Six questions this community actually asks — answered with evidence tiers, not opinions

Long easy sessions where you can still hold a conversation, plus a small dose of genuinely hard intervals, is the most reliably proven way to build more and better mitochondria. It is free, and nothing on this list beats it.

Watch: The mistake is doing everything at a medium effort — too hard to accumulate volume, too easy to drive adaptation.

Repair and clearance run overnight. Chronic short sleep raises inflammation and blunts glucose handling within days — measurable in the same markers this lens reads.

Watch: If sleep is short, fix that before buying anything.

CoQ10 physically carries electrons inside the energy chain and doubles as an antioxidant there. Your own levels fall with age, and statins lower them further by blocking the same pathway that makes cholesterol.

The nuance: Ubiquinol is the reduced form and absorbs several times better than plain ubiquinone in adults, which is real. The stronger claim — that conversion 'stops working' at 40 — is overstated; the decline is gradual and matters more with each decade. If you're older, on a statin, or paying for it anyway, the better-absorbed form is the sensible default.

Watch: Take it with fat — it's fat-soluble, and a dry capsule on an empty stomach is largely wasted.

The most evidence-backed supplement in this whole space. It recharges the fast energy system used for hard efforts, and there's decent evidence for cognitive benefit under sleep deprivation.

The nuance: Worth being precise: creatine feeds the phosphocreatine system, it does not build mitochondria. It's on this list because it's the cheapest real win in the category, not because it's mitochondrial.

NAD+ is the shuttle that carries electrons into the energy chain, and it falls with age. Supplementing the precursors does raise blood NAD+ measurably.

The nuance: The gap worth knowing: raising the number is well demonstrated; translating that into how people actually feel or perform has been inconsistent across human trials. You are buying a plausible mechanism, not a proven outcome.

Triggers mitophagy — the cleanup process that clears worn-out mitochondria so better ones replace them. Your gut makes it from pomegranate and walnut compounds, but only some people's gut bacteria can, which is why supplementing is the reliable route.

The nuance: One of the few compounds here with genuine placebo-controlled human trials, showing improvements in muscle endurance and, more recently, markers of immune ageing in midlife adults. Still modest effects, and no evidence it extends anyone's life.

At low doses it acts as an electron shuttle, picking up electrons and handing them further down the chain — effectively routing around a congested step. That's a real, well-described mechanism.

The nuance: The dose response is a U: low supports, high does the opposite and becomes pro-oxidant. Human data for everyday cognitive or energy use is thin, and the product quality question is serious — this is a dye, and non-pharmaceutical grades carry contaminants you do not want.

A short peptide your own mitochondria encode and release during exercise — a genuine internal signal that improves glucose uptake and fat burning, working through the same energy sensor exercise activates. Your natural levels fall with age.

The nuance: That it exists and rises with exercise in humans is established. That injecting it produces those benefits is not — the therapeutic evidence is animal work. It is also a prohibited substance in tested sport.

A small molecule that switches on the same gene programme endurance exercise switches on, which is why it gets called an exercise mimetic. In sedentary mice it improved endurance and mitochondrial density without training.

The nuance: Be clear-eyed: there have been no human trials at all. Everything known is from rodents, it is approved by no regulator anywhere, and it is sold as a research chemical with no purity guarantee. This is the least-evidenced item on this list and often the most-hyped.

Glutathione is your main internal antioxidant. NAC supplies the scarce ingredient your body needs to make more of it, and it does reliably raise glutathione and lower oxidative-stress markers.

The nuance: The catch nobody mentions: the oxidative signal from training is part of what tells your body to adapt. Taken in high doses right around sessions, general antioxidants have repeatedly blunted the training response. Same dose, different hour, different outcome — keep the training window clean and take buffers well away from it.

Classic antioxidants, and the ones with the clearest evidence of a downside when mistimed.

The nuance: Multiple human trials show high daily doses taken around training reduce the gains in mitochondrial and endurance adaptation. Food-level intake is fine; it's the gram-scale doses stacked on top of a training block that backfire.

