Book review: “Boundless - upgrade your brain, optimize your body & defy aging” by Ben Greenfeld

What is Boundless and who is it for?

Boundless stands out as an encyclopedic guide for human optimization. It does not focus solely on diet, exercise, or any single aspect of health; rather, it integrates cutting-edge science with time-tested practices across mind, body, and spirit. This holistic system is aimed at individuals who have already explored basic wellness advice but seek a cohesive framework to integrate disparate health strategies.

Greenfield’s ideal reader is someone like “Kevin,” a health enthusiast who has experimented with various diets and fitness routines but still feels there is untapped potential for improvement. The book particularly benefits readers interested in:

• Understanding the connections between bodily systems
• Implementing science-backed biohacking techniques
• Enhancing both cognitive and physical performance
• Exploring longevity and anti-aging strategies
• Integrating spiritual and mindfulness practices into health routines

Author background: Ben Greenfield’s biohacking philosophy

Ben Greenfield has established himself as a preeminent voice in the biohacking community, blending scientific research with practical applications. As a New York Times bestselling author with 18 books to his name, Greenfield brings substantial credibility to his work. His professional journey began not in medicine but in exercise physiology and biomechanics, where he earned a Master’s degree after turning down acceptance to six medical schools.

What distinguishes Greenfield from other biohackers is his balanced approach, often described as having “one foot in ancestral wisdom and one foot in modern science.” This philosophy permeates throughout Boundless, where ancient practices like earthing and grounding complement modern technologies and supplement protocols.

Notably, Greenfield prioritizes his life in a specific order: God first, followed by family, health, community, and lastly, business. This hierarchy shapes his approach to optimization—not merely for personal achievement but to better serve others through enhanced physical and mental capabilities.

Book format

Boundless is structured as a three-part guide that systematically addresses mind, body, and spirit optimization. The first section focuses on brain enhancement, covering topics from neurotransmitter balancing to sleep optimization. The middle portion delves into physical performance, addressing muscle building, fat loss, and digestive health. The final third explores longevity, anti-aging protocols, and spiritual practices for fulfillment.

Throughout the book, Greenfield has created extensive resource webpages for each chapter, offering additional content including podcasts, videos, articles, and biohacking techniques. This supplementary material allows readers to explore topics in greater depth beyond the book’s pages.

Rather than reading cover-to-cover, Greenfield designed Boundless as a reference guide, a “last book you’ll ever need” for human optimization. Readers can target specific sections based on their personal health goals or challenges, making this comprehensive work more accessible despite its substantial size.

Brain optimization approaches

According to Boundless, owning an optimized mind means having balanced neurotransmitters, an inflammation-free brain, and effective stress-management strategies. The book outlines several key brain enhancement areas that promise immediate impact on cognitive performance.

Nootropics and smart drugs

Greenfield explains that nootropic substances can provide sustained focus without damaging health. A basic stack recommended in the book includes:

• L-theanine (200mg) paired with morning coffee to elongate caffeine effects and boost alpha brain waves
• Bacopa monnieri (300mg) daily for memory enhancement and processing speed
• Magnesium threonate (200mg) to support overall cognitive function
• CDP-choline for memory support and mental energy

The effects of these supplements typically aren’t immediate but become noticeable after about two weeks. Users often report experiencing 4-5 hours of sustained focus compared to the usual 2-3 hours before needing a break. Additionally, Greenfield’s advice about taking nootropics with healthy fats can significantly improve absorption and effectiveness.

Sleep protocols

Sleep emerges as perhaps the most powerful brain hack in the book. Greenfield’s protocols include several key changes to the sleep environment. First, he recommends installing red incandescent bulbs in bedrooms and bathrooms while using f.lux on devices to automatically filter blue light in the evenings. Despite some research showing mixed effects, many users report falling asleep approximately 20 minutes faster on nights when blue light is strictly avoided.

Temperature control is another key factor, with recommendations to keep bedrooms at 65-67 degrees. This single change can noticeably improve deep sleep according to tracking devices. Consequently, many users report waking feeling more refreshed even when sleeping fewer total hours.

The pre-bed hot-cold shower technique (alternating 20 seconds cold, 10 seconds hot for 10 cycles) initially seems extreme, but after adaptation, it consistently reduces sleep latency and improves sleep quality metrics for many practitioners.

