If you have ever felt bloated for no obvious reason, struggled to lose weight despite eating reasonably well, felt persistently tired, or been told your blood work is "normal" while still feeling far from it there is a good chance your gut, your hormones, or both are involved.
The research connecting gut health to metabolism, thyroid function, testosterone, sleep, and body composition has advanced enormously in the past decade. Yet most people are still receiving generic advice that addresses none of it.
In this guide, biochemist, nutrition and strength coach Ben Cant walks through what actually moves the needle: from the gut microbiome and digestive symptoms to omega-3 status, hypothyroidism, testosterone, and why regular blood work is one of the most underutilised tools available. If you want to understand your body not just guess at it this is where to start.
The short answer: a lot, with considerably more still to learn.
"In the last 10 years alone I look at what I was researching in practice back then versus now and it's leaps and bounds," says Ben Cant. "But people take the topic of gut health and assume we know everything now. The way to maximise exposure is to make bold claims, whereas more foundational principles of better digestive and gut health are just boring to the consumer."
That gap between what science supports and what gets attention online is exactly where most people go wrong. The fundamentals of gut health are not complicated, and they do not require an expensive protocol. They require consistency, pattern recognition, and honesty about what is actually driving your symptoms.
Most people assume that digestive symptoms bloating, irregular bowel movements, cramping, reflux are always caused by food. In practice, this is often not the case.
"A lot of the time it's not food," Ben explains. "It's because you slept poorly. It's because your stress was very high. It's because you didn't drink any water. It's your schedule."
The contributing factors Ben identifies most consistently in clinical work include:
Food sensitivities are real and worth investigating, but they are often not the primary driver. Starting with an elimination protocol before examining sleep, stress, and schedule is as Ben puts it "looking in the wrong place first."
One of Ben's core clinical tools is formal symptom tracking. Rather than relying on a patient's general impression of how they have been feeling since their last appointment, he assigns numerical values to specific symptoms (bloating severity, stool formation using the Bristol Stool Chart, reflux frequency, and so on) and tracks them over days and weeks.
"You started in January with a severity of 8.6. We are at February and you are at 6.1. March it's at 4.9. I can sit here and say: great, we've had a 21% improvement in the first month, 17% in the second. I can look at the trajectory and make evidence-based decisions."
This approach transforms vague, hard-to-recall impressions into a dataset. Patterns emerge. The cause of a symptom cluster that looked like a food intolerance turns out to be a disrupted morning routine. A string of bad weekends traces back not to what was eaten but to where the person was when they needed to use the bathroom.
The takeaway: if you want to understand your gut, start tracking. A simple notes app or spreadsheet with a daily 1-to-10 symptom score alongside what happened the preceding 12 hours will tell you more in a month than most elimination diets do in six.
The relationship between stress and gut function is bidirectional and well-established. The gut contains roughly 500 million neurons and communicates constantly with the brain via the vagus nerve a connection researchers refer to as the gut-brain axis.
"Stress is evidently a massive factor in gut issues," Ben says. "So big."
Chronic psychological stress activates the hypothalamic-pituitary-adrenal (HPA) axis, elevating cortisol and suppressing digestive function. Blood flow is diverted away from the gut. Gut motility slows or becomes erratic. The intestinal barrier becomes more permeable. The microbiome itself shifts in composition.
Ben has observed this so consistently in practice that his standard framing to clients is: resolve the stress first, then see what gut symptoms remain.
"I joke with Melbourne and Sydney clients: just move to the Gold Coast. I've had so many clients go on holiday and come back saying their symptoms disappeared. And I say: guess what you don't have a gut problem. You have a life problem."
This is not to minimise genuine gut pathology. It is to establish that for a significant proportion of people, chronic low-grade psychological and environmental stress is the primary driver of their digestive symptoms and no supplement protocol will fix that.
Most people in Australia only have blood tests when something is already wrong. Ben's position is that by that point, you are already behind.
"Blood work is one of the best tools we have for identifying things before they become problems," he says. "A lot of very resilient people with discipline and self-control can go far in spite of poor health. The hustle is not necessarily causing it but if you are not getting blood work done and putting symptoms aside, you may not know until you get the brick."
The good news for Australians is that access has improved significantly. Private pathology services allow individuals to order their own comprehensive panels without a GP referral, receive results by email, and then take those results to a specialist of their choosing for interpretation. The cost is often modest particularly when weighed against the cost of operating at suboptimal health for years.
