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GB Fitness is an exercise and nutritional consultancy designed for anyone who seeks to improve their health, vitality, physique, performance, emotional happiness and more. From Rehabilitation to Elite Athletes, from bespoke Corporate Programs to clients with medical issues – GB Fitness has benefitted people from all walks of life – and offers something for everyone.

We are also an award winning Training Provider of internationally acclaimed qualification courses in Personal Training, Nutrition, First Aid for Mental Health and more.

Founder Cain Leathem has studied anatomy and physiology, massage, exercise prescription, nutrition, supplementation, clinical analysis, biomechanics, endocrinology, phlebotomy, DNA testing, First Aid for Mental Health, N.L.P. and many related disciplines. He prides himself on the comprehensive range of academic studies that he has undertaken over 30 years and he has utilised his expertise and experience worldwide.

As a Professional Speaker and Educator he has advised and taught thousands of clients including some of the very best Health Advisors in the industry.

Cain Leathem GB Fitness Founder

This will vary in emphasis depending upon the client’s needs but generally consists of:

  • Full body composition assessment (fat mass, lean mass, hydration level and calorie expenditure)
  • Blood pressure and heart rate checks
  • Assessment of the client’s current dietary program and lifestyle
  • Blood tests and more (samples taken and sent to leading CQC approved labs for analysis if required)

Then an individual and mutually agreed eating plan will be constructed, with a view to achieving the client’s desired goals, along with a supplementation program if required.


After some detailed information has been provided by you Cain will design and advise on bespoke plans to ensure that you have the best path towards achieving your goals. He can also offer face to face assessments and instruction on exercise techniques so that you can be confident and sure that what you are doing is both safe and effective. Regular check-ins and reviews can be arranged to make the journey progressive and successful. Accountability is a key factor in an on-going process, so make sure that you work with the very best of professionals in their area of expertise and please be honest with what you want to achieve and what you are doing to get there.

We, at GB Fitness, do not give generic, one-size-fits-all programs or advice. Traditionally our best work is given in a face to face scenario. This is not always possible, or convenient, for the client. As such provisions can be made to offer the very best of modern technology so that we may offer consultations, individualised advice and accountability to our valued clients. This may include health assessments and testing (which can be arranged to be done locally to you or even at your home), exercise and nutrition advice and all importantly to keep you focused and motivated on reaching your goal. We want you to achieve whatever it is that will enhance your health and your life.

Please make contact to discuss the best solution for YOU!

As a qualified phlebotomist Cain is able to take your blood, via venepuncture, if required. Some tests are finger prick/blood spot and can be done by yourself at home.

A wide range of testing is available through highly respected labs such as The Doctors Laboratory in London, Blue Horizons, York Test and others. We can build a bespoke profile for you that may include:

  • Blood Cholesterol (the all-important HDL/LDL ratio, not just a total figure)
  • Blood Glucose and HbA1c (Type II Diabetes Risk)
  • Full Biochemistry Profile that includes Liver Enzymes, Electrolyte levels, Iron Status, Red and White Blood Cell count, Triglycerides, Iron and Ferritin status and more
  • Cardiovascular Disease Development Risk Assessment
  • Female/Male Hormone Panel (we at GB Fitness have personally designed and developed extended profiles that give answers where more basic tests cannot)
  • Thyroid/Adrenal Function Tests (TSH, T4, Free T3, Thyroid anti-bodies and DHEA/Cortisol etc.)
  • Immune/Viral Assessment Profiles (including Covid anti-bodies)
  • Vitamin/Mineral/Essential Fats/Toxin level status
  • Allergy/Intolerance Screening (IgE, IgG etc.)

 Upon completion of the tests, participants are given a report of the results and key recommendations towards making the appropriate healthy lifestyle choices that are individually tailored to each client to facilitate the achievement of this Optimal Health goal. All results are kept in the strictest confidence.

An at-home bloodspot and saliva test that assesses many parameters than may cause an issue with fertility.

