The Longevity Dictionary
Health terms explained like I would explain them to a friend over coffee. No medical word salad. No scare tactics. Just what it means, why it matters, what range is generally considered healthy, and what may help.
Newsletter links can point right to a term, like /longevity-dictionary/#apob
Blood Markers Explained
These are the numbers that show up on blood work and usually make normal people say, “Okay, but what does that mean?”
ApoB
Heart HealthExplain It Simply
Think of ApoB like the number of delivery trucks carrying cholesterol through your arteries. More trucks means more chances for traffic jams, scratches, and buildup.
Why Should You Care?
Too many ApoB particles may raise long-term heart risk, even if you feel perfectly fine today.
General Healthy Range
Many people aim for under 90 mg/dL. If someone is higher risk, a doctor may want it lower.
What May Help?
- Better body composition
- Walking and Zone 2 cardio
- Strength training
- Better sleep
- Better food quality
- Talking with your doctor
LDL Cholesterol
Heart HealthExplain It Simply
LDL is like cargo being carried through the bloodstream. The body needs some cargo, but too much can become a problem over time.
Why Should You Care?
High LDL can be part of a pattern that raises the chance of plaque buildup in the arteries.
General Healthy Range
Common lab goal is under 100 mg/dL. Lower goals may be used for people with higher heart risk.
What May Help?
- Better body fat levels
- More activity
- Better sleep
- Less ultra-processed food
- Medical guidance when needed
HDL Cholesterol
Heart HealthExplain It Simply
Think of HDL like part of the cleanup crew. It helps move cholesterol through the system in a healthier direction.
Why Should You Care?
Low HDL can be one sign that your metabolic health or activity level needs attention.
General Healthy Range
For men, 40 mg/dL or higher is commonly considered acceptable. Higher is often better, but context matters.
What May Help?
- Regular movement
- Strength training
- Fat loss if needed
- Not smoking
- Better metabolic health
Triglycerides
Metabolic HealthExplain It Simply
Think of triglycerides like leftover fuel floating around after your body has more energy than it needs.
Why Should You Care?
High triglycerides can point to metabolic strain, especially when paired with low HDL or higher blood sugar.
General Healthy Range
Under 150 mg/dL is commonly considered normal. Many longevity-minded people like seeing it closer to 100 or below.
What May Help?
- Walking after meals
- Less sugar and refined carbs
- Fat loss if needed
- Better sleep
- Consistent exercise
HbA1c
Blood SugarExplain It Simply
HbA1c is your 90-day blood sugar report card. One bad meal will not ruin it, but repeated blood sugar spikes can push it higher.
Why Should You Care?
Higher A1C may mean your body is struggling to keep blood sugar under control.
General Healthy Range
Below 5.7% is commonly considered normal. Many people like seeing it closer to the low-to-mid 5s.
What May Help?
- Walking after meals
- Strength training
- Better sleep
- Protein-first meals
- Less ultra-processed food
Ferritin
Iron / InflammationExplain It Simply
Ferritin is like your body’s iron storage tank. If it is high, the tank may be too full, or it may be flashing a warning light because something else is going on.
Why Should You Care?
Too much stored iron may create oxidative stress, but high ferritin can also come from inflammation, liver issues, infection, alcohol, or metabolic problems.
General Healthy Range
Ranges vary a lot by lab, sex, and situation. Many labs list adult male ranges roughly around 30 to 400 ng/mL.
What May Help?
- Getting follow-up labs
- Checking iron saturation
- Reviewing alcohol intake
- Looking at liver markers
- Talking with your doctor
Testosterone
HormonesExplain It Simply
Testosterone is like part of your internal drive system. It helps support energy, muscle, motivation, confidence, libido, and recovery.
Why Should You Care?
Low testosterone can make life feel like you are driving with the parking brake on.
General Healthy Range
Many labs use a wide range around 300 to 1,000 ng/dL for adult men. Symptoms and free testosterone matter too.
What May Help?
- Strength training
- Better sleep
- Healthy body fat
- Enough protein
- Managing stress
- Medical evaluation when low
Free Testosterone
HormonesExplain It Simply
Total testosterone is like money in the bank. Free testosterone is like cash in your pocket that you can actually spend.
Why Should You Care?
You can have decent total testosterone but still feel off if less of it is available to your body.
General Healthy Range
Free testosterone ranges vary a lot by lab method. Always compare your number to the lab’s range and symptoms.
What May Help?
- Reviewing SHBG
- Improving sleep
- Managing stress
- Strength training
- Talking with a hormone-aware clinician
Cortisol
StressExplain It Simply
Cortisol is like your body’s built-in alarm system. You need it, but you do not want the alarm blasting all day.
Why Should You Care?
Too much or poorly timed cortisol may affect sleep, belly fat, mood, blood sugar, and recovery.
General Healthy Range
Morning cortisol ranges vary by lab and time collected. Timing matters a lot, so use your lab’s reference range.
What May Help?
- Morning sunlight
- Consistent sleep schedule
- Walking
- Breathing or relaxation
- Reducing late-night stress
Wearable & Daily Health Terms
These are the numbers your watch, ring, or fitness tracker may show you. Helpful, but don’t let them make you crazy.
Deep Sleep
SleepExplain It Simply
Total sleep is time in bed. Deep sleep is when the repair crew shows up.
Why Should You Care?
Low deep sleep may affect recovery, memory, hormones, soreness, and how sharp you feel the next day.
General Healthy Range
Many adults spend about 10% to 20% of sleep in deep sleep. Wearables estimate this, so watch trends more than one night.
What May Help?
- Finish eating earlier
- Cool bedroom
- No late caffeine
- Consistent bedtime
- Limit alcohol
HRV
RecoveryExplain It Simply
HRV is like checking how well your body shifts gears. A flexible body can move between stress and recovery more easily.
Why Should You Care?
Low HRV can show up when you are stressed, sick, under-recovered, sleeping poorly, or overtraining.
General Healthy Range
HRV varies wildly by person and device. Your personal trend matters more than comparing yourself to someone else.
What May Help?
- Better sleep
- Rest days
- Walking
- Breathwork
- Less alcohol
- Managing stress
Resting Heart Rate
Heart EfficiencyExplain It Simply
A lower resting heart rate can mean your heart is doing its job with fewer beats, like an efficient engine.
Why Should You Care?
A rising resting heart rate may signal poor recovery, stress, illness, dehydration, or declining fitness.
General Healthy Range
A common adult resting range is 60 to 100 bpm, but fit people may run lower. Symptoms matter.
What May Help?
- Zone 2 cardio
- Walking
- Better sleep
- Hydration
- Recovery days
Sleep Efficiency
SleepExplain It Simply
If you spend 8 hours in bed but only sleep 6.5, your sleep efficiency is not great. It is the difference between being in bed and actually sleeping.
Why Should You Care?
Low sleep efficiency can leave you tired even if you technically went to bed early.
General Healthy Range
Many sleep experts consider 85% or higher a decent target. Your trend matters most.
What May Help?
- Regular sleep schedule
- Cool dark room
- Limit late liquids
- Earlier last meal
- Wind-down routine