THE SIGNAL

Issue 001 - March 14, 2026 - GLP-1s & SLEEP WEARABLES

THE SIGNAL

Scientific Intelligence for Men's Health & Performance

A FeltovichFit Publication · Collegium of Order & Flow

Week of March 9–14, 2026 · Issue 001 · Andy Feltovich, CISSN · CSCS · StrongFirst Elite

Each week, The Signal cuts through the noise in health, performance, and science:

What to watch?

What to ignore?

What’s “news” but isn’t new?

The Signal analyzes each topic with the IICE Framework:

Incentives. Who is being asked to believe what? Why? And why now?

Impact. Does it move the needle?

Context. How does it relate to other evidence within the discipline and across disciplines, both currently and historically?

Epistemic Authority. Is the argumentation sound and valid?

This week’s deep dives cover GLP-1 drugs and the addiction signal no one is talking about, and the real story on sleep wearables.

▶ What to Watch

Watch 1

GLP-1 Drugs: The Addiction Signal — and the Muscle Loss Nobody Is Talking About

Why It Matters
A retrospective cohort study of 606,434 U.S. veterans found that GLP-1 receptor agonists reduced the risk of new substance use disorders by 14–25% across alcohol, opioids, cocaine, and nicotine — and cut drug-related deaths in half among patients with existing addiction. GLP-1 receptors are expressed in the brain’s reward circuitry, and the same dopaminergic dampening that blunts food cravings appears to blunt cravings for addictive substances.

Signal Strength
This story received multi-channel confirmation in the same week: peer-reviewed BMJ data, NPR national coverage, and an FDA warning letter to Novo Nordisk for failure to report serious adverse events — including patient deaths — within the required 15-day window. The signal you are not hearing: the NEJM STEP 1 trial found that roughly 40% of weight lost on semaglutide is lean mass, not fat. For the executive male over 40, that is a body composition problem on a slow timer.

Prediction
GLP-1 agonists as a drug class are unprecedented in scale and scope. The trajectory will continue due to the economics of pharma, the intractability of obesity, and the popular and political push for expanded coverage. They’re also unprecedented in potential side effects — known and unknown. At minimum, structured resistance training and nutrition are mandatory adjuncts to any GLP-1 therapy. See deep dive below.

Headlines: BMJ, Mar 4, 2026 · NPR, Mar 5, 2026 · FDA Warning Letter, Mar 5, 2026

Watch 2

Wearables + HRV + Sleep Tracking — The Data Is Ready. The Interpretation Isn’t.

Why It Matters
The executive cohort over-indexes on device ownership and under-indexes on acting on the data. HRV, sleep quality, and resting heart rate together paint a daily readiness picture that changes what you should do Monday morning — if you know how to read it.

Signal Strength
ACSM ranked wearable technology the #1 fitness trend for the fifth consecutive year, surveying 2,000 clinicians and exercise professionals. Oura Gen 3 validation studies are approaching the limits of what the technology can achieve for assessing sleep stages.

Prediction
We are approaching the limits of consumer wearable technology. The next frontier is not better hardware — it is interpretation — and wisdom, knowing when not to use the data. The practitioners who can translate a readiness score into a sound training decision and counsel clients and patients on their interpretation and proper use will own the next decade of performance coaching.

Headlines: ACSM Top Fitness Trends 2026

Watch 3

Testosterone and Men’s Hormonal Health — The Space Nobody Is Doing Honestly

Why It Matters
Population-level testosterone has declined roughly 1% per year independent of aging, a trend documented across three decades in the Massachusetts Male Aging Study. The 40+ executive cohort is the primary affected demographic. The information space is dominated by TRT clinic marketing on one end and bro-science on the other, and nobody is giving this audience rigorous, unconflicted analysis.

Signal Strength
This story is growing quietly across clinical and social channels, under-covered relative to GLP-1, and represents a high pain point for this audience. Lifestyle interventions — sleep quality, progressive strength training, stress management, and body composition improvement — move the needle meaningfully before TRT is warranted.

Prediction
The men’s hormone space will bifurcate: TRT mill clinics versus evidence-based, lifestyle-first protocols. The Signal is planting a flag on the latter.

