Dr. Spencer Nadolsky and Karl sit down with Dr. Adam Auton, geneticist at 23andMe, to break down a brand new paper using data from over 27,000 people that identified specific genetic variants linked to how well GLP-1 medications work and how likely someone is to experience side effects. 23andMe has over 11 million people in their research database and used voluntary survey data on medication use, dosage, duration, weight loss, and side effects to match against genetic profiles at scale, making this one of the most powerful datasets anyone has brought to this question.

In this episode they cover how genome-wide association studies work and why scanning 600,000 genetic variants at once lets researchers find signals they never could have predicted in advance, why the first signal that jumped out of the data was a variant right in the GLP-1 receptor itself and why that was the moment the team knew they were on the right track, why the same variant that predicts better efficacy also predicts a higher risk of side effects and what that tells us about how the drug is being processed, why tirzepatide users showed a separate signal in the GIP receptor that modulates side effects rather than weight loss, why carrying both variants could make someone 14 times more likely to experience side effects on tirzepatide, why genetics explains roughly 10 percent of weight loss variation and what the other 90 percent looks like, why women tend to respond better than men and why diabetics tend to respond less well, what the future of this research looks like including who regains weight after stopping and whether those patterns are genetically predictable, and why heritability is a statistical measure that gets badly misunderstood even by clinicians.

The Docs Who Lift podcast distills and simplifies the complexities of exercise, medicine, and weight loss. Subscribe so you never miss an episode.

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5:37 PM

Dr. Spencer Nadolsky and Karl sit down with Dr. Henning Langer, PhD researcher at the Charité in Berlin and founder of his own muscle metabolism lab, to break down his newly published paper combining rodent and human data to look directly at what GLP-1 medicines actually do to skeletal muscle beyond what a DEXA scan can tell you. Dr. Langer spent time at Boehringer Ingelheim specifically studying skeletal muscle during obesity and anti-obesity treatment before bringing that work to his own lab, and this paper is one of the only studies to date that has looked at muscle directly rather than lean body mass as a proxy.

In this episode they cover why the step one trial's 40 percent lean mass loss figure may not be as alarming as it sounds and why most incretin trials actually land closer to the expected 25 percent, why lean body mass on a DEXA scan conflates muscle with glycogen, liver weight, and water in ways that overstate actual muscle loss, why the mice on semaglutide that looked the roughest in their cage ran the best on the treadmill to exhaustion, what mitochondrial protein changes in the proteome data suggest about a possible fatigue resistance benefit that cannot be explained by fat loss alone, how absolute muscle force tended to drop slightly while relative strength and endurance held up, what the human data from Nottingham showed about maximum voluntary contraction and knee extension force in patients on GLP-1 treatment, why the geriatric population is the next big unanswered question in this space, and why resistance training combined with high protein still cuts muscle loss in half and remains the most powerful lever available regardless of what the pharmacology does.

The Docs Who Lift podcast distills and simplifies the complexities of exercise, medicine, and weight loss. Subscribe so you never miss an episode.

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Dr. Spencer Nadolsky and Dr. Karl Nadolsky sit down with Dr. Stuart Phillips, senior author on the newly updated American College of Sports Medicine position stand on resistance training, to break down what 137 systematic reviews and over 30,000 participants actually tell us about building muscle, getting stronger, and improving function across the lifespan. The last version of these guidelines was published in 2009 and the science has come a long way, even if the fundamentals have not.

In this episode they cover why lifting weights twice a week is already getting most of the available benefit and three times is better but not by as much as you think, why the hypertrophy rep range is far broader than the classic 8 to 12 and what that actually means for your training, why getting stronger still requires lifting heavy things regardless of what anyone tells you, how power training is about moving with intentional velocity and why it matters more as you age than most people realize, why periodization showed no statistically significant advantage over non-periodized programs in the systematic review and what that means in practice, why eccentrically biased training produces slightly better muscle growth but is an optimization tool not a fundamental one, why time under tension does not have the evidence base people think it does, why blood flow restriction remains a niche tool rather than a strategic advantage, and why the best workout is simply the one you will actually show up and do consistently.

The Docs Who Lift podcast distills and simplifies the complexities of exercise, medicine, and weight loss. Subscribe so you never miss an episode.

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Dr. Spencer Nadolsky, Dr. Karl, and chief science officer Dr. Grant Tinsley sit down with Dr. Steven Heymsfield, physician at the Pennington Biomedical Research Center and lead author on the BELIEVE trial, to break down what happens when you combine bimagrumab with semaglutide and why over 90 percent of weight lost in the combination group was pure fat. Dr. Heymsfield has published over 600 peer reviewed articles and is widely considered one of the foremost body composition researchers in the world, and Grant Tinsley credits him as a foundational influence on his own work in the field.

In this episode they cover what bimagrumab actually is and how blocking the activin receptor causes muscle to grow, the origin story of the drug from Novartis to Versanus to Lilly and why sarcopenia research accidentally opened the door to obesity treatment, the nine group trial design and what it really boils down to, why the bimagrumab only group lost 7 percent of their weight entirely as fat without reducing food intake, the LDL cholesterol finding that has everyone talking and whether it actually matters, what happens to muscle and weight when you come off both drugs, why visceral adipose tissue practically disappeared in the antibody treated groups, the functional outcomes data including grip strength and physical activity scales, whether a subcutaneous version is coming, and what the future of this drug class looks like now that Lilly has deprioritized it.