One of Ben's most important points is that reference ranges on blood test results are not the same as optimal ranges. Reference ranges are typically calculated from population averages meaning they reflect what is common, not what is ideal.
"Being in range is got really not a lot to do with being optimal," he says. "It's becoming less and less relevant as time goes on as we become a sicker population."
This matters practically. A testosterone result at the low end of the reference range is not "fine." A thyroid reading within range does not rule out Hashimoto's disease in its early stages. A CRP (C-reactive protein) value that is "not flagged" can still indicate a level of systemic inflammation that warrants attention.
When reviewing your own results, ask not just whether you are within range but where within that range you sit and what the evidence suggests optimal looks like.
Ben is direct about the limitations of mainstream medicine for these kinds of conversations. GPs are trained primarily to identify and treat disease, not to optimise nutrition, micronutrient status, or hormonal health.
"Doctors should be doing what doctors do look for disease, have interventions suitable for that. But on nutrition, they're not trained. A GP saying 'your supplements are just expensive urine' is showing you that anything outside their scope of practice they're going to dismiss."
Red flags when searching for a specialist in this area: practitioners who refuse to be interviewed or appear in long-form content, those who make extreme unidirectional claims without acknowledging opposing evidence, and anyone who cannot clearly explain their reasoning when challenged.
Omega-3 fatty acids, specifically EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), are among the most studied nutrients in the literature. Adequate omega-3 status is associated with reduced cardiovascular risk, lower systemic inflammation, improved brain function, and better metabolic outcomes.
Ben uses the omega-3 index test a simple red blood cell pin-prick test available for around $100 in Australia to assess status objectively, rather than guessing based on dietary intake.
"We know from the data that having an omega-3 index of 8% or above puts you in the lowest risk quartile for many of the things you do not want to get. Under 4% puts you in the highest risk quartile."
The research suggests that to reach an omega-3 index above 8%, a combination of fatty fish intake and supplementation is required. The only group in relevant studies to achieve this threshold ate fatty fish three or more times per week and supplemented with fish oil.
Fish oil supplements are not identical to whole fish consumption. Fish provides selenium, iodine, vitamin D and other co-factors not present in a capsule but for EPA and DHA delivery, a high-quality supplement is a practical and effective option for those who do not eat fish regularly.
Ben's "rule of seven" simplifies the maths:
"Clients love it because you're putting the ownership back in their hands. I don't care what you do have fish or supplements. And they can adjust it as they go."
When selecting a supplement, Ben recommends verifying the certificate of analysis for heavy metals (particularly mercury), oxidation markers (TOTOX values), and the presence of vitamin E, which stabilises the oils and reduces rancidity. On mercury specifically: high fish intake is consistently associated with better health outcomes across the literature, and the net benefit of regular consumption far outweighs the risk for most people eating standard serving sizes of common varieties such as salmon and sardines.
Sleep quality has a direct and measurable impact on gut health, testosterone, thyroid function, appetite regulation, and body composition. Despite being cited constantly as important, it is routinely deprioritised.
Ben describes a pattern he sees repeatedly in clients: late caffeine consumption triggering a cascading effect that compounds nightly.
"Caffeine too late in the day stops people from getting tired at night. Not being tired leads to staying up, using screens, throwing on artificial light. The artificial light suppresses melatonin. Low melatonin disrupts sleep architecture. Then you are also eating close to bed, digesting food, starting the next morning already behind."
Each decision in that chain flows logically from the one before. And because melatonin secretion is disrupted, the quality of sleep even when hours are adequate deteriorates. The consequence shows up the next day in energy, hunger signals, stress tolerance, and digestive function.
Practical priority: set a hard caffeine cut-off of no later than 1 to 2pm. This single change produces downstream improvements in sleep onset, melatonin levels, evening screen time, and overall sleep architecture and it requires no supplementation, no protocol, and no investment.
Hypothyroidism refers to an underactive thyroid gland, insufficient production of thyroid hormones, which leads to a slowing of metabolic processes throughout the body. Hashimoto's thyroiditis (Hashimoto's disease) is the most common cause of hypothyroidism in developed countries, accounting for roughly 90% of cases.
"One is step one, one is step two," Ben explains. "Hashimoto's is an autoimmune condition in which the immune system attacks the thyroid gland. Over time, that damage can impair thyroid function and lead to hypothyroidism."
Common symptoms of hypothyroidism include fatigue, weight gain, cognitive fog, hair loss, dry skin, and constipation. These are also symptoms of many other conditions, which is partly why Hashimoto's is frequently missed in early stages particularly when TSH levels are still within range.
