Could Your Anxiety Be Starting In Your Gut?

Butterflies before a big meeting. A tight stomach when something feels off. Suddenly losing your appetite or feeling bloated during a stressful week. We tend to think of anxiety as a purely mental state, but for some, it can feel incredibly physical.

That’s one reason researchers and clinicians have become increasingly interested in the gut–anxiety connection. Why do stress and anxiety so often show up in digestion? And can what happens in your gut truly affect how anxious you feel? 

According to experts, the relationship goes both ways. “Anxiety starts in the brain, but it can also start in the gut, as the pair act together in a continuous two-way system,” says nutritionist Kirsten Brooks, BSc Hons DN Med, also known as “The Brain Health Nutritionist”.

That doesn’t mean every anxious feeling comes down to digestion. Anxiety is complicated and typically shaped by psychological and physiological factors that feed into one another. “It’s worth saying first that anxiety can be a normal and healthy part of being human,” says Dr. Edward Caddye, PGCert, MB BCh BAO, a metabolic psychiatrist and medical doctor at London Psychiatry Clinic. “It only becomes something we’d diagnose and treat in psychiatry when it’s chronic and severe enough to interfere with daily life.”

Still, the gut–anxiety connection is becoming harder to dismiss.

What is the gut-brain axis? 

Much of this comes back to something called the gut–brain axis. Brooks describes it as the two-way biochemical and neural communication network linking your brain and your gut. “The two talk to each other via the enteric nervous system, neurotransmitters, the gut immune system, and gut hormones,” she says. It may sound complicated, but it helps explain why stress so often shows up in digestion when anxiety is high, from nausea and bloating to suddenly losing your appetite.

The gut contains more than 100 million nerve cells and is heavily involved in serotonin production, one of the neurotransmitters linked to mood. “The gut is sometimes called our ‘second brain’ because of the large number of neurons in the enteric nervous system,” says Dr. Caddye. “It’s a two-way street. The brain influences the gut, and the gut sends signals back.”

One of the key links here is the vagus nerve, which carries signals between the gut and brain. Dr. Caddye says it helps integrate everything from social stress to changes in gut chemistry.

Can poor gut health affect anxiety?

Sometimes, yes, though the relationship is not always straightforward. For some, anxiety may begin with psychological stress, a difficult relationship, work pressure, burnout, or past trauma. But what is happening in the body can influence how intense anxiety feels too, or how difficult it is to shake. “Physiological contributors can include things like disrupted sleep, blood sugar swings, and poor nutritional status,” says Dr. Caddye.

Gut health may sit alongside that too. “Imbalances in gut bacteria or gut inflammation can trigger changes in neurotransmitters,” says Brooks. “These physical changes send chemical stress signals up the vagus nerve, triggering or worsening symptoms of anxiety and mood changes.” This also helps explain why anxiety and digestion so often overlap. Indigestion, bloating, diarrhoea, constipation, nausea, and IBS symptoms can all become more noticeable when stress is high.

That doesn’t mean digestive symptoms are “all in your head.” Often, the opposite is true. Anxiety can affect digestion, digestion can influence mood, and the two can end up reinforcing one another. Poor gut health can make stress feel harder to shake. Stress can then affect digestion further, which helps explain why anxiety and gut symptoms often seem to feed off one another.

Why anxiety shows up in your stomach

Anxiety tends to hit the stomach for a reason, and much of it comes down to how the body responds to stress. “The gut is sometimes called our ‘second brain’ because of the large number of neurons in the enteric nervous system,” says Dr. Caddye. “This connects to the autonomic nervous system, which adjusts gut motility in response to stress so the body can direct its energy where it’s needed.”

What that means in real life is that digestion often works differently when stress is high. Food may move through the gut more quickly or more slowly. Stomach acid can change. Muscles in the digestive tract can tighten. For some people, appetite disappears completely. For others, digestion suddenly feels uncomfortable or unpredictable.

Brooks says gut symptoms linked to anxiety can vary hugely. “Indigestion, heartburn, gastritis, bloating, diarrhoea, constipation and IBS symptoms can all show up,” she says. It also helps explain why IBS and anxiety so often seem to arrive as a pair. Stress can throw digestion off, while unpredictable gut symptoms can leave people feeling more anxious too, especially when eating out, travelling or even making plans starts feeling harder to navigate.

