Episode 387: Nathan T. Jenkins on Metabolic Flexibility, Aerobic Base, and First Principles

Can you really build more muscle just by rethinking how you dose leucine and essential amino acids? Dr. Daniel A. Traylor, Ph.D. — co-founder and principal scientist of LEUVATE™ — reveals the science behind protein quality, muscle protein synthesis, and why older adults may need twice the protein dose to get the same results as younger people. We dig into mTORC1 signaling, sarcopenia, the 30g protein absorption myth, GLP-1 drug effects on muscle, and the clinical trial data behind LEUVATE™. If you care about muscle, longevity, or protein strategy, this one is loaded. Guest Bio Daniel A. Traylor, Ph.D. is an Assistant Professor of Health Sciences at DePaul University in Chicago and Owner, Co-Founder, and Principal Scientist of LEUVATE™. His research explores how protein quality, amino acids, and exercise interact to influence muscle adaptation, recovery, and physical function across the lifespan. He is the co-inventor of LEUVATE™ — a precision-engineered leucine-enriched nutritional formula validated across multiple peer-reviewed human clinical trials. Timestamps 3:36 — Can you really only absorb 30g protein at once? 9:16 — Sarcopenia: the muscle-loss crisis in aging 16:01 — mTORC1 and what triggers muscle protein synthesis 20:46 — Why older adults may need twice the protein dose 30:26 — The origin story of LEUVATE™ 34:01 — Leucine: the master switch for MPS 37:56 — How leucine acts as a dimmer on mTORC1 53:21 — GLP-1 drugs, muscle loss, and amino acid needs 1:06:36 — LEUVATE™ vs whey: MPS data and ongoing trials 1:17:01 — How leucine-enriched EAAs signal differently in the gut 1:27:11 — Protein spiking and supplement quality red flags Resources LEUVATE™ Dr. Traylor email Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this solo episode, Dr. Mike T. Nelson introduces the concept of coaching leverage—the idea that effective coaching means multiplying physiological impact by a client's realistic ability to change. Why sleep is a physiological powerhouse but a coaching nightmare The coaching leverage formula: physiology × psychology Why protein ranks #1 (score: 81) and sleep ranks #8 (score: 20) How to stop majoring in the minors with your clients The eight interventions inside the Flex Diet Certification Why following a proven system beats reinventing the wheel The Flex Diet Certification closes tonight (Monday, June 22, 2026) at midnight Pacific. Get details here. Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this episode of the Flex Diet Podcast, I sit down with Dr. Sara Campbell, Ph.D., Associate Professor at Rutgers University, for a conversation about the bidirectional relationship between exercise and the gut microbiome. Dr. Sara Campbell returns to discuss her lab's cutting-edge research on the bidirectional relationship between exercise and the gut microbiome — including why consumer gut tests oversimplify a complex ecosystem, how antibiotics devastate exercise capacity in animal models, and why single-microbe probiotics miss the bigger picture of functional guilds. She also shares new findings on short-chain fatty acids, amino acid metabolomics after antibiotic treatment, and the emerging neuromuscular junction hypothesis. In this episode you'll learn: Why consumer gut microbiome tests are misleading and what functional guilds tell us instead How antibiotics devastate exercise capacity and the surprising metabolomic changes they cause The current evidence on probiotics for exercise performance and why single strains fall short What short-chain fatty acids do for gut health and exercise, and the emerging neuromuscular junction hypothesis Find Sara here:Rutgers Faculty Page Google Scholar: Sara Chelland Campbell --- The Flex Diet Podcast is brought to you by the Flex Diet Certification. Learn more at miketnelson.com Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this solo episode, Dr. Mike T. Nelson dives into the intersection of AI and coaching. Using his quest to pick up the 175-pound Inch dumbbell as an example, he shows how AI struggles with niche topics where quality training