Neurotransmitter balancing

Beyond supplements and sleep, Greenfield emphasizes how specific amino acids serve as building blocks for key neurotransmitters that regulate mood and cognition. His recommendations focus on:

• Tryptophan intake through diet to support serotonin production, which Greenfield notes impacts mood, sleep quality, and even pain sensitivity. Intentionally increasing tryptophan-rich foods often leads to more stable energy throughout the day without afternoon crashes.
• Tyrosine supplementation (500mg) before mentally demanding tasks can be especially effective during stressful work periods. Research supports this approach, showing tyrosine helps maintain cognitive performance during psychological stress.

These amino acid protocols often result in more consistent mood and reduced mental fatigue. The connection between amino acids and neurotransmitter function becomes evident through practical applications of Greenfield’s recommendations.

Body optimization techniques

The physical optimization section of Boundless offers specific protocols that can yield measurable improvements in body composition and performance when implemented correctly.

Fat loss tools

Greenfield’s approach to fat loss focuses on leveraging physiological responses rather than calorie counting alone. Cold exposure emerges as surprisingly effective, yet most people implement it incorrectly. Instead of fighting against shivering (which many protocols recommend), Greenfield explains that shivering is actually the mechanism that triggers fat burning through succinate release and brown fat activation.

A recommended protocol follows this pattern:

• Take cold showers 3 times weekly (water cold enough to trigger genuine shivering)
• Once shivering starts (about 1 minute), exit for 1-3 minutes without drying off
• Re-enter cold water for another 1-3 minutes, repeating 3 cycles total

Beyond cold exposure, Greenfield recommends strategic fasting with morning workouts. For moderate intensity exercise, he describes a “switchover point” phenomenon, where at around 90 minutes of fasted exercise, fat burning increases dramatically. For high-intensity sessions, this effect occurs earlier, making shorter fasted workouts more time-efficient.

Additionally, yerba mate tea before exercise can boost fat oxidation through increased GLP-1 activation, providing a noticeable energy difference compared to regular caffeine.

Muscle building

Greenfield advocates a minimalist approach to resistance training. The key insight is quality over quantity, focusing on perfect execution of fewer exercises with minimal rest between sets.

A twice-weekly full-body routine emphasizing compound movements with strategic modifications is recommended:

• Dumbbell press rather than barbell (greater range of motion and time efficiency)
• Two-grip lat pulldowns to target different muscle angles
• Single working sets taken to near failure for secondary exercises

After six weeks, this minimalist protocol can produce comparable strength gains to traditional 4-day splits while saving nearly 3 hours weekly. Moreover, recovery dramatically improves when combining these workouts with targeted recovery equipment.

Among the recovery tools mentioned in Boundless, percussion massage devices (like TheraGun) [12] are particularly effective for reducing DOMS (Delayed Onset Muscle Soreness) after intense training sessions. Investment in quality recovery gear proves worthwhile as training consistency improves over time.

Gut health

The gut protocols in Boundless can produce cascading benefits throughout the body. Greenfield recommends supplementing with a multi-strain probiotic containing Lactobacillus acidophilus, Bifidobacterium longum, and Saccharomyces boulardii, which can significantly reduce post-meal bloating within two weeks.

A particularly effective approach combines probiotics with digestive enzymes. While probiotics maintain microbial harmony in the lower GI tract, enzymes handle mechanical digestion in the upper GI tract. This synergistic approach provides comprehensive gut support that addresses issues from multiple angles.

For optimal results, Greenfield suggests enzyme supplements containing:

• Amylase, protease, and lipase for breaking down carbohydrates, proteins, and fats
• Specialized enzymes like lactase for dairy digestion
• Bromelain and papain for anti-inflammatory properties

These gut interventions often yield unexpected benefits beyond digestion, including improved energy levels and reduced post-meal brain fog, highlighting Greenfield’s emphasis on the gut-brain connection.

Longevity and anti-aging protocols

Greenfield’s longevity section in Boundless presents anti-aging not just as looking younger but as a systematic approach to cellular regeneration. The book prioritizes several key protocols that can deliver noticeable improvements.

