The peptide and GLP-1 conversation has reached a fever pitch. Walk into any wellness corner of the internet and you will find growth-hormone-releasing peptides being marketed as the new fountain of youth, GLP-1s being framed as the perfect drug for almost everyone, and an aesthetic of optimisation that promises more muscle, less fat, higher IGF-1, and a longer, leaner life. In this episode, I sit down with Dr Valter Longo to look at what the totality of the evidence actually says, and the case he makes is the most carefully constructed pushback against that worldview I have heard.
Valter is Professor of Gerontology at the University of Southern California and Director of the Longevity Institute at USC. He developed the Fasting-Mimicking Diet, has led foundational work on the growth hormone, IGF-1, insulin, and TOR axis across yeast, mice, and humans, and runs non-profit longevity foundation clinics in Europe and the United States that follow thousands of patients. He calls himself the anti-biohacker, and he makes that case using the same framework he applies to every drug, supplement, and intervention: what does a century of research, across yeast, worms, flies, mice, rats, and humans, actually tell us? What I really wanted from this conversation was the view from the inside, from someone who has been sitting with this biology for more than two decades and is not selling a compound at the end of it.
What We Cover:
- The growth-hormone-releasing peptides being sold as longevity tools, the bodybuilding history of the 1990s that seeded today’s market, and why every line of evidence, from dwarf mice to the Laron syndrome cohort in Ecuador to acromegalic patients, points the opposite way to the marketing
- A long, careful look at GLP-1s, including the body composition math that rarely gets discussed: roughly 3 kilograms of net fat loss but around 2 kilograms of lean mass loss across 3 to 4 years on a 100 kilogram person, with about 92 per cent of users having quit by year 3
- Why constant receptor stimulation, whether by drug or peptide, breaks the evolutionary harmony of the system, and why stacking a second drug to manage the side effects of the first is rarely the right move
- The optimal IGF-1 range from Valter’s recent meta-analysis, between 120 and 160 nanograms per millilitre, and the protein quantity, plant-to-animal ratio, methionine load, and 12-hour feeding window practices that keep most people there without supplementation
- The Fasting-Mimicking Diet across more than 47 clinical trials and over a million users, including the Stanford Crohn’s trial in Nature Medicine, the Miami ulcerative colitis work, the University of Rome chronic kidney disease trial that normalised proteinuria in all 13 patients, and the roughly 2.5-year biological-age reduction after three cycles using Morgan Levine’s BioAge clock
- Why the Harvard plant-versus-animal protein papers have been widely misread, what the data actually says about amino-acid profile and food matrix, and how Valter’s collaboration with Walter Willett, Edward Giovannucci, and Frank Hu’s group is reframing the story
- The case against ketogenic and very low-carb patterns for longevity, drawn from the Harvard cohorts, the Lancet U-shape paper, and the traditional high-carb diets of Okinawa, Japan, the Mediterranean, and Loma Linda, plus what it means for how much carbohydrate makes sense day-to-day
- Where AI fits into all of this, including Valter’s view that synthesising the totality of evidence is the antidote to the cherry-picking that drives most biohacker marketing, and why we both think the next few years will look very different
Valter’s argument is not that drugs and peptides have no place. It is that the bar for putting something into the human system long-term should be set by the totality of the evidence, not by anecdote and a self-selected demographic of healthy young men. The longevity diet, the Fasting-Mimicking Diet, and a 12-hour eating window are not as marketable as the next compound being sold on a forum, and they happen to be where the strongest evidence sits.
To follow more of Dr Valter Longo’s work, visit his website, find him on Instagram, and explore the work of the Create Cures Foundation, the Valter Longo Foundation, the Longevity Technology Institute, and the European Longevity Institute through his published research and his book The Longevity Diet.