Hormone-related causes of female infertility most often involve the following five scenarios:

Ovarian Insufficiency
Polycystic Ovarian Syndrome (PCOS)
Hypometabolism/Thyroid Deficiency

The markers tested are:

Oestradiol (E2)
Progesterone (Pg)
Testosterone (T)
Diurnal cortisol (C) sampled four times during a day (via saliva)
Thyroid hormones (TSH, Free T3, free T4, and TPO antibodies)

The Gastrointestinal Microbial Assay Plus (GI-MAP) was designed to assess a patient’s microbiome from a single stool sample (the kit and instructions are supplied, with test sample to be done at home and collected via DHL), with particular attention to microbes that may be disturbing normal microbial balance and may contribute to disruptions and issues in the gastrointestinal (GI) flora or an illness. The panel is a comprehensive collection of microbial targets as well as immune and digestive markers (including pancreatic function). It screens for pathogenic bacteria, commensal bacteria, opportunistic pathogens, fungi, viruses and parasites. It primarily uses multiplex, automated, DNA analysis to give integrative and functional medicine practitioners a better view into the gastrointestinal microbiome. Zonulin has been identified as a key biomarker for intestinal permeability, which has been associated with food/drink intolerances, coeliac disease, non-coeliac gluten sensitivity (NCGS) and other GI and systemic conditions.

A home test kit via urine and saliva with courier collection from your home/workplace. The DUTCH Plus takes comprehensive hormone testing to a whole new level. In addition to sex hormones and their metabolites, as well as brain neurotransmitters the test also looks at the overall diurnal pattern of free cortisol, and the total and distribution of cortisol metabolites. The DUTCH Plus adds the Cortisol Awakening Response (CAR) to bring another important piece of the HPA axis into focus.

A low or blunted Cortisol Awakening Response can be a result of an underactive HPA axis, excessive psychological burnout, seasonal affective disorder (SAD), sleep apnea or poor sleep in general, PTSD, chronic fatigue and/or chronic pain. A decreased CAR has also been associated with systemic hypertension, functional GI diseases, postpartum depression, and autoimmune diseases. 

An elevated Cortisol Awakening Response can be a result of an over-reactive HPA axis, ongoing job related stress (anticipatory stress for the day), glycaemic dysregulation, pain (i.e. waking with painful joints or a migraine), and general depression. This measurement of the response to waking has independent clinical value showing dysfunction that may be hidden by current testing options.

Women: Millions of women suffer from hormonal imbalances. Identifying the root cause of chronic health issues is certainly correctable, but only if properly identified. The dried urine collection process is great for baseline measurements of women with hormonal imbalances and for Hormone Replacement Therapy (HRT) monitoring. Several of the metabolites that are measured can potentially impact us in a negative way but having the data means the correct protocols can be applied to help keep you optimally healthy.

Men: Over time, men experience a gradual loss of their hormones that are produced in the gonads and adrenal glands. Testosterone and DHEA levels fall and oestrogen levels (E1, E2, E3 and metabolites are all measured) tend to rise. Many men feel like this is part of getting older and do not think there is treatment to help them maintain a healthy lifestyle. The DUTCH test was created to provide insight, in one easy to administer test.

The DNA tests offer profiles that focus on Health, Nutrition, Exercise and Fitness, Mind and more. They are designed to give us an insight into your individual genetic make-up and how to optimise well-being and health by personalising lifestyle and diet choices and, where necessary, using supplements tailored to offset any particular nutritional deficit based on specific gene variants.

The DNA Health approach (the most popular choice of profile) assists the healthcare practitioner in establishing the optimal nutrition necessary for good health, longevity and disease risk mitigation. Diet is a key factor in determining genomic stability as it impacts on all relevant pathways:  exposure to dietary carcinogens, biotransformation, DNA repair and synthesis, and apoptosis. Current recommended dietary allowances for vitamins and minerals are based largely on the prevention of diseases of deficiency. However, because diseases of lifestyle are partly caused by damage to DNA it stands to reason that we should focus our attention on defining optimal requirements of key minerals and vitamins for preventing genomic instability.

Clinical Value

  • Highlights specific metabolic pathways that may require extra support
  • Provides recommendations that involve optimisation of quantities of certain nutrients, vitamins and minerals
  • Suggests whether an individual is better able to improve their health through lifestyle changes, as opposed to through medication
  • Provides an indication of the degree of susceptibility to the harmful effects of carcinogens ingested in the diet and from the environment etc.