The conventional intervention for hypothyroidism is thyroxin (T4 hormone replacement). This can improve many symptoms of low thyroid function, but it does not address the underlying immune dysregulation driving Hashimoto's.
"It will do nothing to stop the progression of the disease," Ben says.
For those who want to address the root cause, Ben identifies a number of interventions with meaningful evidence:
Selenium: Has been shown to reduce thyroid antibodies by 20 to 30% over approximately 12 months. The thyroid gland contains the highest concentration of selenium of any organ in the body, and selenium plays a key role in thyroid hormone metabolism.
Aloe vera (200ml daily): Associated with reductions in thyroid antibodies of up to 60% over a 12-month period in some studies.
Black seed oil (Nigella sativa): Shown in clinical trials to reduce thyroid antibody levels by up to 50% in as few as eight weeks.
Red and infrared light therapy (low-level laser therapy): European studies have produced striking results using localised laser therapy on the thyroid, with some showing near-complete resolution of thyroid antibodies in a proportion of patients.
Ben also flags a critical caution on iodine: while iodine is essential for thyroid hormone synthesis and is a common online recommendation for thyroid support, supplemental iodine in the context of active Hashimoto's is potentially contraindicated. The immune-mediated damage occurring in Hashimoto's means that increasing iodine availability to an already inflamed gland may accelerate harm. Until antibody levels are under control, Ben advises against supplemental iodine or a diet extremely high in iodine-rich foods.
One of the more striking areas of emerging research is the relationship between gut health and thyroid autoimmunity. Helicobacter pylori, a bacterial infection present in approximately 50% of the world's population, is found in around 70% of individuals with Hashimoto's disease.
Studies treating helicobacter pylori in Hashimoto's patients with standard antibiotic triple therapy have documented drops in thyroid antibodies of 60 to 70% within 30 days of successful eradication.
"I think some of what we're using for Hashimoto's is actually operating on the gut as well as the thyroid," Ben says. "The benefit we're seeing might partly be improvements in gut health that are interlinked with thyroid. Researchers in the 80s and 90s used to call it gastro-thyroid autoimmunity because the link was that tight."
Testosterone declines progressively in men from approximately age 30, with the average rate of decline estimated at around 1 to 2% per year. Low testosterone is associated with reduced energy, impaired body composition, low libido, mood disruption, and reduced exercise performance.
Before considering testosterone replacement therapy, Ben identifies a hierarchy of lifestyle and nutritional interventions that move the needle most reliably.
"Some of the best things you can be doing are making sure you're not overweight, that you're physically active, and that you get good enough sleep."
These three factors are not supplementary they are foundational. Research consistently shows that obesity significantly suppresses testosterone, in part because adipose (fat) tissue converts testosterone to oestrogen via aromatisation. Achieving and maintaining a healthy body composition is among the most impactful single interventions available.
Chronic caloric restriction is also suppressive. Ben notes that very lean individuals particularly those dieting toward competition-level body fat reliably show depressed testosterone and thyroid hormone levels on blood work.
"The body doesn't care about your fertility or optimal thyroid function when it's trying to survive a caloric deficit. It's conserving everything it can."
This has a direct implication for nutrition strategy: aggressive, sustained calorie restriction does not just affect weight it affects hormonal health, sleep quality, immune function, and gut health simultaneously.
Zinc: A well-established cofactor in testosterone synthesis. Ben recommends reviewing zinc status in the context of a full blood panel. Deficiency is particularly common in athletes and in those eating low-meat or plant-heavy diets.
Boron: Less well-known but supported by evidence as a modulator of sex hormone-binding globulin (SHBG). SHBG acts as a "chaperone protein" that binds to testosterone and renders it biologically unavailable. Lowering SHBG via boron supplementation can increase free testosterone even without changing total testosterone levels.
Tongkat Ali (Eurycoma longifolia): The botanical with the strongest current evidence base for testosterone support in men. Ben has observed clinically significant results — including near-doubling of free testosterone levels in some hypogonadal clients though he is careful to note that in a clinical setting these clients were also improving sleep, diet, and stress simultaneously.
"It's hard to tease out exactly how much contribution came from the tongkat ali versus the other changes. But I'm confident enough based on studies and clinical experience to say it can very much be a positive."
Blood test results for testosterone typically show both total testosterone and free testosterone. Total testosterone measures all testosterone in the blood. Free testosterone is the fraction that is not bound to SHBG or albumin and is actually available for use by tissues.
