My health check is coming up again. What should I change?

Before a repeat health check, first follow what your doctor or the clinic told you, including how long to fast. Some tests also need you to avoid overeating, alcohol, smoking or hard exercise the day before, so ask what yours need, and get a good night's sleep. Keep taking your regular medicines unless your doctor tells you otherwise. In the months before, the thing to do is keep everyday habits in eating, activity, sleep and alcohol as part of normal life; you do not need to change them just for the test. Ask the doctor to explain your results on the day.

What should I do the day before and the morning of a health check?

Most of the preparation happens in the last 24 hours. MedlinePlus, the health information service of the US National Library of Medicine, says the first step for any lab test is to follow all the instructions your provider gives you.

Follow the fasting instructions

MedlinePlus explains that fasting means not eating or drinking anything except water for up to several hours or overnight, because nutrients from food are still in the bloodstream for a while and can change the results of some blood tests. The length varies, so ask the clinic how long you need. Cleveland Clinic says it is typically 10 to 12 hours, which is why many people book a morning appointment and fast overnight.

Cleveland Clinic advises plain water only, and says coffee makes you urinate more, which can affect some results. Have your coffee after the test.

The day before

MedlinePlus says that for some lab tests you may need preparations such as:

• not overeating the day before
• avoiding alcohol
• not smoking
• avoiding strenuous exercise

Ask the clinic which of these apply to your tests. If any do, a large birthday dinner, an evening at a bar or a hard gym session the night before are all worth moving to another day. A normal, moderate dinner and a gentle walk are fine.

Sleep the night before

The US CDC recommends 7 hours or more of sleep for adults aged 18 to 60. It suggests going to bed and getting up at the same time, turning off devices at least 30 minutes before bed, and avoiding large meals and alcohol before bedtime. If the appointment is early, go to bed earlier rather than cutting your sleep short.

Should I stop my regular medicines before the check?

No, not on your own. MedlinePlus advises not stopping any medicine unless your provider tells you to. Cleveland Clinic says you can usually take your regular prescription and over-the-counter medicines before a fasting blood test unless your doctor advises otherwise.

Tell the clinic what you take

MedlinePlus advises telling your provider about every medicine, vitamin and supplement you take, including those bought without a prescription, because some can affect certain results. Write a list with the name and how often you take each one, or take photos of the packets.

If the clinic gives special instructions

Some tests need different preparation, such as avoiding certain foods or medicines for a set time. MedlinePlus advises making sure you understand the instructions before the day of the test, and asking your provider if anything is unclear.

What everyday habits do general guides suggest for adults?

If your doctor gave you specific advice at the last check, follow that first. Beyond that, the general guides below apply to most adults. They are habits for normal life, not a way to prepare for one test.

Eating

Thailand's food-based dietary guidelines include eating food from all 5 food groups, eating rice as the main staple, eating fish, eggs, lean meat and dried beans, eating vegetables and fruit regularly, and cutting down on sweet, fatty and salty food. Practical steps include adding one vegetable dish to meals out, choosing steamed or boiled dishes more often, and drinking water instead of sweet drinks.

Physical activity

WHO advises adults to do 150 to 300 minutes of moderate-intensity activity, such as brisk walking, each week, plus muscle-strengthening on 2 or more days, and to limit time spent sitting. If you have not been active, start with short walks and build up gradually.

Sleep

The CDC recommends 7 hours or more for adults aged 18 to 60, 7 to 9 hours for ages 61 to 64 and 7 to 8 hours for 65 and over, with the same bed and wake times every day.

Alcohol

The NHS advises men and women not to regularly drink more than 14 units a week, and to spread drinking over 3 or more days if you drink that much, and to have several drink-free days each week. Thailand's dietary guidelines advise avoiding or cutting down on alcohol.

Is it worth changing everything just before the check?

It is better not to make big, sudden changes right before the test.

The results should reflect your normal life

MedlinePlus says the point of preparing is to make sure your results are accurate and reliable. A health check is most useful when it reflects how you usually live, so you do not need to change your habits just for the test.

Don't fast longer than you were told

Follow the fasting time the clinic gives you. MedlinePlus advises asking your provider how long to fast rather than guessing. Skipping meals for days before the check is not part of the usual preparation.

Be honest about what you did

MedlinePlus says even a minor change from the instructions can have a big effect on results, so tell the staff if you did not follow them exactly. Cleveland Clinic says that if you forgot to fast, letting your doctor know can save an unnecessary test, and you may be asked to repeat it while fasting.

What should I bring, and what should I ask the doctor?

A little preparation makes the appointment more useful.

What to bring

• your previous results, if you have them
• a list or photos of every medicine, vitamin and supplement you take
• a note of anything that has changed since the last check, such as sleep, activity, alcohol, work hours or how you feel

What to ask

• what each result means for you, and which ones to keep an eye on
• whether you need another check, and when
• how to prepare before the next check

The results are best explained by the doctor who knows your history. If you have new symptoms or feel unwell before the appointment, do not wait for the check: see a doctor sooner.