Headlines: Travison et al., JCEM 2007

✕ What to Ignore

Ignore 1

RFK / Food Dyes Ban — Policy Noise, Not Science Signal

Why It’s Spiking
Political momentum from the MAHA movement has produced real legislative action: West Virginia became the first state to ban synthetic dyes, and roughly 40% of packaged food companies have made voluntary reformulation commitments.

Why It’s Noise
Reuters found that almost none of those companies have actually reformulated their products. The behavioral literature on synthetic dyes in adults is essentially nonexistent, and regulatory action does not equal scientific validation. If you eat real food, this problem is already solved.

What Would Change My Mind
Double-blind RCTs showing consistent behavioral or physiological effects at real-world exposure levels in adults.

Headlines: Reuters, Jan 28, 2026 · KFF Health News

Ignore 2

Beef Tallow Skincare / Carnivore Beauty

Why It’s Spiking
This is a classic TikTok meme cycle: a simple, counterintuitive claim that is photogenic and easy to film. The format rewards novelty, not evidence.

Why It’s Noise
No peer-reviewed dermatology literature supports topical tallow as a therapeutic intervention. The American Academy of Dermatology consensus is unchanged. High social velocity, zero clinical signal, and no relevance to this audience’s performance goals. See Further Reading below for the full history of beef tallow’s 180-degree whipsaw from culinary villain to supposed “superfood.”

What Would Change My Mind
A single RCT from a credible dermatology institution demonstrating benefit over a controlled comparator.

Ignore 3

Slow Wellness / The Over-Optimization Backlash

Why It’s Spiking
The Global Wellness Summit named it a top 2026 trend, luxury brands including Nike and On Running are repositioning around “softness,” and TikTok somatic release content is generating significant traffic.

Why It’s Noise
The Blue Zone literature does confirm that high-longevity populations are characterized by high-frequency, low-intensity activity and strong familial and social bonds. What it also shows is that their success is the result of lifestyle as a permanent, organic backdrop — not micro-dosed, expensive lifestyle bolt-ons. The product being sold here is expensive experiences and aesthetic repositioning. Those are not the same thing.

What Would Change My Mind
If a RCT or even a respectable epidemiological survey study shows efficacy on par with known needle-movers like sleep, exercise, and nutrition — or even anecdotal evidence about Blue Zones.

Headlines: Global Wellness Summit, Future of Wellness 2026

↻ What’s “News” but Isn’t New

Not New 1

Fibermaxxing — Fiber Is the New Protein

Current Trend
TikTok is driving fiber-focused product launches across grocery and beverages, with CNN, Good Housekeeping, and Whole Foods positioning fiber as 2026’s breakout nutrient. The GLP-1 hook generating the most coverage: natural fiber stimulates endogenous GLP-1 production.

Historical Analog
The core fiber science — LDL reduction, blood sugar stabilization, gut microbiome support — has been established since Burkitt and Trowell in the 1970s. FDA dietary fiber recommendations have moved negligibly in 30 years.

The Signal
This is a big bag of nothing for anyone who’s been following me. With a whole-foods-first diet, fiber takes care of itself and requires no extraordinary attention. Excessive fiber impedes nutrient absorption, slows gastric emptying (important for training), and causes gastric distress. Artificial “fiber” is a full-stop no-go: some FDA-permitted compounds labeled as fiber have been implicated in painful bezoars — indigestible masses that can require surgery in extreme cases. See Further Reading below.

Headlines: CNN, Jan 25, 2026 · Kerry Health & Nutrition Megatrends · FeltovichFit: “Fiber Frenzy”

Not New 2

Zone 2 Cardio for Longevity — Soviet Endurance Science Returns

Current Trend
Another big bag of nothing for anyone who’s been following me. We’re hearing about it because it was expounded from Mount Sinai by — since diminished — former longevity demigod Peter Attia. Thomas DeLauer and YouTube educators have since amplified it to a new generation of athletes and executives.

Historical Analog
The Soviets — especially Verkhoshansky — solved the riddle of anaerobic threshold training 50+ years ago. Soviet sports science and East German endurance programs established the metabolic underpinning of low-intensity training in the 1960s–80s. Maffetone formalized the fat-burning zone in the 1980s. This principle is 60 years old.