Hormone optimization

Greenfield focuses primarily on natural testosterone support rather than replacement therapy. Research indicates that testosterone therapy can improve erectile function and libido in men with low levels, with studies showing symptomatic improvements in sexual desire. His recommendations include:

• Zinc-rich foods (oysters, pumpkin seeds)
• Vitamin D optimization through morning sun exposure
• Strength training focused on compound movements
• Improved sleep quality through earlier protocols

By day 30 of implementation, many users notice substantially improved morning energy and recovery capacity between workouts. Beyond that, libido often increases noticeably, confirming research that shows improved sexual desire correlates with testosterone support. Essentially, hormone optimization serves as the foundation for other anti-aging benefits.

Skin and beauty hacks

Red light therapy emerges as one of the most surprising discoveries for many readers. This treatment uses low-wavelength red light to penetrate skin at the cellular level, stimulating mitochondria and increasing ATP production. Following Greenfield’s protocol involves using a medical-grade red light panel for 10 minutes daily.

After six weeks, visible improvements in skin texture and elasticity are common. This aligns with research showing red light therapy increases expression of collagen, elastin, and hyaluronic acid in skin. The therapy works by stimulating fibroblasts, which are responsible for producing these proteins.

Interestingly, even at the low-energy levels used in home devices, clinical research confirms red light therapy can induce expression of extracellular matrix proteins in human skin.

Supplements for aging

As noted in Boundless, certain supplements may help address cellular aging directly. Greenfield’s recommended protocol includes:

• NAD+ precursors – Taking nicotinamide riboside (300mg daily) to support NAD+ levels, which naturally decline with age
• Resveratrol – Adding 1000mg daily, which studies suggest can reduce blood glucose levels by up to 35mg/dL
• Curcumin – Supplementing with 1000mg to reduce inflammation markers like hsCRP

Unlike other biohackers spending millions on longevity, Greenfield’s approach focuses on evidence-based interventions with reasonable costs. He advises caution with rapamycin after citing Yale research suggesting it might actually accelerate biological aging across 16 epigenetic markers.

The combined protocols can yield measurable improvements in energy, skin appearance, and recovery speed—demonstrating that strategic anti-aging interventions can produce tangible results even within a relatively short timeframe.

Spiritual and lifestyle shifts

Beyond physical improvements, Boundless explores the often overlooked spiritual dimension of health optimization. These lifestyle shifts can create profound ripple effects across all aspects of wellbeing.

Daily rituals

Greenfield recommends beginning each morning with a 10-minute guided meditation using apps like Calm, which offers over 100 guided sessions covering everything from focus to relationships. This practice yields multiple benefits:

• Improved focus and decision-making
• Enhanced mental resilience during stress
• Increased awareness of unconscious patterns

A 5-minute morning journaling practice is equally valuable in Greenfield’s system. Using a hardcover gratitude journal to answer three simple questions daily: what am I grateful for, what would make today great, and daily affirmations. This ritual noticeably reduces stress levels while increasing overall happiness for many practitioners.

Implementing Wim Hof breathing techniques can provide unexpected energy boosts. After just three weeks, many users experience increased resilience toward everyday stress, improved focus, and faster recovery from workouts.

Environmental detox

In addition to internal practices, Boundless addresses external factors affecting cellular health. Studies indicate electromagnetic fields may lead to cellular fatigue, so Greenfield recommends turning off WiFi at night and keeping phones on airplane mode when not needed.

Indoor air quality presents another challenge, since concentrations of some pollutants can be up to 5 times higher indoors where people spend 90% of their time. Installing HEPA filters and adding plants throughout living spaces can create noticeable improvements in sleep quality.

For water purification, Greenfield recommends specific filtration systems to remove common contaminants while preserving beneficial minerals.

Conclusion: The value of Boundless

Boundless represents a significant contribution to the biohacking literature, distinguished by its comprehensive scope and evidence-based approach. While the sheer volume of information can be overwhelming, the book’s organization as a reference guide makes it accessible for readers at various stages of their health optimization journey.

What sets Boundless apart is Greenfield’s integration of ancestral wisdom with modern science, creating protocols that honor traditional practices while leveraging cutting-edge research. This balanced perspective provides a refreshing alternative to both purely technological biohacking approaches and strictly naturalistic health philosophies.

Ultimately, Boundless delivers on its promise to serve as a comprehensive manual for human optimization, providing readers with the tools to enhance their physical, mental, and spiritual capabilities in an increasingly demanding world.