- Intro (00:00)
- The Peptide Boom and What Is Actually Being Sold (00:01)
- GLP-1s: 92 Per Cent Drop-Out and the Body Composition Math (00:02)
- Why Stacking Drugs Is Not the Answer (00:08)
- GLP-1s vs the Mediterranean Diet on Mortality (00:11)
- The Fasting-Mimicking Diet Reverses Western-Diet Damage (00:13)
- What Growth Hormone Releasing Peptides Actually Are (00:15)
- Snell, Ames, and Laron Dwarf Mice and the Longevity Signal (00:18)
- The Laron Syndrome Cohort in Ecuador (00:24)
- Acromegaly and the Cost of High Growth Hormone (00:28)
- The Pulsatile IGF-1 Argument vs the Cigarette Defence (00:34)
- The TOR Pathway, Rapamycin, and Why Upstream Matters (00:42)
- The Optimal IGF-1 Range: 120 to 160 ng/mL (00:50)
- Plant vs Animal Protein, Properly Read (00:57)
- Amino Acids, Methionine, and the Hypothalamus (01:03)
- The Anti-Keto Case from Okinawa to Loma Linda (01:08)
- AMPK, FOXO, Autophagy, and Why Fasting Works (01:11)
- Chemotherapy, Beta-Cell, and Kidney Regeneration Trials (01:15)
- Stanford Crohn’s, Miami UC, and Rome Kidney Disease (01:22)
- Biological Age Reduction After Three FMD Cycles (01:25)
- FMD Plus a Short-Acting GLP-1 (01:29)
- FMD Safety Across More Than a Million Users (01:31)
- White Rice, White Bread, and the Pasta Defence (01:41)
- The Longevity Diet: Eat More, Eat Better (01:43)
Resources and links:
Subscribe and stay connected:
Subscribe to The Proof on YouTube, Apple Podcasts or Spotify to ensure you never miss an episode. And don’t forget to follow me on Instagram and X for more insights and updates.
This episode is brought to you by:
38TERA
Consider 38TERA’s DMN prebiotic supplement a daily multivitamin for your gut. Formulated by yours truly and gastroenterologist Dr Will Bulsiewicz. Use code THEPROOF for a discount at checkout.
38Tera ships to the United States, Australia, and New Zealand.
Pique
Pique’s Nandaka combines fermented Pu’er tea, full-spectrum Reishi, ceremonial cacao, and L-theanine for calm, sustained energy without the coffee crash. Unlock 20% off and establish your powerful foundation for sustained well-being at Piquelife.com/SIMON.
Pique ships within the U.S. and to Australia, Canada, and select EU countries.
Function Health
Take charge of your health with advanced blood testing and personalised insights. Function Health offers a practical way to track key health markers such as cholesterol, blood sugar, and more. Learn more and join at functionhealth.com/simonhill for a $25 credit toward your membership. Only available to those living in the United States.
Function Health ships to 48 U.S. states, excluding Rhode Island, Hawai‘i, and Puerto Rico.
Truemed
Truemed helps qualified customers use pre-tax HSA or FSA dollars on health-related products like fitness, recovery, and sleep tools, often saving around 30% on average. Visit Truemed.com to see what qualifies. This is hands down the best way to make the most of your health dollars.
IM8
With 92 nutrients, including Vitamin B12, Iodine, Selenium and Vitamin D, in highly absorbable forms, IM8 Daily Essentials is the perfect all-in-one daily multi-vitamin to ensure you meet your daily micronutrient needs. IM8 is offering an exclusive 10% off your first order with a free welcome kit when you enter the promo code SIMON at checkout on im8health.com.
IM8 ships to 27 countries including the U.S., Canada, the U.K., Australia, and many regions across Europe, Asia, and South America.
WHOOP
WHOOP, the most advanced fitness and health wearable available. Your personalised fitness and health coach to recover faster, sleep better, and train smarter. Claim your first month free on join.whoop.com/simon.
WHOOP ships to 56+ international markets, including the US, Canada, most of Europe, Australia, New Zealand, UAE, Singapore, and parts of Asia.
More about Valter Longo
Dr Valter Longo is Professor of Gerontology and Biological Science and Director of the Longevity Institute at the USC Leonard Davis School of Gerontology in Los Angeles. He is internationally recognised as a leading voice on longevity and age-related disease. After extending the lifespan of a simple organism tenfold by combining fasting and genetic mutations and discovering one of the most important pathways in longevity research, his group identified an equivalent mutation in humans associated with protection from cancer, diabetes, cognitive decline, and cardiovascular damage. His laboratory later described and developed the Fasting-Mimicking Diet and published on its effects on multi-system stem cell activation, reprogramming, and regeneration. That work has now produced more than 30 clinical trials, including studies showing that FMD cycles can reduce biological age, drive diabetes regression, and potentially improve outcomes in cancer patients. His book The Longevity Diet has been translated into 26 languages and distributed in 40 countries. In 2018, Time magazine named him one of the 50 most influential people in healthcare. He is the President of the non-profit Create Cures Foundation and the Longevity Technology Institute in the US, the Valter Longo Foundation in Italy, and the European Longevity Institute. He is a Highly Cited Researcher (2021 to 2025) and ranks among the top 1:1000 most-cited scientists globally.
