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In 33 studies, keto didn't cost muscle or strength, and steady cardio recovered once people adapted. Sprints, intervals and race pace are where it costs you.

Why LDL cholesterol rises a lot on keto in some people and barely moves in others: what trials show about body weight, apoB, saturated fat and blood tests.

What keto flu is, how long it lasts, and what sodium, potassium and magnesium can and can't do, with the EU's safe sodium intake of 2 g a day for scale.

How keto works, how many carbs it allows, how long ketosis takes and what the first week feels like, from 14 cited sources. Plus who should see a doctor first.

Blood sugar spikes after eating if you don't have diabetes: what's normal on a glucose monitor, why dips can make you hungry, and how walking breaks help.

How to improve gut health, from 6 cited studies: how much fibre, why plant variety and fermented foods matter, and what probiotics can and can't do.

What breaks a fast, whether 16:8 or longer fasts need electrolytes, and how much sodium is sensible, from expert fasting definitions and 6 cited sources.

Lift weights, eat more protein, lose about 0.5–1% of your weight a week and protect your sleep: what trials show about losing fat while keeping muscle.

VO2 max by age from 7,783 lab tests, why higher fitness goes with a longer life, and how to raise it: what 28 trials of intervals and steady cardio found.

About 10 or more hard sets per muscle a week builds muscle, and trained lifters did best on 12–20. What the research says about volume, failure and frequency.

The best room temperature for sleep, from 7 cited studies: why heat disturbs sleep more than cold, tips for hot summer nights, and who should see a doctor.

Does magnesium help you sleep? What trials of glycinate, citrate, oxide and threonate found, the EU's 250 mg a day limit, and who should ask a doctor first.

What morning sunlight does to your body clock, sleep and alertness, how bright and how long the studies used, and why a window is not the same as going outside.

An ice bath after every lifting session meant less muscle growth in 8 trials. After cardio it changed nothing. What a sauna does, and how long each should last.

No study shows you can reset dopamine, but breaks from your phone have been tested: what a 467-person trial and a review of 21 studies found, and how to try it.

How to do the physiological sigh (cyclic sighing), what a month-long trial of 108 adults found, how it compares with box breathing, and who should be careful.

Spaced repetition schedule for exams: how long to wait between reviews, why to test yourself each time, and why it beats cramming. From 7 cited sources.

How much omega-3 per day: the 250–500 mg of EPA and DHA advised for adults, what 1 g capsules did in big trials, and why more isn't always better.

How much caffeine to take before a workout, how long before, and how late is too late for sleep: doses per kg of body weight, from 7 cited reviews and trials.

How many grams of creatine a day, whether to load, the best time to take it, and what research says about women, over-40s, hair loss and kidneys.

Biohacking for beginners: which habits and supplements have good evidence, which don't yet, and how to stay safe with supplements, from 7 cited sources.