Blood Tests for Weight Loss in London
Medical Weight Loss London arranges blood tests for weight loss in London as part of a consultation with a registered clinician at UNTIL Soho: six tests that find the medical reasons weight changes.
The short answer
Which blood tests help with weight loss?
The blood tests that matter for weight loss are thyroid function, HbA1c, a lipid profile, liver function, kidney function and a full blood count. Between them they find an underactive thyroid, prediabetes or diabetes, raised blood fats, a fatty liver and the other conditions that either cause weight change or travel with it.
A normal set of results is useful too. It rules out the causes that would change the plan and gives you a baseline to compare in six months. The tests are arranged by the clinician at a weight loss consultation, who reads them against your history.
The tests at a glance
- Core testsSix
- Single test in London£43 to £99
- ResultsDays to a few weeks
- GP referralNot needed privately
The six core blood tests for weight
Thyroid blood test
Measures thyroid stimulating hormone (TSH) and free T4. An underactive thyroid causes tiredness and weight gain, and it is found with this test. London price: about £45 to £99.
HbA1c test
Shows your average blood sugar over about 3 months. 42 to 47 mmol/mol is the prediabetes range and 48 or above points to type 2 diabetes. London price: about £43 to £79.
Lipid profile test
Measures cholesterol and triglycerides. High triglycerides and low HDL cholesterol are part of the pattern called metabolic syndrome. London price: about £45 to £73.
Liver function test
Raised liver enzymes are often the first sign of a fatty liver, which is common at higher weights and usually causes no symptoms. London price: about £45 to £69.
Kidney function test
Urea and electrolytes check how well your kidneys filter, which matters before any change in diet or activity and alongside raised blood pressure. London price: about £45 to £79.
Full blood count
Checks red and white cells and platelets. Anaemia, for example, causes tiredness that is easy to mistake for low motivation. London price: about £54 to £65.
Blood tests for weight gain you cannot explain
When weight has gone up without a change in how you eat or move, the same six tests are the starting point, because they find the commonest medical causes: an underactive thyroid, rising blood sugar and a fatty liver. The clinician may add others when your history points to them, such as a cortisol test when the pattern suggests Cushing’s syndrome, or hormone tests around the menopause.
There is no single routine test for insulin resistance in UK practice: HbA1c, a fasting glucose and a lipid profile show its effects, which the insulin resistance page explains. The unexplained weight gain page sets out the other causes and which test separates each one.
Private blood test cost in London
A single private blood test in London costs about £43 to £99, depending on the test and the lab, in published prices checked on 30 September 2026 at OneDayTests, London Doctors Clinic and Blue Horizon. A 22-marker weight management panel costs £125 at OneDayTests, and some labs add a collection fee: Blue Horizon adds £30 for a finger-prick kit.
Medical Weight Loss London sets no price for tests. The clinician at your consultation arranges the ones you have not already had and confirms the cost before anything is taken, and the consultation itself costs about £150 to £310 at London clinics.
Getting blood tests on the NHS
Your GP can arrange these tests on the NHS when there is a clinical reason, such as symptoms of an underactive thyroid or a family history of diabetes. If your GP has run any of them in the last few months, bring the results to your consultation so they are not repeated. Private tests buy speed and a clinician who reads them against a weight history; they do not replace your GP, and the results should be written to your NHS record.
Fasting, results and what happens next
Whoever arranges the tests tells you whether to fast beforehand. Bring any results from the last few months so they are not repeated. Results usually come back within a few days to a few weeks, and a clinician goes through them with you and sets the plan around them.
If everything comes back normal, that is the commonest result and it is useful: the plan moves on to sleep, alcohol, medicines and activity, and the medical weight loss programme page covers what that plan should contain.
FAQ
Blood tests for weight loss
questions
Which blood tests help with weight loss?
Thyroid function, HbA1c, a lipid profile, liver function, kidney function and a full blood count. Together they find an underactive thyroid, prediabetes, raised blood fats and a fatty liver. Medical Weight Loss London lists them so you can check a consultation or a quote includes all six.
How much does a private blood test cost in London?
About £43 to £99 for a single test, in published London prices checked in September 2026, and £125 for a 22-marker weight panel at OneDayTests. Some labs add a collection fee. Medical Weight Loss London sets no price for tests; the clinician confirms the cost first.
Do I need to fast before a weight loss blood test?
Sometimes. Whoever arranges the tests tells you, because a fasting glucose or some cholesterol tests need it while HbA1c reflects the past few months. Medical Weight Loss London suggests asking when the tests are booked, so you do not have to go back a second time.
Can I get these blood tests free on the NHS?
Often, yes, when your GP has a clinical reason to request them, such as symptoms of an underactive thyroid. Medical Weight Loss London suggests bringing any recent NHS results to your consultation, so the private tests cover only what is missing.
How long do blood test results take?
The NHS says you may get results after a few days, and usually within a few weeks. Private labs are often quicker. Medical Weight Loss London recommends agreeing at the consultation who will go through the results with you, because a number on a portal is not an explanation.
Related Services
Get Started
A person reads every enquiry that arrives here.
The assessment is arranged with a clinician who can see you.
Medical Weight Loss London • UNTIL, 111 Charing Cross Road, London WC2H 0DT
Ask What to Get CheckedThe enquiry goes to UNTIL Health Concierge, and the assessment that follows is with a clinician who can order the tests.