data is scarce — and why that matters for fitness advice. Topics covered: Why AI gave terrible advice on training for the Inch dumbbell — and what that reveals about how AI sources information The protein-and-kidney-damage myth: when AI repeats bad science Where AI actually helps coaches: data analysis, blood work organization, backend tasks, and production workflows Why clients still want (and need) a real human coach — accountability, customization, and skin in the game Will people be compliant to a robot coach? Probably not The baseline is rising: why just writing training and nutrition programs isn't enough anymore Flex Diet Certification — now open through Monday, June 22nd, 2026 at midnight PST. Eight interventions (protein, fats, carbs, exercise, sleep, micronutrition, fasting, and more) built on coaching leverage and metabolic flexibility. Includes direct email access to Dr. Nelson for enrolled students. Enroll now: https://miket.me/fdc Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

Dr. Emily Dow, PhD, RD, is a researcher and registered dietitian working at the intersection of nutrition, resistance training, and gut health. Does vinegar actually do anything for your gut or your blood sugar? Can you trust a $200 mail-in microbiome test? Emily built her dissertation around questions like these, and her honest answers are a lot more useful than the marketing. Expect to learn what a 12-week resistance-training-plus-vinegar protocol did (and didn't do) to gut permeability, why a null result in a healthy population is still worth your attention, what the research really says about vinegar and glucose control, why the peptide boom warrants a hard dose of skepticism, what direct-to-consumer gut testing genuinely can and can't tell you, the underrated role stress plays in GI symptoms, and why the best practitioners do both research and hands-on coaching — and much more. — Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter Connect with Dr. Dow: Website: https://www.dremilydow.com Instagram: https://www.instagram.com/dremilydow Episodes you'll enjoy next: #127 — The Effect of Antibiotics on Muscle Mass & Cardiovascular Performance with Dr. Sara Campbell: https://flex-diet-podcast.simplecast.com/episodes/episode-127-the-effect-of-antibiotics-on-muscle-mass-aerobic-cardiovascular-performance-and-more-an-interview-with-dr-sara-campbell #222 — Nutrition, Supplements & Training with RD Sean Casey https://flex-diet-podcast.simplecast.com/episodes/episode-222-expert-insights-on-nutrition-supplements-and-training-with-registered-dietician-sean-casey Enjoying the show? Follow the Flex Diet Podcast in your podcast app so new episodes land automatically — it's the single best way to help others find it. Timeline  0:00 Intro 02:29 Vinegar Research Origins  04:12 Study Design & Training Protocol 07:42 Biodex Explained: Strength Testing  11:49 Research Tradeoffs & Null Results  14:49 Possible Mechanisms: Acetate  19:55 Glycemic Control & CGM Findings  22:21 Peptides: Hype and Risks  28:54 Microbiome & Performance Research 30:47 Gut Testing Skepticism  36:23 Stress and GI Symptoms  39:22 PhD to RD Fast Track  41:04 RD Exam Reality Check  44:25 Scope of Practice Basics  45:56 Referral Networks That Work  49:29 Research vs. Coaching Gap  58:51 Clients Drive Better Questions  01:05:26 Why She Started Instagram  01:09:58 Social Media for Academia  01:13:18 Training Goals and Tattoos  01:15:45 Where to Follow & Wrap Up   Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this episode of the Flex Diet Podcast, I sit down with Dr. Nathan Jenkins to discuss how to improve performance, body composition, and long-term health through the lens of aerobic development and metabolic flexibility. Nathan shares his journey from exercise physiology and coaching CrossFit athletes to his new role teaching physiology at the University of Georgia School of Medicine. We discuss why metabolic flexibility is such a powerful framework for understanding everything from biochemistry and exercise performance to metabolic disease. We also dive into interpreting maximal exercise testing data, including VO₂ measurements, EKG