Antioxidants that concentrate in or near the mitochondrion rather than mopping up indiscriminately.

The nuance: The theory is that targeted beats blanket — you protect the machinery without deleting the whole training signal. Early human work is interesting but nowhere near settled.

The boring answer, and usually the right one. Energy production needs raw materials, and a shortfall in any of them produces exactly the fatigue people go looking for exotic fixes for.

Watch: If you feel flat and haven't measured ferritin, B12, folate, vitamin D and a full thyroid panel, that is the cheapest possible next test — and far more likely to explain it than anything injectable.

Consistency of timing predicts health outcomes at least as strongly as total hours. A fixed wake time — including weekends — is the single highest-leverage change most people can make.

Bright light early anchors your body clock; bright light late pushes it back and delays melatonin. This is the mechanism, not a wellness slogan.

Core temperature has to drop for deep sleep to consolidate. A room that's too warm fragments the deep sleep you're trying to protect.

It puts you to sleep and then wrecks the second half of the night — suppressed REM, more waking, higher heart rate. It is the most reliable way to make a tracker look bad.

Caffeine's half-life is around five to six hours, so an afternoon coffee is still meaningfully present at bedtime. It reduces deep sleep even when you fall asleep fine.

Watch: Pre-workout taken for an evening session is the usual hidden culprit.

Involved in hundreds of reactions including the ones that calm the nervous system. Well-absorbed forms like glycinate are commonly used at night.

The nuance: Evidence for better sleep is modest and strongest in people who were low to begin with. Cheap, low-risk, not a fix for a bad schedule.

A timing signal more than a sedative — most useful for shifting a body clock, as with travel or shift work.

The nuance: Common doses are far higher than needed; small amounts taken earlier in the evening usually beat a large dose at bedtime. It's also a potent antioxidant inside mitochondria, which is why it shows up in both of these lenses.

Loud snoring, witnessed pauses, morning headaches or heavy daytime sleepiness deserve a real test rather than a supplement.

The nuance: Especially relevant here: apnoea and testosterone therapy each make the other worse, and untreated apnoea will keep pushing hematocrit up no matter what else you change.

Compounds differ enormously in how much they convert to DHT-type androgens in skin. Two protocols at the same total dose can produce completely different skin.

Watch: If skin flared within weeks of a change, the change is the lead suspect. Your events timeline and protocol history make that a checkable question rather than a guess.

High-glycaemic eating raises insulin, which raises IGF-1 signalling, which raises oil production and androgen sensitivity together.

The nuance: Low-glycaemic-load diets have improved acne in controlled trials. This is one of the few dietary claims in skin that actually held up.

Milk — skim especially — is repeatedly associated with acne through the same IGF-1 pathway, and whey protein flares have been documented specifically in lifters.

The nuance: Association, not proof, and it clearly doesn't apply to everyone. But if you're drinking two whey shakes a day and fighting your back, it is a cheap four-week experiment.

Aggressively suppressing estradiol to manage other side effects tends to worsen skin, along with joints, mood and libido.

The nuance: Balance beats suppression. This is a dosing conversation with a prescriber, not a solo experiment.

Benzoyl peroxide and topical retinoids have decades of evidence for exactly this kind of acne, and are usually the first thing a doctor reaches for.

Watch: Body acne responds better when treatment covers the whole area rather than individual spots.

Deep, painful nodules that scar are worth seeing a doctor about early rather than after the scarring. Scars are permanent in a way the acne isn't.

The nuance: Systemic options exist and work well, but they carry real monitoring requirements — including liver and lipids, both of which this app is already tracking for you.

Showering promptly after training and not sitting in a soaked shirt helps at the margin.

The nuance: Worth saying plainly: this is a small lever. Hormonal acne is not caused by being dirty, and scrubbing harder makes it worse, not better.

The single best-evidenced lever in this entire lens. Fiber feeds the bacteria that produce butyrate, the short-chain fatty acid your colon cells use as their main fuel — you are literally feeding the lining. Variety of plants matters as much as total grams.