A simple at-home Vitamin D Test that determines your current vitamin D levels (both D3 and D2). The kit is a finger prick, blood spot test and the report gives easy to understand reference ranges based on optimal levels for best health outcomes. Vitamin D is one of the most important vitamins of all, with wide-ranging functions across the body – including bone formation, muscle function, mood, hormone regulation, and immune support. Low levels of vitamin D have been linked to an array of health problems and deficiencies and sub-optimal levels (including the reference ranges given by the NHS) are common. Individual recommendations will be given on protocols and dosage according to the results.

The Metabolomix + is a unique combination of nutritional tests that provides an analysis of key nutritional biomarkers. Metabolomix + nutritional test is a non-invasive, patient-friendly way to assess the functional need for antioxidants, B-vitamins, minerals, digestive support,  amino acids urine elements (as an add-on) and fatty acids (as an add-on).

The test covers:

Organic Acids
Malabsorption and Dysbiosis
Cellular Energy and Mitochondrial Metabolites
Neurotransmitter Metabolites
Vitamin Markers
Toxin and Detoxification Markers
Tyrosine Metabolism
Oxalate Markers
Amino Acids
Nutritionally Essential Amino Acids
Non-essential Protein Amino Acids
Intermediary Metabolites
Dietary Peptide Related Markers
Oxidative Stress Markers

Essential and Metabolic Fatty Acids – Bloodspot
(if selected as add-on profile)
Omega 3 Fatty Acids
Omega 6 Fatty Acids
Omega 9 Fatty Acids
Saturated Fatty Acids
Monounsaturated Fatty Acids
Delta-6 Desaturase Activity
Cardiovascular Risk
Nutrient and Toxic Elements (if selected as add-on profile)

The information gained will mean that we can really zero in on any issues and the protocols employed will give a very unique and bespoke plan of action to maximise your health.

A simple yet comprehensive at home, finger prick test to assess over 200 food and drink ingredients that you may have negative reactions to. Simply take a finger-prick blood sample and return by post and receive your results within 7 days. We then work with that information to optimise your nutrition and lifestyle with our support, knowing which foods/drinks that you are reacting to. Protocols can also be given to improve overall gut health.

All four subtypes of food/drink-specific IgG (1-4) are tested compared to some other tests that only look for IgG4. This is important as it ensures all of the different food-specific IgG reactions are detected.

Your gut is home to 70% of your immune system and controls optimal delivery of nutrients to your bloodstream and protects us from unwanted toxins and more. You can support your gut health by reducing your ‘immune load’, and removing ingredients from your diet that may be causing it to overwork and could be triggering unwanted symptoms and health issues.


As a Professional Speaker Cain has spoken at many conferences, exhibitions and corporate training events. He is in demand worldwide and educates at business summer schools abroad as well as teaching his award-winning qualification courses in countries that include Kuwait, Bahrain and Grand Cayman. This video will give you a quick insight of his work.


Cain can been seen here holding a day of in-depth training for past and current students of GB Fitness. His workshops, seminars and masterclasses are attended by health professionals, medical experts, elite athletes, coaches and anyone who wants to learn ‘The Truth about OPTIMAL Health’.  Make a call and have a chat about what he can offer you.


Cain has had a passion for all things health (both physical and mental) for 30 years’. Here he is speaking after winning The English Veterans Award for Contributions to Fitness and Society. His own extensive education and training  means that he can offer a wide range of specialist services to those that value the best help and advice.


A range of bespoke tests can be offered including blood work, stool testing, DNA assessments and more. Specialised labs from around the world are utilised to ensure the most comprehensive information is gathered to maximise the effectiveness of the recommendations given. Please contact me to discuss the multitude of options available.


Cain is a Professional Speaker and speaks internationally on all matters of health and optimal being. His clients include executives and forward thinking leaders in business. As a senior member of the Royal Society of Medicine he is at the cutting edge of advancements and research in health, fitness and medicine. He encourages an attitude of: 
“WE do today what others will do tomorrow!”


Watch Cain’s video about  what Anxiety is and strategies to help you change your focus.


DOWNLOAD Cain’s FREE Top 10 Tips. Providing you with guidance on how to stay fit and healthy 


Stay flexible with Cain’s Stretch Exercise Routine. Click the link for your FREE DOWNLOAD


DOWNLOAD your FREE Step by Step guide to Cain’s Band Workout Session


If you would like to speak in more detail, please feel free to contact me. Let's talk!

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