The Docs Who Lift podcast distills and simplifies the complexities of exercise, medicine, and weight loss. Subscribe so you never miss an episode.

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Dr. Spencer and Karl Nadolsky bring on Dr. Alyssa Olenick, exercise physiologist and postdoctoral researcher in menopause and metabolism, to cut through the noise on one of the most misrepresented topics in women's health.

Dr. Olenick holds a PhD in exercise physiology, completed postdoctoral training focused on menopause and body composition, and is the founder of the Liss Method, a hybrid training program combining strength and endurance. She has been doing women-specific and sex-difference research since her master's degree and is one of the sharper voices pushing back on the wave of pseudoscience targeting women in the fitness space.

In this episode they cover what actually changes in body composition during the menopausal transition and what does not, why fitness status matters more than menstrual cycle phase or contraceptive use, how the fitness industry profits from pinkifying advice that was never women-specific to begin with, the truth about rep ranges and why effort matters more than the number, cortisol myths and why the adaptive stress response to exercise is not your enemy, and how to approach training adjustments during perimenopause without overcorrecting into low intensity fear-based programming.

No pseudoscience. No pink packets. Just the research.
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Takeaways:

Creatine is a naturally occurring compound that helps regenerate ATP, the energy currency of the cell.

Supplementing with creatine can enhance performance in high-intensity exercise but may not be beneficial for endurance activities.

The majority of creatine is stored in muscle, and supplementation can help fill those stores for better energy availability.

Creatine monohydrate is the most studied and effective form of creatine, and it's also the cheapest.

There is no need to cycle creatine; continuous use is safe and effective.

Creatine supplementation is generally safe, but individuals should inform their healthcare providers about its use.

The benefits of creatine are most pronounced in individuals engaging in high-intensity exercise.

Creatine does not directly build muscle; it requires exercise to be effective.

There is a misconception that creatine is harmful to the kidneys; it is safe for healthy individuals.

Creatine supplementation may have potential cognitive benefits, but more research is needed.

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Takeaways:
The 11-Minute Rule: Why blue light isn't the villain you think it is.

The Melatonin Mistake: Why "less is more" (and the exact dosage for success).

Trackers vs. Reality: When to throw away your Apple Watch or Oura Ring.

The Bedrock Principle: Why sleep is the lead domino for fat loss and metabolic health.

Sex & Sleep: The surprising biological difference in how men and women recover.

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Shelbys Book

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Takeaways:

Dr. Lucky Sekhon is a reproductive endocrinologist and author of 'The Lucky Egg'.

The pathway to reproductive endocrinology involves extensive training in OB-GYN and specialized fellowship.

Social media became a tool for Dr. Sekhon to combat misinformation during the pandemic.

Common myths in fertility include the idea that one can reverse the biological clock.

Understanding the fertility knowledge gap is crucial for patients seeking help.

Insulin resistance plays a significant role in fertility issues, especially in women with PCOS.

Fertility treatments should be evidence-based and tailored to individual needs.

GLP-1 medications can help regulate menstrual cycles and improve fertility outcomes.

Endometriosis can significantly impact fertility and requires tailored treatment approaches.

The importance of patient education in navigating fertility treatments cannot be overstated.

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Takeaways

Excellence is not a standard but a process of becoming.

Involved engagement means caring deeply about what you do.

The pursuit of excellence shapes you into a better person.

Consistency is key to achieving long-term goals.

It's important to align your pursuits with your values.

Youth sports can be beneficial but also harmful if not approached correctly.

Weight loss should shift from a focus on numbers to health and well-being.

Building a diverse identity can help prevent burnout in athletes.

The transition out of sports can be challenging due to identity loss.

Enjoying the process is more fulfilling than the end goal.

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Key Episode Takeaways

Oral Wegovy is real, but it’s not “just a pill version of the shot.” Absorption rules, dosing schedules, and patient selection matter a lot more than most headlines suggest.

Switching from injections to oral GLP-1s requires a plan. The transition isn’t one-size-fits-all, and dose timing, GI tolerance, and expectations need to be managed carefully.

Weight regain after stopping GLP-1s is common, but not universal. SURMOUNT-4 data shows large variability, reinforcing that biology, not willpower, drives outcomes.

Maintenance matters as much as weight loss. Some patients need continued therapy at lower doses, while others may maintain with lifestyle plus strategic medication use.

Stopping abruptly is usually the worst approach. Gradual transitions and realistic long-term strategies reduce rebound weight gain.

GLP-1s are chronic disease tools, not short-term fixes. Treating obesity like hypertension or diabetes leads to better outcomes and fewer surprises.

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Takeaways:

Dietary guidelines have evolved since the 1980s.

The food pyramid was introduced in 1992 and has influenced public perception.

New dietary guidelines emphasize healthy fats but retain some old recommendations.

There are contradictions in the new guidelines regarding saturated fat and protein intake.

The definition of processed foods remains vague and controversial.

The guidelines are intended for healthcare professionals, not consumers.

Public policy needs to align with dietary guidelines for effective implementation.

The emphasis on real food is not a new concept in dietary guidelines.

There is skepticism about whether the new guidelines will lead to meaningful changes in public health.

The conversation around dietary guidelines is often politically charged.

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