The Signal
The key for performance isn’t how much O₂ you can take in (VO₂max), but how much work you can do before you go anaerobic — your anaerobic threshold. A legitimate VO₂max test is not easy, not fun, and potentially dangerous: any time you push the heart that hard, it can break. Anaerobic threshold testing can be done anywhere. Train, then try to recite the Pledge of Allegiance. If you can — still aerobic. If you can’t — you’re anaerobic. Yes, VO₂max is correlated with longevity (Mandsager et al., JAMA 2018). Should you be testing and targeting it? No.

Headlines: NYT, Feb 19, 2025 · GQ, Jan 24, 2026

Not New 3

Neurowellness / Nervous System Regulation

Current Trend
The Global Wellness Summit named nervous system regulation a top 2026 trend. Polyvagal theory is entering mainstream consumer wellness, and TikTok somatic release content is going viral — largely to an audience with no idea the underlying theoretical framework is under serious scientific challenge.

Historical Analog
This is Polyvagal Theory (Porges, 1994), Somatic Experiencing (Levine, 1970s), and MBSR (Kabat-Zinn, 1979) in new consumer packaging. In February 2026, Grossman and 39 co-signatories published in Clinical Neuropsychiatry declaring Polyvagal Theory “untenable” as a mechanistic account of autonomic function.

The Signal
The tools work. Breathwork, HRV biofeedback, and MBSR have strong RCT outcome data independent of whether the polyvagal mechanism is correct. The theory is contested. The applications are not. See Further Reading below for Porges’ primary texts.

Headlines: Global Wellness Summit, Future of Wellness 2026

■ Deep Dive — Issue 001

GLP-1 Drugs and Addiction — The Unexpected Signal

What a 600,000-person study means for the future of addiction medicine, the economics of drug development, and why the muscle loss story matters more than the weight loss headline.

A retrospective cohort study of 606,434 U.S. veterans — the largest observational study of its kind — found that GLP-1 receptor agonists reduced the risk of new substance use disorders by 14–25% across alcohol, opioids, cocaine, and nicotine, and cut drug-related deaths in half among patients with existing addiction.^[1] This is not a randomized controlled trial, but at 600k participants across multiple substances, the signal is hard to dismiss. Mechanistically, it makes sense: GLP-1 receptors are expressed in the brain’s reward circuitry, and the same dopaminergic dampening that reduces food cravings appears to reduce cravings for addictive substances.

A note on mechanism: GLP-1s are not a substitute for benzodiazepines in alcohol detox or methadone in opioid maintenance. They don’t touch withdrawal physiology. The signal is in what happens after detox: reduced craving, reduced relapse, reduced harm — across multiple substances simultaneously. That cross-substance effect is what makes this genuinely novel. Current addiction drugs (naltrexone, acamprosate) don’t work that way.

The incentives are clear: Novo Nordisk’s U.S. patent on semaglutide expires in 2032. The substance use disorder treatment (SUD) market is $42 billion annually — with only 2% penetration, the percentage of eligible patients currently prescribed any medication. An FDA approval for addiction wouldn’t just open a new revenue category — it would build a clinical moat.^† Generic biosimilars can only copy approved indications. Every new pathology Novo and Lilly can lock in before the patent cliff forces generics to run their own expensive trials before they can compete. Eli Lilly is already running two Phase 3 trials of a dedicated GLP-1 addiction compound. The race is on.

The GLP-1 revolution was never just a drug launch. It was a class launch — the first since statins redrew cardiovascular medicine in the 1990s — and unlike statins, it’s a class launch across multiple disease categories: obesity, diabetes, addiction, neurodegeneration. The scope and scale of such conquest makes the side effects — known and unknown — that much more troubling. One of the more well-known, short-term, and troubling side effects is that approximately 40% of weight loss comes from lean muscle — not fat, as confirmed by multiple randomized controlled experiments.^{[2, 3]} The fix is not complicated: lifestyle modification as a first line of defense, strategic use of GLP-1 agonists only when necessary — and structured resistance training and nutrition — including adequate protein — always.

The IICE read: The scale and scope of GLP-1s will increase. (1) Every new approved indication builds a clinical moat against generics — biosimilars can only copy what’s been approved, so Novo and Lilly are racing to lock in pathologies before the patent cliff. (2) GLP-1s are a lawnmower strategy — they only work if you keep using them. That means recurring, potentially lifetime revenue. (3) Pressure on employee benefits programs to expand coverage will intensify. (4) The obesity epidemic will only end when the time and dollar cost of being obese become prohibitively expensive — the same mechanism through which the last successful widescale public health campaign, the anti-smoking campaign, worked. Until there is public and political appetite for similarly invasive measures, obesity — and GLP-1s — will persist. See Further Reading below for the history and political economy of the obesity epidemic.

