XY Files

Evidence-based articles on testosterone, men's health, fitness, longevity, and sexual health.

Editors' picks

Healthy carbonated drinks: The science behind the switch for men

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Jan 13, 2026 · 9 min read

Switching from sugar-sweetened soda to low- or no-sugar functional carbonated drinks removes the liquid fructose hit that drives insulin resistance and visceral belly fat (which can suppress testosterone) and can add prebiotic fibers like inulin that feed beneficial gut bacteria such as Bifidobacteria. “Healthy” on the can isn’t a guarantee—here’s how the key ingredients actually ...

Joe Rogan’s 2025 stack: Onnit creatine 5g, what science says

Dr. Bruno Rodriguez, DPT, CSCS: Strength, Recovery, and Physical Therapy Expert

Dec 30, 2025 · 10 min read

Creatine monohydrate is the most consistently performance-boosting supplement in Rogan’s stack because it raises muscle phosphocreatine to regenerate ATP during high-intensity training, while most OTC “testosterone boosters” and trendy biohacks are largely hype without a true deficiency or prescription therapy. Rogan has also talked about keeping it simple with “5 grams” of creatine per day, ...

What happens if we release sperm daily? What science says about testosterone, muscle, and men’s health

Dr. Alexander Grant, MD, PhD: Urologist & Men's Health Advocate

Dec 11, 2025 · 13 min read

Wondering what happens if we release sperm daily? For most healthy men, frequent ejaculation is safe and does not drain testosterone, kill muscle gains, or wreck long-term health — but there are a few important exceptions you should know about. “For the average healthy man, ejaculating every day is more of a lifestyle choice than ...

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Latest medical insights

Best immunity boosting foods for men: What to eat to support your immune system year-round

The best immunity boosting foods are the ones that reliably provide the micronutrients and bioactive compounds your immune cells use to build barriers, signal threats, and resolve inflammation. This guide breaks down the highest-impact foods and shows how men can turn them into a simple, repeatable “immunity plate” for work, travel, and training. Written by: ...

Do weight loss supplements work for men? Separating the science from the scam

The best weight loss supplements for men are the ones with human evidence, modest expectations, and a clear mechanism — and green tea extract is one of the few that consistently shows a signal in research. This guide breaks down what “works” really means, how to use supplements safely, and what numbers to track so ...

Function Health testosterone results: What abnormal labs mean and what to do next

Function Health testosterone results can be a useful starting point, but “out of range” does not automatically mean you need TRT, and normal numbers do not automatically mean your hormones are fine. This guide shows men how to confirm low testosterone, interpret free testosterone, and choose the safest next steps with a clinician. By Plain ...

Keto diet and CGM: What your glucose level can look like and how to avoid reverse metabolic inflexibility

On a ketogenic diet, CGM traces usually show a lower, flatter 24‑hour glucose curve, while a rare high‑carb meal can cause a higher peak and slower return to baseline because fat adaptation temporarily downshifts rapid glucose disposal (“reverse metabolic inflexibility”) rather than proving true insulin resistance. Learn how to interpret trends despite interstitial‑fluid lag and ...

Blueprint stack review: What Bryan Johnson’s simplified longevity stack can and can’t do for men

Bryan Johnson’s commercial “Blueprint Stack” promises a simplified route into a longevity-focused routine. This blueprint stack review breaks down what’s actually in the stack as described, what the research says about the major components for men, and how to use a “stack” approach without drifting into expensive guesswork. “If a ‘stack’ helps you consistently hit ...

The hidden link between inflammation and heart disease: Why cholesterol is only half the story

Chronic arterial inflammation can turn LDL-based plaque dangerous by driving cytokine signaling (IL‑1β, IL‑6) that recruits macrophages and releases metalloproteinases to thin the fibrous cap until it ruptures, which helps explain why nearly 50% of heart attacks occur in men with “normal” cholesterol. A standard lipid panel won’t capture that risk, so this article breaks ...

Building muscle after 40: The science of getting stronger when recovery slows down

Men over 40 can still build muscle and strength, but anabolic resistance and slower tissue repair often extend recovery from heavy sessions to roughly 48–72 hours, meaning the hypertrophy stimulus has to be higher to meaningfully trigger muscle protein synthesis. Here’s how to adjust training volume and target 30–40 g of high‑quality protein (~3–4 g ...