It is entirely possible to have a total testosterone reading within range while free testosterone is genuinely suboptimal particularly if SHBG is elevated (which can occur in response to a low-carbohydrate or ketogenic diet, among other factors).
Ben's view on reference ranges is blunt: "Being in range has really not a lot to do with being optimal. The ranges come from population averages of people attending pathology not from what optimal looks like for a healthy, well-functioning adult male."
He targets closer to the upper end of the range and monitors free testosterone and SHBG alongside total rather than accepting a "not flagged" result as sufficient.
The relationship between body composition, caloric intake, and hormonal health runs in both directions. Optimising gut health and hormones supports better body composition results. And managing body composition thoughtfully in turn protects hormonal health.
This plays out practically in the fat loss versus muscle building conversation. For natural athletes or those working on body composition through nutrition, Ben favours a measured, patient approach over aggressive deficits with the caveat that psychology matters.
"The slower you go with a caloric deficit, the lower the likelihood of hunger problems, craving problems, and gym performance impairment. But you also have a client who leaves you because you took too long."
In practice, the best approach is the one sustainable enough to maintain. Short-term challenges and 8-to-12 week transformations can be genuinely effective but only when they are followed by systems designed to maintain the result, rather than simply marking an end point and walking away.
Apps like INCHECK FIT are designed around exactly this challenge: removing the manual calculation burden while keeping nutrition adaptive recalibrating targets as progress changes so the plan keeps working week to week, not just for the first eight weeks.
How long does it take to improve gut health naturally? Meaningful improvements in digestive symptoms can occur within two to four weeks when the primary drivers are addressed most commonly sleep quality, stress, hydration, and routine. More complex presentations, such as those involving gut infections or autoimmune components, typically require three to six months of targeted intervention.
What are the most common causes of bloating in adults? Stress, poor sleep, disrupted bowel routine, dehydration, gut dysbiosis, and certain dietary intolerances are the most common causes. Gut infections, including helicobacter pylori, are frequently overlooked. Food sensitivities, while real, are often not the primary driver.
What is the omega-3 index test and how do I do it? The omega-3 index test is a red blood cell analysis that measures the percentage of omega-3 fatty acids (EPA and DHA) in red blood cell membranes. A result above 8% is associated with the lowest risk quartile for cardiovascular and inflammatory disease. The test is available as a home pin-prick kit in Australia for approximately $100.
How do I know if I have Hashimoto's rather than regular hypothyroidism? Hashimoto's is confirmed by testing thyroid antibodies (anti-TPO and anti-thyroglobulin antibodies) alongside standard thyroid hormone panels (TSH, T3, T4). Antibodies can be elevated even when TSH is still within range, which is why standard GP panels often miss early Hashimoto's. If you have symptoms of low thyroid function and a family history of autoimmune conditions, requesting a full antibody panel is worthwhile.
What is the best natural way to increase testosterone? The foundational steps with the strongest evidence are: maintaining a healthy body weight, exercising regularly (particularly resistance training), getting consistent high-quality sleep, and avoiding prolonged severe caloric restriction. Beyond these, zinc and boron status are worth reviewing via blood work, and tongkat ali (Eurycoma longifolia) has the strongest evidence base of the available botanical options.
Is fish oil a good substitute for eating fish? For EPA and DHA delivery specifically, a high-quality fish oil supplement is an effective substitute. Whole fish provides additional nutrients (selenium, iodine, vitamin D) that a supplement will not replicate. The "rule of seven" is a practical guide: aim for 700g of fatty fish per week, and for every 100g below that, take one high-strength fish oil capsule per day.
Can stress really cause digestive problems? Yes. The gut-brain axis is a well-established bidirectional communication network. Chronic stress elevates cortisol, suppresses digestive motility, increases intestinal permeability, and alters the gut microbiome. Many people find that digestive symptoms improve substantially when stress is reduced sometimes without any changes to diet.
What blood tests should I be getting regularly? A comprehensive annual panel should include: full blood count, thyroid function (TSH, T3, T4, and thyroid antibodies), testosterone (total and free), SHBG, sex hormones, metabolic markers (glucose, insulin, HbA1c), liver and kidney function, inflammation markers (CRP, homocysteine), vitamin D, zinc, ferritin, and lipid panel. Many of these are not included in a standard GP annual check-up but can be requested or accessed through private pathology services.
Last reviewed: March 2026 by the INCHECK FIT nutrition team.