^† In investment language, a moat is a durable competitive advantage that protects profits over time — the term originates with Warren Buffett and is formalized in H. Brilliant and J. J. Collins, Why Moats Matter: The Morningstar Approach to Stock Investing (Wiley, 2014). The strategic underpinning is M. E. Porter’s Five Forces framework, which identifies barriers to entry as one of the five forces that determine industry profitability — see M. E. Porter, On Competition (Harvard Business Review Press, Updated ed., 2008).

■ Deep Dive — Issue 001 (continued)

Sleep Wearables: Good Servant — Poor Master

Sleep trackers are useful tools. They are not polysomnography. Here is what they actually measure, what the science says about what they get right, and why knowing the difference matters more than your sleep score.

We’re entering the second stage of sleep wearables. The first stage was making scientifically validated metrics commercially feasible. The second stage will be interpretation and wisdom — knowing not just how to use the metrics, but when. But first, a whirlwind recap of how we got here.

The Gold Standard You Don’t Have

Electronic sleep measurement isn’t new. The discipline was pioneered by Nathaniel Kleitman in 1937 with the use of electroencephalography to record brain activity during sleep.^[4] Since then, sleep scientists have progressively added more measuring devices to more body parts to better triangulate and taxonomize the physiological states that are collectively known as “sleep”:

Electro-oculography (EOG) — eye movement, which led to the discovery of Rapid Eye Movement (REM) sleep^[5]
Electromyography (EMG) — muscle tone
Electrocardiography (ECG) — cardiac rhythm and pulse oximetry

That bundle of laboratory measurements is collectively known as polysomnography (PSG) — the gold standard — which allows a trained practitioner to score every 30-second epoch of your night into one of five stages: Wake, N1, N2, N3 (slow-wave/deep), and REM.

(William Dement, Kleitman’s student and progenitor of that nomenclature, joked that had he known those terms would persist — Wake, N1, … REM — he would’ve thought of something sexier.)

Your Oura Ring, WHOOP strap, or Apple Watch does none of that. The breakthrough that made wearables feasible came in the 1970s with the advent of wrist actigraphy — motion detection — followed by skin temperature and photoplethysmography (PPG), the optical heart rate sensor on the back of your ring. Wearables combine those measurements with proprietary algorithms to infer what sleep stage you might be in — not the same league as PSG. As Brandon Marcello jokes: the gap in error in guessing sleep stages is the difference between a DEXA body composition scan and asking someone across the room to guess your body fat percentage.^[6]

What Do Sleep Wearables Actually Do?

The following is adapted from an article by sleep physician and FeltovichFit Podcast guest Dr. Muhammad Usama.^{[7, 8]} For sensitivity — whether true sleep was recorded as such — consumer wearables perform reasonably well. Oura Ring Gen 3 shows approximately 94% sensitivity for sleep detection. WHOOP is in the same range. The wheels come off with specificity — distinguishing quiet wakefulness from actual sleep. Fitbit Inspire 2 clocked 94% sensitivity but only 13% specificity in one validation, meaning it logged nearly every quiet period as sleep. If you lie awake — but don’t move — at 3 AM for 40 minutes, your tracker doesn’t know it, and your reported sleep total is fiction. A 2025 meta-analysis of 24 studies found that popular wearables underestimate total sleep time by roughly 17 minutes and sleep efficiency by 5%, while overestimating wake-after-sleep-onset by about 13 minutes compared to PSG.

Four-stage scoring (light, deep, REM, wake) is where the wheels fall off for the reasons mentioned. The best-performing consumer devices show 75–80% agreement with PSG. Oura Ring Gen 3 showed stage-scoring accuracy between 75–91% depending on the stage — the best peer-reviewed numbers in the consumer space. WHOOP showed approximately 64% overall agreement with PSG on four-stage scoring. The Apple Watch Series 8 could distinguish sleep versus wake adequately but fared poorly on estimating sleep stages.