Watch: Increase it gradually. Going from very low to very high fiber in a week produces exactly the bloating people then blame on the food itself.

Absorption isn't unlimited per sitting for the purposes of muscle building, which is the real argument for spreading protein across the day rather than one enormous meal.

The nuance: The 'you can only absorb 30g' line is wrong as stated — you absorb nearly all of it. What plateaus is the muscle-building response, which is a different claim.

Slowing stomach emptying is not a side effect of these drugs, it's a main mechanism — it's part of why you feel full. Nausea, constipation and reflux follow directly from that.

Watch: The real risk is quiet: appetite suppression makes it easy to undereat protein and fiber badly while losing weight fast, which costs muscle. Track protein deliberately rather than by feel here.

Anything swallowed hits the liver before the rest of you. Oral 17-alpha-alkylated compounds are specifically designed to survive that pass, which is exactly why they're harder on the liver than injectables.

Watch: If ALT and GGT are drifting up on an oral, that's the mechanism working as designed, not a surprise.

Ibuprofen and naproxen reduce the prostaglandins that protect the stomach and gut lining. Routine use around training — common in this population — measurably increases gut permeability and bleeding risk.

Watch: Occasional use for an injury is a different thing from taking them before every session.

Directly increases intestinal permeability and is one of the most reliable ways to raise GGT. It's also the lever people most consistently leave out when listing what they're taking.

Live bacteria taken to shift the gut community. Some specific strains have real trial evidence for specific conditions — antibiotic-associated diarrhoea most clearly.

The nuance: The honest version: benefits are strain-specific and don't generalise, most products don't name the strain precisely enough to match any trial, and colonisation is usually temporary. A generic multi-strain capsule is closer to a lottery ticket than a treatment.

The preferred fuel of the cells lining the small intestine, which is why it's marketed for gut repair.

The nuance: The mechanism is genuine and it has real evidence in clinical settings — critical illness, burns. Extending that to a healthy lifter with an unremarkable gut is a leap the data doesn't currently support.

Supplemental enzymes to help break food down.

The nuance: Genuinely necessary in diagnosed pancreatic insufficiency, and that's a real diagnosis worth having if symptoms fit. In people without it, the evidence that they improve digestion or absorption is thin.

Coeliac disease, inflammatory bowel disease, H. pylori and pancreatic insufficiency are all real, common, testable, and treatable — and all get mistaken for 'a sensitive stomach' for years.

Watch: Blood in stool, unexplained weight loss, persistent night-time symptoms or new anaemia are not supplement problems. Those go to a doctor.

Loading a painful tendon deliberately — slowly, heavily, under control — has the best human evidence of any treatment for tendinopathy. Rest alone reliably underperforms it.

Watch: It's normal for a rehabilitating tendon to be mildly sore during the work. Sharp pain, or pain that's worse the next morning, means the dose was too high.

The muscle-versus-tendon gap is a timing problem, so the fix is a timing one: add load at a rate the slow tissue can follow, especially in the first months of a strength jump.

Watch: This is the lever that matters most on androgens and matters least when nothing is accelerating strength.

Collagen peptides taken about an hour before loading, with vitamin C, are the most-studied nutritional lever here — the idea being to supply building blocks while circulation to the tendon is briefly raised.

The nuance: Evidence is genuinely mixed. Some trials show improved collagen synthesis markers and pain, others show nothing beyond the protein itself. It's cheap and low-risk, which is a fair reason to try it — not the same as it being proven.

Oestrogen supports collagen, joint lubrication and tissue comfort. Aggressive aromatase-inhibitor use to chase a low number is one of the most common self-inflicted causes of joint pain in this community.

Watch: Dry, achy, creaky joints appearing shortly after starting or raising an AI is the pattern. That's information, and it points at the dose.

Peptides very widely used in this community specifically for tendon and ligament complaints, based on animal work showing accelerated healing of tendon, ligament and gut tissue.

