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Mind Pump · April 20, 2026 · 1h 18m

2840: Breakthrough Muscle Building Peptides with Jay Campbell

Dan Duchaine, Jay Campbell
Show Notes

Jay Campbell returns to discuss cutting-edge peptides for muscle building, including follistatin derivatives and retatrutide, while diving into the history of cyclical ketogenic dieting and why aromatase inhibitors are limiting modern bodybuilding physiques. The episode covers the real protocols that drove 90s mass-building success and the emerging compounds that could reshape lean mass development.

This summary was generated from show notes and public descriptions, not from a full transcript review. Details may contain inaccuracies.

Curious

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Long-Term Ketogenic Dieting Impairs Insulin Metabolism7:52
Chronic ketogenic dieting can degrade insulin sensitivity and raise A1C levels even in the absence of carbohydrate consumption, suggesting the body adapts to long-term zero-carb states in ways that damage metabolic health.
ClaudeChatGPTGemini
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Estrogen Ratio to Testosterone Matters More Than Absolute Levels14:26
For men on testosterone replacement, the ratio of estrogen to testosterone is more metabolically and physiologically significant than the absolute concentration of either hormone.
ClaudeChatGPTGemini

Novel

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Follistatin Derivative FLGR: 19-Day Half-Life Selective Androgen Receptor Modulator18:58
A new follistatin-based peptide (FLGR) has a 19-day half-life and selectively binds only to non-organ-sensitive androgen receptors, potentially enabling muscle growth without side effects common to androgens.
ClaudeChatGPTGemini
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Super Retatrutide: Once-Every-Two-Months Injection Efficacy27:15
A new retatrutide variant may require injection only once every two months while maintaining full fat loss and metabolic effects, dramatically extending the half-life compared to standard GLP-1 agonists.
ClaudeChatGPTGemini

Highlights

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Cyclical Ketogenic Dieting Protocol5:21
Zero carbohydrates Monday through Friday with a depletion workout Saturday morning, followed by unlimited carb loading from Saturday afternoon through Sunday night—a protocol that drove 90s bodybuilding success.
ClaudeChatGPTGemini

Editorial

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High-Dose Insulin + Carb Manipulation Was the Real Secret of 90s Mass1:42
The legendary physiques of 1990s bodybuilders weren't primarily built by steroids alone, but by sophisticated use of high-dose insulin combined with cyclical carbohydrate manipulation to drive anabolic signaling.
ClaudeChatGPTGemini

Contradicts

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Aromatase Inhibitors Block Fat Loss Below 7-8% Body Fat14:26
Aromatase inhibitors, commonly used to control estrogen in bodybuilders on testosterone, paradoxically prevent achieving ultra-low body fat by blocking a critical mechanism of adipose tissue reduction.
ClaudeChatGPTGemini

References

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The Poliquin Principles — Charles Poliquin — Referenced for strength and body composition training principles

Misc

✧Dan Duchaine pioneered the ECA stack (ephedra-caffeine-aspirin) and carb cycling in bodybuilding
✧90s mass monsters used high-dose insulin + carb manipulation, not just steroids
✧Cyclical keto was revolutionary: zero carb Mon-Fri, depletion workout Sat AM, then unlimited carbs through Sunday
✧Jay emphasizes estrogen *ratio* to testosterone matters more than absolute estrogen levels for TRT users
✧Aromatase inhibitors may actually prevent achieving sub-7-8% body fat by blocking a critical fat loss mechanism
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