analysis, and near-infrared spectroscopy (NIRS), along with how different energy systems work together during training and competition. Nathan explains why building an aerobic base is critical for repeated high-intensity performance, how pacing impacts outcomes, and why the ability to "suffer" is actually a trainable skill. To wrap up, we cover practical strategies you can apply right away, including prioritizing protein and carbohydrates, improving sleep quality, and addressing common micronutrient deficiencies through blood work, such as magnesium, vitamin D, and omega-3 status. Sponsors: Daily Fitness Insider Newsletter: https://flex-diet.kit.com/bfa1510fa8 Available now: Grab a copy of the Triphasic Training II book I co-wrote with Cal Deitz here. Episode chapters: 02:47 Meet Dr Nathan Jenkins 04:38 CrossFit Nutrition Reality Check 07:09 Leaving Tenure for Family 09:21 Back to Academia and Med Ed 11:29 Why Exercise Physiology Matters 14:36 Stress Tests Reveal Pathology 18:19 Max Testing and NIRS Setup 22:42 Raw Data Over Machine Outputs 24:18 Bohr Effect and Oxygen Delivery 28:09 Energy Systems in the Real World 33:05 Coaching Basics That Matter 35:40 Teaching Cardio From First Principles 36:36 Aerobic Base Reality Check 37:19 Cardio for Meatheads Pitch 39:13 CrossFit Endurance Breakthroughs 41:49 Fixing Time Domain Weakness 45:46 Pacing Like Froning Fraser 48:42 RAAM Gamesmanship Story 51:45 Pain Management Truths 53:23 VO2 Max Feels the Same 55:54 Suffering as a Skill 59:09 Cold Plunge Mindset Study 01:00:52 Caffeine Placebo and Belief 01:03:22 Heat Acclimation and 10K Prep 01:04:36 Metabolic Flexibility Lens 01:08:16 Teaching Diabetes Integration 01:10:56 Bloodwork Meets Flexibility 01:12:37 Where Fat Goes Wrong 01:15:07 Sustainable Deficit Strategy 01:16:34 Four Priorities Blueprint 01:17:21 Protein and Carb Targets 01:21:08 Sleep and Micronutrients 01:27:06 Omega-3 Testing Nuance 01:29:36 Wrap Up and Next Steps 01:31:52 Newsletter and Flex Diet Cert 01:33:20 Final Thanks and Subscribe Flex Diet Podcasts you may enjoy: Episode 344: Metabolic Adaptations, Lactate, and Training Smarter with Dr. Phil Batterson YouTube: https://youtu.be/PPZyO1nxSPA Episode 383: Body Composition, Strength Training, and Sustainable Habits with Martin Silva YouTube: https://youtu.be/p8oM0gW488U Connect with Dr. Jenkins: Website: https://www.drnathanjenkins.com/ Instagram: https://www.instagram.com/drnathanjenkins Get In Touch with Dr Mike: Instagram: Drmiketnelson YouTube: @flexdietcert Email: Miketnelson.com/contact-us Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this episode of the Flex Diet Podcast, I sit down with my friend Tracy Holemeyer (Uncontrollably Me, host of the Other Way to See It podcast) to talk about healing and performance through nervous system flexibility, somatics, and self-awareness, especially with how much stress people are carrying right now.  We dig into practical tools like orienting, grounding, the “starfish” drill, pendulation, and Tracy’s “core four” (soft eyes, relaxing the tongue, breath pacing for coherence, and soft knees), plus how posture and unconscious habits can shape mood and behavior. We also explore the value of community and coaching, how movement and sound (including humming, voo breath, and growling) can help regulate, and we finish with a thoughtful discussion on psychedelics, integration, and why support and discernment matter. Sponsors: Daily Fitness Insider Newsletter: https://flex-diet.kit.com/bfa1510fa8 Available now: Grab a copy of the Triphasic Training II book I co-wrote with Cal Deitz here. Episode Chapters: 02:59 Meet Tracy and Catch Up 04:46 Micro Breaks and Orienting 08:46 Starfish and Body Awareness 10:44 Joints Posture and Anxiety 17:37 Strategies Become Identity 21:00 Awareness Coaching in Practice 26:02 Coaching Community and Support 32:44 Social Media Validation Trap 36:13 Integrity and Business Alignment 39:39 Trauma Weight and Safety 41:57 Referrals Over Scarcity 43:07 Abundance Through Uncertainty 47:09 Money Purpose and Access 52:57 Capacity and Ongoing Stress 57:15 Pendulation and Core Four 01:03:00 Movement Urgency and Sound 01:08:55 