Bulking vs cutting: The science of body recomposition for men

Bulking and cutting work by deliberately shifting energy balance: a 250–500 calorie daily surplus supports muscle protein synthesis and hypertrophy, while a sustained calorie deficit drives fat oxidation but can increase muscle protein breakdown. The key to body recomposition is committing to one clear signal for 12–16 weeks—rather than chasing muscle gain and leanness at ...

Best supplements for inflammation in men: What works, what’s safe, and how to choose

For most men, the best-supported supplement for reducing chronic, systemic inflammation is omega‑3 fish oil (EPA+DHA), which can shift eicosanoid signaling toward fewer pro‑inflammatory mediators and is typically studied at about 1–4 g/day taken with food. Here’s how to choose an evidence-based option (and dose) based on your main risk drivers and inflammation markers like ...

Testosterone and the Dietary Guidelines for Americans: What men should actually do

The phrase “testosterone dietary guidelines americans” sounds like a niche search query. But it reflects a real shift: more men are looking to federal nutrition guidance for answers about hormone health. The Dietary Guidelines for Americans (DGA) doesn’t set testosterone targets, but its focus on weight and cardiometabolic health overlaps with factors associated with testosterone ...

Brain fog in men: The best vitamins for brain fog and memory and the supplements that actually make sense

The most evidence-based vitamins for brain fog and memory in men are B12 (often alongside folate and B6) to correct deficiency and reduce homocysteine, plus vitamin D when status is low, because these pathways support brain energy metabolism, neurotransmitter function, and immune-driven inflammation control. Here’s how to tell when “brain fog” is a fixable signal ...

At what age does a man stop ejaculating? Understanding the changes in your body

There is no specific age when a man stops ejaculating, and many men can ejaculate throughout life, though semen volume and the “force” of ejaculation often decline with age.,[1] If ejaculation changes suddenly or stops completely, it is worth getting checked because the cause is often identifiable and treatable. “Most men don’t hit a birthday ...

Athlete biomarker testing for longevity: The lab numbers that keep men performing longer

For longevity-focused men who train, repeating key labs—especially HbA1c (a ~3‑month average of blood sugar) and ApoB (the number of atherogenic particles that can enter artery walls)—can reveal early metabolic drift and cardiovascular risk before performance drops or disease shows up. Pair those with iron, inflammation, and hormone/recovery markers to build a “healthspan dashboard” that ...

What muscles does cycling work? A physiologist’s guide to building power

Cycling primarily works the quadriceps, gluteus maximus, and hamstrings, while the core and hip–lower back stabilizers brace the pelvis to transfer force through a closed-kinetic-chain pedal stroke. If you only push down on the pedals you can leave “half your potential power” unused and increase knee load—here’s how biomechanics and bike fit help you recruit ...

Weights or cardio first? The evidence-based order that gets men results faster

For most men trying to build strength and muscle, do weights first and finish with cardio, because cardio-first increases fatigue and AMPK signaling (and can drain glycogen), which can reduce lifting volume and potentially blunt mTOR-driven hypertrophy. If endurance is your main goal or you’re splitting sessions across the week, the “best” order changes—here’s how ...

How long does it take to lose muscle? The science of detraining

Measurable muscle atrophy typically doesn’t begin until about 2–3 weeks of complete inactivity, with the first 5–7 days off usually reflecting depleted glycogen and water rather than lost contractile tissue. The real risk window—and why immobilization (bed rest or a cast) changes the timeline—comes down to how quickly protein synthesis drops when mechanical tension disappears. ...

Best push pull legs routine for muscle gain: How to run a push pull legs split without wrecking your joints

For most healthy men, a push pull legs split is one of the best push pull legs routines because it organizes training around movement patterns, distributes weekly volume efficiently, and builds in recovery so you can progress without living sore. The key is matching the split to your schedule, then using evidence-based volume, intensity, and ...

Worst foods for erectile dysfunction: How your diet affects your erection quality

Diets high in processed sugars, trans fats, and excessive sodium (a typical “Western diet”) can worsen erectile dysfunction by damaging the endothelium and reducing nitric oxide–driven vasodilation needed to fill and trap blood in the penis. Because penile arteries are smaller and show vascular injury earlier than the heart, your grocery list can affect erection ...

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Medical podcast

Listen to the latest episodes on men's health, hormones, performance, and longevity.

Episode 6: Honey packs for men: what they are, how long they last, and the hidden risks

February 10, 2026 · 10:01

Many honey-pack male enhancement sachets contain undeclared PDE5 inhibitors and can dangerously lower blood pressure.