PSG vs Consumer Wearables comparison table

The Fatigue Science ReadiBand — a technology representing $37 million in DoD-funded research investment and 25 years of development — achieves approximately 93% agreement with PSG, making it the most validated device in the consumer-adjacent market. However, it’s expensive: $649 for the device and a one-year subscription, plus $599 for a 12-month renewal — and the app isn’t as good as Oura’s.

Orthosomnia: The Word You Need to Know

Knowledge is knowing a tomato is a fruit. Wisdom is knowing not to put it in a fruit salad.

You can know your deep sleep percentage down to a decimal point and make yourself worse. Clinicians have a name for this: orthosomnia — a preoccupation with optimizing tracker data to the point where the monitoring itself disrupts sleep. The patient extends time in bed to chase a higher efficiency score, which — counterproductively — typically lowers efficiency. The anxiety about the score impairs sleep onset. The vigilance required to monitor your own wakefulness is neurologically incompatible with falling asleep. If you are the kind of person who optimizes everything, you are at elevated risk for this. Wearables are an adjunct to sleep hygiene — not a substitute or scorecard for it.

Three Questions That Don’t Require a Wearable

Before you interpret a single score from any device, answer these honestly:

Can you fall asleep at roughly the same time each night without pharmacological help — no alcohol, no OTC drugs, no prescription sleep aids?
Do you wake up on time, refreshed, without an alarm clock?
Can you get through the day without depending on stimulants?

If you answer yes to all three, your sleep is functioning. The wearable can add texture. If you answered no to any of them, no device will fix that. And the device may, in fact, distract you from fixing it.

The IICE read: Wearables are converging to the theoretical limit of what can be achieved without full PSG in a sleep lab under a trained practitioner. Fatigue Science is the “best” and offers customization — useful if, for example, you own a heavy equipment company and need to ensure operators are rested for safety and liability purposes. Otherwise, Oura is sufficient and comes with a better price and app. Assess the score in conjunction with how you’re feeling and behaving, and understand that wearables can only approximate sleep stages. If a wearable says you’re sleeping well but you wake up exhausted, believe your body. The wearable watches you sleep. It doesn’t sleep for you. Last, it bears repeating: do not try to diagnose or treat obstructive sleep apnea (OSA) or any other sleep disorder with a wearable.

■ References · Further Reading · Additional Resources

References

[1] M. Cai, T. Choi, Y. Xie, and Z. Al-Aly, “Glucagon-like peptide-1 receptor agonists and risk of substance use disorders among US veterans with type 2 diabetes: cohort study,” BMJ, vol. 392, e086886, Mar. 2026. https://doi.org/10.1136/bmj-2025-086886

[2] D. Pantazopoulos, E. Gouveri, D. Papazoglou, and N. Papanas, “GLP-1 receptor agonists and sarcopenia: Weight loss at a cost? A brief narrative review,” Diabetes Res. Clin. Pract., vol. 229, p. 112924, Nov. 2025. https://doi.org/10.1016/j.diabres.2025.112924

[3] J. P. H. Wilding et al., “Once-Weekly Semaglutide in Adults with Overweight or Obesity,” N. Engl. J. Med., vol. 384, no. 11, pp. 989–1002, Mar. 2021. https://doi.org/10.1056/NEJMoa2032183

[4] M. H. Kryger, T. Roth, and C. A. Goldstein, Kryger’s Principles and Practice of Sleep Medicine, 7th ed. Philadelphia: Elsevier, 2022. Hardcover Kindle

[5] W. C. Dement, “Knocking on Kleitman’s Door: The View from 50 Years Later,” Sleep Medicine Reviews, vol. 7, no. 4, pp. 289–292, 2003. https://doi.org/10.1053/smrv.2003.0279

[6] B. Marcello, “Sleep – The Only True ‘Fix-All’ for Health and Performance,” NSCA, May 15, 2020. [Online]. https://www.youtube.com/watch?v=WKt2LoHaCp4

[7] A. Feltovich, “Sleep as a Superpower: Optimizing Rest, Wakefulness, and Longevity with Dr. Muhammad Usama,” FeltovichFit Podcast, 2025. Spotify

[8] M. Usama, “Can Wearables Truly Transform Sleep Health, or Are We Just Watching Ourselves Sleep?” LinkedIn Pulse, Jun. 18, 2025. LinkedIn