Growling Music and Release 01:15:23 Healing as Defiance 01:16:59 Flow States and Community 01:18:23 Recreation With Real Stakes 01:20:13 Choosing Controlled Hardship 01:21:09 Healthy Stress Builds Capacity 01:23:34 Rewriting Trauma Responses 01:25:28 Psychedelics And Integration 01:34:07 Avoiding The Healing Shortcut 01:37:10 Where Memories Live 01:42:45 Four Tools For Stress 01:46:19 Finding Tracy And Closing 01:49:45 Podcast Wrap And Disclaimer Flex Diet Podcasts you may enjoy: Episode 354: How Shiftwave Reboots Your Nervous System w/ Dr. Jeff Rouse YouTube: https://youtu.be/XTPwIb3ZMxQ Episode 345: Sleep Like a Beast: Lessons from Jay Wiles and Jeffrey Durmer YouTube: https://youtu.be/8mVvceWn-Yw Connect with Tracy: Website: https://www.uncontrollablyme.com/ Instagram: https://www.instagram.com/embodiedsomatics Get In Touch with Dr Mike: Instagram: Drmiketnelson YouTube: @flexdietcert Email: Miketnelson.com/contact-us Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this episode of the Flex Diet Podcast, I sit down with human performance specialist and coach Rob Wilson for a wide-ranging conversation that spans music, coach education, and what it really means to train for performance longevity. We dig into Rob’s new book, The Check Engine Light: Tune In Your Body and Mind to Achieve Performance Longevity, and his work educating coaches through ALTIS and with special operations communities. Rob also shares why jiu-jitsu strength and conditioning still lacks clear performance standards and proposes building sport-specific frameworks (like lower-body clinching demands) before jumping to exercise selection. We talk grip strength vs endurance, avoiding redundancy and tendon issues, contra-specific training for durability, and why “recovery” isn’t the goal—adaptation is—especially in elite sport. Sponsors: Daily Fitness Insider Newsletter: https://flex-diet.kit.com/bfa1510fa8 Available now: Grab a copy of the Triphasic Training II book I co-wrote with Cal Deitz here. Episode Chapters: 02:41 Nineties Music Nostalgia 05:08 Seasonal Listening Habits 11:17 Teaching and ALTIS Work 13:25 Building BJJ Performance Frameworks 22:55 Grip Strength and Tendon Tradeoffs 26:51 Grip Training Hacks and Extensions 37:34 Transfer, Gait, and Fuzzy Sports 46:13 Compensation in Athletes and Aging 51:50 Warrior Fitness Reset 53:00 Check Engine Light System 54:27 Spiderweb Symptoms Explained 56:12 Eyes Unlock Performance 57:53 Stuck in Your Box 01:02:47 Logistics and Stakeholders 01:06:08 Effects Over Modalities 01:08:55 Recovery vs Adaptation 01:15:50 Wearables Need Context 01:19:41 Effort When Tired 01:25:50 Cold Plunge Mindset 01:30:14 Book Links and Wrap Up 01:31:07 Final Thanks and Disclaimer Flex Diet Podcasts you may enjoy: Episode 275: Mastering Combat Sports Conditioning Using Advanced Training Techniques with Coach James Tognarini YouTube: https://www.youtube.com/watch?v=t9Hc-VrsY4k&t=1s Connect with Rob: Book: https://www.thecheckenginelightbook.com/ Instagram: https://www.instagram.com/thecheckenginelight Website: https://www.wilsonhealthandperformance.com/ Get In Touch with Dr Mike: Instagram: Drmiketnelson YouTube: @flexdietcert Email: Miketnelson.com/contact-us Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this episode of the Flex Diet Podcast, I talk with my good buddy Chad Landers, veteran trainer, strength coach, and author of Building Strength and Muscle After 50, about how to keep gaining strength and muscle as you get older without falling off the “injury cliff.” We dig into why consistency matters most, how progress often drops in steps after injuries, and why smart modifications beat worshipping any single lift.  