Episode 5: The best multivitamin for men over 50: how to choose between popular brands like nature made and centrum

February 03, 2026 · 10:25

How to choose a multivitamin for men over 50 by matching formulas to diet, meds, and biology; Nature Made vs Centrum.

Episode 4: Are peptides legal? What the new FDA regulations mean for you

January 27, 2026 · 9:41

FDA restricted compounding of many peptides, placing 17 off-limits for human use and prioritizing evidence-based care.

Episode 3: Is Dave’s Killer Bread healthy or just hype?

January 23, 2026 · 10:39

An endocrinologist assesses whether Dave's Killer Bread's fiber and protein benefits outweigh added calories and sugars.

Episode 2: Your guide to effective testosterone replacement therapy near me

January 20, 2026 · 10:49

This episode guides diagnosing low testosterone, realistic TRT benefits, and finding safe, evidence-based local care.

Episode 1: Facing the truth: My experience with testosterone replacement therapy side effects

January 19, 2026 · 10:42

Evidence-based look at TRT side effects and the monitoring steps needed to manage them safely.

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Medical knowledge hub

Fertility & reproductive health

Navigate conception with clarity and science. Explore semen analysis, male infertility evaluations, and preparation for assisted reproduction like IVF and IUI. Learn how hCG, enclomiphene, and targeted supplements can improve sperm count, motility, and semen quality. Clear, evidence-based guidance to improve fertility and reproductive outcomes.

Fitness & physical performance

Train with your hormones, not against them. We cover strength, hypertrophy, VO2 max, recovery, and injury prevention through an endocrine lens. Discover how training, nutrition, and daily activity can impact testosterone levels and support natural balance. Use estradiol balance for joint health, plan sleep taper cycles before competitions, and turn smart physiology into new PRs.

Lifestyle & longevity

Design daily habits that support hormonal balance and long-term vitality. Master sleep and circadian timing, eat for metabolic stability, and use micronutrients with purpose. Make informed choices about alcohol, nicotine, sauna, and cold exposure. We translate longevity research into clear, practical playbooks you can apply today.

Mental health

Everything you need to know about how hormones shape mood, focus, and emotional balance. We explore anxiety, depression, ADHD, stress response, and cognitive performance through the lens of neuroscience and endocrinology. Learn how to stabilize cortisol, support healthy testosterone levels, and rebuild mental clarity.

Sexual health

Start with what matters: desire, function, and comfort. We explain libido, arousal, erectile function, orgasm, and sexual pain, and how medicines and hormones influence them. Clear language, evidence-based guidance, and practical steps to understand your body and improve sexual well-being.

Testosterone 101

Everything you need to know about testosterone, backed by the latest research. We turn complex topics like diagnosis, dosing, delivery methods, and lab results into simple, practical insights. Understand TRT benefits and risks, maintain estradiol balance, and spot drug interactions - all grounded in evidence, not hype.

Authors and medical reviewers

Dr. Alexander Grant, MD, PhD: Urologist & Men's Health Advocate

Dr. Alexander Grant is a urologist and researcher specializing in men's reproductive health and hormone balance. He helps men with testosterone optimization, prostate care, fertility, and sexual health through clear, judgment-free guidance. His approach is practical and evidence-based, built for conversations that many men find difficult to start.

Dr. Bruno Rodriguez, DPT, CSCS: Strength, Recovery, and Physical Therapy Expert

Dr. Bruno Rodriguez designs strength and recovery programs for professional athletes and patients recovering from surgery. He focuses on building strength, mobility, and effective recovery while lowering injury risk. His goal is for men to achieve the best performance in the gym and in daily life.

Dr. Jonathan Pierce, PhD: Clinical Psychologist & Neuroscience Specialist

Dr. Jonathan Pierce integrates clinical psychology with neuroscience to connect mood, motivation, and hormones. He helps men manage stress, low drive, and anxiety, then builds durable habits for focus, resilience, and performance at work and at home.

Dr. Susan Carter, MD: Endocrinologist & Longevity Expert

Dr. Susan Carter is an endocrinologist and longevity expert specializing in hormone balance, metabolism, and the aging process. She links low testosterone with thyroid and cortisol patterns and turns lab data into clear next steps. Patients appreciate her straightforward approach, preventive mindset, and calm, data-driven care.