, and phytates) that can inhibit digestive enzymes, decrease amino acid absorption, and cause gastrointestinal distress. However, standard thermal cooking methods (such as boiling, canning, and pressure cooking) are already effective at inactivating heat-sensitive antinutrients like lectins and trypsin inhibitors, allowing substantial amino acid bioavailability. While sprouting, soaking, and fermentation can further reduce heat-stable antinutrients (like phytate) and enhance in vitro protein digestibility, they are not strictly required for standard cooked legumes and grains to be digestible and safe.

1:09:53Ben Greenfieldoverstatedlow

Prolonged intermittent fasting, such as 16-hour fasts, in premenopausal women causes hormonal imbalances and downregulates fertility.

"especially like premenopausal women who are doing like 16-hour fasts and they're seeing, you know, these intense hormonal imbalances and downregulation of fertility" (said at 1:09:53)

Human evidence on time-restricted eating (TRE) and intermittent fasting in premenopausal females does not show that 16-hour fasts cause intense hormonal imbalances or downregulate fertility. Reviews and clinical studies show that time-restricted eating (e.g., 8-hour eating window / 16-hour fast) generally leaves gonadotropins (LH, FSH), estrogens, progesterone, total testosterone, and SHBG largely unchanged or leads to mild reductions in androgen markers. In women with polycystic ovary syndrome (PCOS), time-restricted feeding actually improves hyperandrogenism, metabolic markers, and menstrual regularity, thereby potentially enhancing fertility rather than downregulating it.

Unverified means no publication matching the claim was located; it does not prove the claim false. Spotted an error? See the corrections policy - disputes from the people quoted are prioritized.