Metabolic Health & Fitness

Editorial illustration of the gut's L-cells releasing the body's own GLP-1 beside a faint medication pen, showing the body already makes the hormone the drugs imitate — DrFitzNutrition.com
How to Increase GLP-1 Naturally: What Actually Moves It
Your gut secretes the same GLP-1 that Ozempic imitates after every meal. A physician and exercise physiologist breaks down what actually raises it, why protein is the lever that fades,... Read more...
How to Improve Insulin Resistance: What Actually Works
A physician explains what insulin resistance actually is, why a normal glucose test can miss it for a decade, and the one lever that improves it most — muscle contraction, and the mechanism behind why it works even when insulin doesn't. Read more...
Insulin Resistance Symptoms: The Signs Most People Miss
A physician explains the recognizable signs of insulin resistance — the fatigue, cravings, and visible skin changes that show up years before any lab does. Learn which symptom clusters carry real diagnostic weight, and why "normal" bloodwork can still miss the problem. Read more...
How to Reverse Insulin Resistance: A Physician's Mechanism-Level Guide
A physician's mechanism-level guide to reversing insulin resistance. What it actually is at the cellular level, what the DiRECT, DIADEM-I, and Virta trials proved about remission, and the realistic timeline — weeks for fasting glucose, months for HbA1c. Mechanism-first, evidence-grounded, no hype. Read more...
Visceral Fat vs Subcutaneous Fat: A Surgeon's Mechanism Guide
A peripheral nerve surgeon explains the real difference between visceral and subcutaneous fat, why portal vein anatomy makes one uniquely dangerous, and what the recent literature shows actually reduces it. Mechanism-first, evidence-based, no hype. Read more...
Why Does Weight Loss Plateau? The Metabolic Adaptation Explanation
A peripheral nerve surgeon breaks down the real physiology of weight loss plateaus. What adaptive thermogenesis actually is, why leptin and T3 drop when you diet, why aggressive deficits plateau faster, and the evidence-based strategies that actually break through — grounded in the Minnesota Starvation Experiment, the Biggest Loser follow-up, and the MATADOR trial. Read more...
Hyperinsulinemia, Weight Loss, and Fat Loss: Why Calories Aren't Enough
Cutting calories and still not losing body fat? Your insulin level — not your willpower — may be the real gatekeeper. This article walks through how chronically elevated insulin locks stored fat in place at the cellular level, what the RCT evidence shows about insulin-targeted fat loss strategies, and why fasting insulin may be a more useful biomarker than the scale. Read more...
Collagen for Hair and Nails: What the Trials Actually Show
The clinical trial data on collagen for hair and nails is more specific than most people realize. Dr. Fitzmaurice breaks down the peer-reviewed evidence — including a 31% increase in hair follicle cell proliferation, a 37.3% reduction in shedding, and a 42% decrease in broken nails at just 2.5g per day — along with the biological mechanism, realistic timelines, and a practical protocol. Read more...
Collagen for Skin: What the Science Actually Shows (And the Honest Timeline)
Collagen supplements have more clinical evidence behind them than most brands admit — and a longer timeline than most marketing suggests. Dr. Fitzmaurice breaks down the fibroblast mechanism, what 26 randomized controlled trials actually show about hydration and wrinkle reduction, the honest funding bias caveat, and the week-by-week timeline for realistic results. Read more...