The nuance: Be clear-eyed about the gap: the animal data is real and reasonably consistent, and the human data essentially does not exist — no completed controlled trials for these indications. They're sold as research chemicals with no purity guarantee, and both are prohibited in tested sport. The confidence with which they're recommended online is not backed by human evidence.

Raise IGF-1, which is genuinely involved in collagen synthesis — the plausible kernel behind the reputation for helping connective tissue.

The nuance: What's missing is outcome data: that IGF-1 rises is easy to show; that tendons heal faster or tear less as a result is not established in humans. Carpal-tunnel-type symptoms from fluid retention are a recognised side effect at higher doses.

Modest anti-inflammatory effect with reasonable evidence for joint stiffness in inflammatory arthritis.

The nuance: Extending it to mechanical tendon pain in a healthy lifter is less supported. Reasonable general-health purchase; not a tendon treatment.

They reliably reduce pain in the short term, which is genuinely useful when pain is stopping you loading at all.

The nuance: The trade-off worth knowing: tendinopathy is largely a degenerative rather than inflammatory problem, and there's reasonable evidence that blunting the inflammatory signal around training interferes with tendon and muscle adaptation. Useful short-term tool, poor long-term strategy — and see the gut lens for the other cost.

Worth knowing because it's specific and serious: ciprofloxacin and related antibiotics carry a documented risk of tendon damage and rupture, highest in the Achilles, and the risk persists for weeks after the course.

Watch: If you've recently taken one and a tendon starts complaining, that's a real association and a reason to back off load and speak to a doctor — not a coincidence.

Nothing else on this list comes close. Sleep restriction degrades attention, working memory, emotional regulation and impulse control within days, and the person affected is famously bad at noticing it.

One of the best-evidenced interventions for depressive symptoms that exists, with effect sizes competitive with first-line treatments in mild-to-moderate cases. It's free and you're likely already doing some.

Over-suppressing oestrogen on an aromatase inhibitor reliably produces flat mood, no libido, poor sleep and aching joints — the exact cluster people then attribute to needing more testosterone.

Watch: If mood dropped after starting or raising an AI, that timing is the finding. Take it to whoever prescribes it before adding anything.

The same cheap supplement from the energy lens has accumulating evidence for cognitive benefit specifically under stress — sleep deprivation being the clearest case.

The nuance: Effects in well-rested people are small to absent. It's most useful exactly when you're most depleted, which is a genuinely useful property rather than a hedge.

EPA-dominant formulations have reasonable trial evidence as an add-on for depressive symptoms, and the brain is structurally dependent on these fats.

The nuance: Add-on is the operative word — the evidence is much better alongside treatment than instead of it.

Genuinely improves alertness and reaction time, and tolerance builds fast, so much of the daily effect in habitual users is restoring baseline rather than exceeding it.

Watch: See the sleep lens: the afternoon dose that fixes today's fog is often what's causing tomorrow's.

Widely used off-label for focus. Modafinil has real evidence for wakefulness in diagnosed sleep disorders; the racetam family is mostly old, small or non-Western trial data.

The nuance: Two honest caveats: benefits in healthy, well-rested people are much smaller than the marketing implies and sometimes absent, and 'stimulant that lets you sleep less' is a way of borrowing against the largest lever on this list.

One of the better-studied herbal options, with several trials showing reduced anxiety and lower cortisol.

The nuance: Trials are mostly short and small. There are also documented cases of liver injury, which is rare but real and under-mentioned — and it can suppress thyroid symptoms' visibility by nudging thyroid hormones.

Starting, stopping and cycling androgens all move mood, and coming off is the well-recognised risk window — low mood after cessation is common, documented, and usually temporary.

Watch: Knowing that in advance is protective. Planning a taper with a prescriber, rather than stopping abruptly, is the difference between a rough few weeks and a crisis.

If low mood has lasted more than a couple of weeks, or you've lost interest in things you normally care about, that's a clinical picture with genuinely effective treatments — not an optimisation problem.

Watch: This is the one item on any list in this app where the right move is a person, not a protocol. If you're having thoughts of harming yourself, contact a crisis line or emergency services now.