Chad shares lessons from coaching clients for decades, including balancing pressing with back work, using better technique (like pause benching), and building conditioning with tools like the fan bike, rower, and step mill. We also cover practical programming, tracking PRs beyond 1RM, and why it’s never “too late” to start training—especially after 50. Sponsors: Daily Fitness Insider Newsletter: https://flex-diet.kit.com/bfa1510fa8 Available now: Grab a copy of the Triphasic Training II book I co-wrote with Cal Deitz here. Episode Chapters: 03:31 Book and Aging Strong 05:21 Consistency and Injury Cliff 08:52 Modify Training for Joints 16:11 Bench Press Progress 18:29 Bench Tips and Ego 23:34 Back Work and Ratios 28:38 Programming and Cardio Intervals 32:17 Accountability and Habits 35:59 Cardio Gear Picks 37:19 Best Cardio Machines 38:44 Elliptical And Zone Two 39:33 Fan Bike Reality Check 41:04 Cheap Bike Trainer Setup 42:05 Interval Training Blueprint 44:28 StepMill For Drummers 46:09 Performers And Conditioning 49:49 Consistency Over Supplements 56:03 Why Write The Book 59:56 Tracking PRs With Logs 01:03:34 Coaching Hacks And Rehab 01:06:39 Where To Buy The Book 01:11:07 Podcast Wrap Up Disclaimer Flex Diet Podcasts you may enjoy: Episode 342: Balancing Nutrition and Social Life with David Page YouTube: https://www.youtube.com/watch?v=ojBnb3o3OrM&t=1s Episode 355:  The Stimulated Mind: Dr. Tommy Wood on Building a Better Brain Through Training, Tech & Physiology YouTube: https://www.youtube.com/watch?v=BeEEbTdZVNc Connect with Chad: Building Strength and Muscle After 50: https://us.humankinetics.com/products/building-strength-and-muscle-after-50 Instagram: https://www.instagram.com/chadlanders/ Website: https://pushprivatefitness.com/ Get In Touch with Dr Mike: Instagram: Drmiketnelson YouTube: @flexdietcert Email: Miketnelson.com/contact-us Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter

In this episode of the Flex Diet Podcast, I’m on the road and sit down with strength coach Martin Silva to talk about how to improve body composition, performance, and long-term health, especially for high-achieving clients in the 35–60 range. We get into unlearning a lot of the nutrition beliefs people bring in, why I still like keeping nutrition simple, higher protein, fewer ultra-processed foods, and how short-term tracking can build awareness without becoming a crutch. Martin also walks through how he structures coaching check-ins, his own background going from bodybuilding and restriction to a more health and strength-focused approach, and what actually works in the real world. We also cover programming, including full body vs upper/lower splits, single-leg work, squat and deadlift variations (I’m a fan of the trap/hex bar here), mobility priming, and how to monitor technique even when coaching online. Plus, we dig into stress, sleep, managing distractions (your phone is probably not helping), and a few rapid-fire tips—including “never miss twice.” Sponsors: Daily Fitness Insider Newsletter: https://flex-diet.kit.com/bfa1510fa8 Available now: Grab a copy of the Triphasic Training II book I co-wrote with Cal Deitz here. Episode Chapters: 02:21 Body Comp Framework 04:00 Nutrition Basics Protein 07:01 Adherence Tracking Habits 10:21 Check Ins Coaching System 13:28 Mindset Lessons Reverse Diet 15:01 Bodybuilding Backstory Shift 18:14 Performance First Training 20:47 Programming Frequency Splits 25:15 Mastering Compound Lifts 27:25 Squat Alternatives Single Leg 28:47 Deadlift Hinge Progressions 29:54 Hip Thrust Debate 30:42 Hip Thrusts for Athletes 31:30 Front Loaded Squat Options 33:09 Single Leg Strength Focus 34:18 Z Press and Pressing Variations 36:05 Mobility and Priming 37:57 Trap Bar Deadlift Preference 39:27 Stress and Sleep Routines 43:03 Phone Distraction Strategies 46:48 Four Tips for Body Comp 51:52 Mindset Never Miss Twice 52:43 Where to Find Martin 53:26 Wrap Up and Disclaimers Flex Diet Podcasts you may enjoy: Episode 365: Carb Cycling for Performance and Body Comp with Jon Heck YouTube: https://www.youtube.com/watch?v=19VSFiYWhVw Episode 358: Navigating Body Composition, Weight Loss & Real-World Coaching with Aram Grigorian YouTube: https://www.youtube.com/watch?v=f5NryXdButk&t=1s Connect with Martin: Instagram: https://www.instagram.com/martinsilvafitness/ Website: https://optimiseyourbody.transistor.fm/ YouTube: https://www.youtube.com/@Martinsilvafitness Get In Touch with Dr Mike: Instagram: Drmiketnelson YouTube: @flexdietcert Email: Miketnelson.com/contact-us Get the Daily Fitness Insider newsletter (free): https://www.miketnelson.com/newsletter