The science of your own body — what to eat, how to sleep, how exercise actually works, and what the evidence says about living well and living long.
No fad diets. No supplements. Just the evidence-backed basics that 90% of nutrition science agrees on.
A 2019 NIH randomized controlled trial found that people given ultra-processed food diets spontaneously ate 500 more calories per day and gained 2 lbs. Those given unprocessed diets lost weight — eating the same macros. The processing itself — not the macros — appears to drive overconsumption. Eat real food. Mostly plants. Not too much. (Michael Pollan's 7-word advice still holds.)
Your brain runs almost exclusively on glucose (from carbs). Not all carbs are equal: complex carbs (whole grains, vegetables, legumes) digest slowly, causing gentle blood sugar rises. Simple carbs (sugar, white flour) spike blood sugar and crash it — causing hunger cycles.
Essential for muscle repair, enzyme production, hormone synthesis, and immune function. Most adults need ~0.8g per kg of body weight (athletes: 1.2–2.0g/kg). Protein is the most satiating macronutrient — high-protein meals keep you fuller longer, reducing overall calorie intake.
Fat was demonized from the 1970s–1990s (wrongly). Fat is essential for hormone production, brain function (60% of brain is fat), vitamin absorption (A, D, E, K), and cell membrane structure. Unsaturated fats (olive oil, nuts, avocado) are beneficial. Trans fats (partially hydrogenated oils) are genuinely harmful.
Average American consumes 17 teaspoons of added sugar per day (WHO recommends max 6). Excess sugar spikes insulin, promotes fat storage, drives inflammation, and is strongly linked to type 2 diabetes, obesity, and cardiovascular disease. Liquid sugar (soda, juice) is particularly harmful — doesn't trigger fullness signals.
Your kidneys need minimum ~1L of water daily just to function. Mild dehydration (1–2% of body weight) reduces cognitive performance by 10–20%. Coffee and tea count toward hydration. Urine color is your best indicator: pale yellow = good, dark yellow = drink more.
Most people get 10–15g of fiber daily; recommended is 25–38g. Fiber feeds gut bacteria, slows glucose absorption, lowers cholesterol, and is the strongest dietary predictor of longevity in studies. Source: vegetables, legumes, whole grains, fruits.
Essential fatty acids your body can't make — you must eat them. Found in fatty fish (salmon, mackerel, sardines), walnuts, and flaxseed. Linked to reduced inflammation, improved heart health, brain function, and mood. Most Westerners are deficient.
Half your plate: vegetables and fruits. One quarter: protein. One quarter: whole grains. This simple framework, without calorie counting, aligns with virtually every healthy dietary pattern studied (Mediterranean, Japanese, Nordic).
Matthew Walker's "Why We Sleep" called sleep "the single most effective thing we can do to reset our brain and body health each day." The science backs this up completely.
Your brain is incredibly active during sleep — doing things impossible while awake.
Sleep occurs in 90-minute cycles, each containing stages:
Transition to sleep. Body temperature drops, heart rate slows. Sleep spindles (bursts of brain activity) in N2 are linked to motor learning — why you remember new skills better after sleep.
Most restorative stage. Growth hormone released. Glymphatic system flushes brain of toxic waste including amyloid plaques linked to Alzheimer's. Memory consolidation from hippocampus to cortex. Dominates early-night sleep.
Dream stage. Brain nearly as active as waking. Emotional memory processing — REM strips emotional charge from difficult memories while preserving the information. Dominates late-night/morning sleep. Cutting sleep short eliminates REM disproportionately.
Alcohol helps you fall asleep but destroys sleep quality. It sedates you (different from natural sleep), dramatically suppresses REM sleep, and fragments sleep in the second half of the night. Even moderate alcohol before bed reduces sleep quality by 24%.
What actually works, what doesn't, and why.
Go to bed and wake up at the same time daily — including weekends. Your circadian rhythm is a biological clock; irregular schedules cause "social jetlag" with measurable health effects.
Your body must lower core temperature by ~2°F to initiate sleep. A cool room helps. Hot baths before bed paradoxically help by pulling heat to the skin surface and cooling the core.
Blue light from screens suppresses melatonin by 50% for 3 hours. Your brain interprets it as daylight and delays sleep onset. Night mode/orange glasses help but don't eliminate the problem.
Sets your circadian clock. Natural light (even cloudy) is 10–50x more powerful than indoor lighting for calibrating your internal clock. Links morning waking to evening sleepiness reliably.
Caffeine has a ~6-hour half-life. A coffee at 3 PM = half a coffee's worth of stimulation at 9 PM. Caffeine blocks adenosine (the brain's sleep pressure signal) — so you feel less sleepy but adenosine keeps building. When caffeine wears off: you crash hard.
Exercise is medicine. 150 minutes of moderate activity per week reduces all-cause mortality by 35% — more than any drug ever tested.
Activities: running, cycling, swimming, brisk walking. Benefits: heart efficiency (larger stroke volume), lung capacity, mitochondria density, BDNF production (brain-derived neurotrophic factor — literally grows new brain cells). Target: 150 min/week moderate or 75 min/week vigorous.
Activities: weights, bodyweight exercises, resistance bands. Benefits: muscle mass (which burns 3x more calories than fat at rest), bone density, insulin sensitivity, posture, injury prevention, and hormonal health. Recommended: 2–3 sessions per week. Most important form of exercise as you age (sarcopenia = age-related muscle loss).
Activities: yoga, stretching, Pilates. Benefits: range of motion, injury prevention, posture. Often neglected. Static stretching after exercise (not before — before, use dynamic warmup). Tight hip flexors from sitting are linked to back pain in desk workers.
A meta-analysis of 49 studies found exercise as effective as antidepressants for mild-to-moderate depression. Mechanism: aerobic exercise releases BDNF (grows hippocampus), endorphins, serotonin, and dopamine. 30 minutes of moderate exercise reduces cortisol (stress hormone) for hours afterward.
After intense exercise, your body burns extra calories for up to 24–48 hours (excess post-exercise oxygen consumption). High-intensity interval training (HIIT) produces the strongest EPOC — 20 minutes of HIIT can burn calories equivalent to 40 minutes of steady cardio when total effect is counted.
Prolonged sitting (8+ hours/day) is independently associated with increased mortality risk even in people who exercise regularly. Standing desks, walking meetings, and breaks every 30–45 minutes partially offset this. The goal: reduce continuous sitting, not just total sitting.
38 trillion bacteria live in your gut — outnumbering your own cells. They're not passengers: they shape your immune system, mood, metabolism, and more.
Your gut and brain are connected via the vagus nerve. 90% of serotonin (the "happiness" neurotransmitter) is produced in your gut, not your brain. Gut bacteria influence serotonin production — explaining the emerging link between gut health and depression/anxiety.
70% of your immune system lives in your gut (gut-associated lymphoid tissue). A healthy microbiome teaches your immune system to distinguish friend from foe, pathogens from food. Dysbiosis (imbalanced microbiome) is linked to autoimmune diseases, allergies, and inflammatory conditions.
Prebiotic foods (what bacteria eat): garlic, onion, leeks, asparagus, bananas, oats, apple. Probiotic foods (bacteria themselves): yogurt, kefir, kimchi, sauerkraut, miso, tempeh. Diversity of plant foods = diversity of bacteria = healthier microbiome. Aim for 30+ different plant foods per week.
Antibiotics (necessary when needed, but wipe out beneficial bacteria too — take probiotics during/after courses). Ultra-processed foods. Chronic stress. Lack of sleep. Artificial sweeteners (emerging evidence of microbiome disruption). Low-fiber diets.