Kai Brenner
Fitness Writer
Younger men into the gym, gains, and evidence-based supplementation
Kai Brenner covers strength, muscle and supplementation for the gym crowd that wants gains AND receipts. He brings the energy of the weight room and the rigor of the research desk, and calls out broscience wherever he finds it.
Latest articles
The GLP-1 Reckoning: A Decade of Real-World Data on Gains, Eye Risks, and Faces
GLP-1s deliver durable fat loss and metabolic wins — but a maturing evidence base is also flagging ocular signals and structural changes worth knowing before you pin or pass.
GLP-1s Beyond the Scale: Muscle, Brain Pressure, and the Next Wave of Formulations
Semaglutide reshaped the conversation around obesity. The next round of data — from skeletal muscle to intracranial pressure to oral small molecules — is reshaping what comes next.
Exenatide's Heart Win Isn't Just the Sugar or the Scale
A fresh post hoc dive into EXSCEL says the cardiovascular payoff from a once-weekly GLP-1 isn't fully explained by better A1c, blood pressure, or bodyweight. Something else is doing work.
What GLP-1s Actually Do to Your Body: Weight, Muscle, and the Surgical Asterisk
Three new clinical analyses cut through the semaglutide and tirzepatide hype — quantifying real-world weight loss at one year, the muscle question lifters keep asking, and what happens when patients head into the OR.
GLP-1s Beyond Blood Sugar: The Quiet Case for Organ Preservation
The same peptide class that reshaped weight loss is now stacking evidence in kidney protection, fibrosis prevention, and transplant medicine. Here's what the data actually says.
GLP-1 Drugs Get a Reality Check: What Tirzepatide, Semaglutide, and Liraglutide Are Actually Doing
A wave of 2025 analyses is dissecting the real mechanisms behind the headline weight loss — and the picture is messier, smarter, and more interesting than the marketing.
What You Stir Into Your Whey Matters: Stevia May Be Undoing the Gut Wins
A new in-vitro colonic model says whey protein reshapes the gut microbiome of metabolic-syndrome adults — and stevia, the sweetener riding shotgun in half your tubs, blunts the effect.
GLP-1's Expanding Frontier: Type 1 Modeling and the Brown-Fat PET Surprise
GLP-1 receptor agonists keep pushing into new clinical territory. Two 2025 papers — a modeling review for type 1 diabetes and a case report where semaglutide lit up brown fat on a PET scan — hint at what's next.
GLP-1s Beyond the Scale: The Real Risk-Benefit Ledger for Lifters
Semaglutide-class drugs are rewriting cardiometabolic medicine — and quietly accumulating a safety file that gym-goers should actually read.
The New GLP-1 Frontier: Combo Stacks, Cardio Synergy, and the Oral Pill Race
GLP-1s aren't just a shred-cycle headline anymore. The next wave — liver-targeting combos, cardiovascular synergy with training, and oral delivery — is rewriting what these peptides can do.
Posture, Iron, and Movement Screens: What Military Science Reveals About Injury-Proofing Yourself
Four military training studies translate into a sharper playbook for serious lifters who want to keep training — and stop leaving gains on the physio table.
Sulforaphane and Curcumin: Two Plant Compounds Geroscience Is Watching
A new study suggests sulforaphane sharpens the body's response to exercise in older adults, while a quarter-century of curcumin research keeps circling the same translational wall: bioavailability.