Four places worth looking if anxiety feels physical

How you sleep, eat, move, and handle stress can all influence both mood and digestion. Dr. Caddye says many of the biggest drivers tend to overlap. “Common contributors include a sedentary routine, a diet heavy in ultra-processed foods, too little or excessive exercise, micronutrient deficiencies, inadequate protein and essential fatty acids, insufficient calories overall, poor sleep, disrupted circadian rhythms and sustained high stress,” he says.

Stop accidentally making anxiety worse with blood sugar crashes

If anxiety tends to hit hardest mid-morning or late afternoon, Dr. Caddye says blood sugar can be a big physiological contributor. When blood sugar drops too quickly, often after skipping meals, surviving on coffee, eating something sugary on its own, or going too long without food, the body releases stress hormones to bring levels back up again. The tricky bit is that this can physiologically feel very similar to anxiety: shaky hands, racing thoughts, feeling irritable for no obvious reason, suddenly feeling overwhelmed by something that felt manageable an hour earlier.

Brooks also says blood sugar is one of the first things she looks at when someone feels anxious, wired, or physically “off”. Keeping blood sugar steadier doesn’t mean eating perfectly or cutting carbs. It usually comes down to eating in a way that keeps energy more stable, so the body isn’t constantly trying to catch up. A few things worth trying:

• Aim for 20–30g of protein at breakfast. Think eggs, Greek yoghurt, tofu, or protein oats within a few of hours of waking
• Pair carbs with protein or fats so energy lasts longer. Toast with eggs or nut butter lands very differently to toast on its own
• Avoid going more than four to five hours without eating if anxiety tends to hit harder when you’re hungry or running on caffeine
• Eat before you are starving, because 3pm grab-whatever-is-left lunches won’t keep energy steady

One useful thing to notice is when anxiety tends to show up in your day. If it often appears when you’re hungry, tired, over-caffeinated, or have forgotten to eat, it may be worth experimenting with steadier meals before assuming something bigger is going on.

Aim for 30 different plants a week to support a calmer gut

Feeding your gut bacteria better is another useful place to start. The gut microbiome, the trillions of bacteria living in the digestive system, does far more than help digest food. It influences inflammation, immune function, and how the gut and brain communicate, including systems involved in mood and stress resilience.

The bacteria thriving in your gut partly depend on what you eat. Fibre and plant foods help support a more diverse microbiome, something researchers increasingly associate with better gut health and a more resilient nervous system overall.

Brooks says she almost always starts with food before looking at supplements when both digestion and mood feel off. “It’s all about getting the foundations right of a good balanced diet with quality protein, fibre for the gut microbiome, good fats and slow release carbohydrates,” she says. “Lots of polyphenols from different coloured fruit and vegetables help feed the gut microbiota and reduce inflammation.”

One of the easiest ways to support your gut microbiome is by simply adding more variety to your meals. Rather than chasing the “perfect” diet, aim for 25 to 30 different plant foods across the week. It sounds like a lot, but herbs, oats, berries, lentils, nuts, seeds, beans and vegetables all count, and small additions can add up quickly.

Dr. Caddye says around 30g of fibre a day is a sensible target to strive for, though if bloating is already an issue, building up gradually tends to feel much gentler than suddenly doubling fibre overnight. This tends to be more about small additions than overhauling your diet. For example:

• Add one extra plant food a day, lentils stirred into soup, seeds on yoghurt or beans with dinner
• Rotate fruit and vegetables instead of buying the same few every week
• Include fermented foods two or three times a week if they suit you, yoghurt, kefir, kimchi or sauerkraut
• Focus on what you can add to meals rather than what needs cutting out

A more diverse plate often ends up being a more microbiome-friendly one too.

Make sleep more predictable

Poor sleep has a habit of making anxiety feel louder and digestion more sensitive. After a bad night, we often feel more reactive, hungrier, and quicker to reach for caffeine or sugar, all things that can leave blood sugar and gut symptoms feeling more unsettled too. It’s also why anxiety can suddenly feel much harder to manage.

Dr. Caddye says insufficient sleep and disrupted circadian rhythms are common contributors to both gut symptoms and mood changes. There is some biology behind that too. Sleep influences stress hormones, blood sugar regulation and the nervous system, which means a few disrupted nights can leave the body feeling more wired, emotionally reactive and generally less steady.

Sleep tends to work best when the body knows roughly what to expect. A few habits worth trying:

• Get 10–15 minutes of daylight within an hour of waking
• Keep caffeine earlier in the day, especially if anxiety already feels quite “wired”
• Try keeping wake-up times fairly similar, even on weekends
• Eat enough during the day so you are not ending up ravenous at night

Exercise for your nervous system, not just fitness

If anxiety feels high, movement can help in more ways than one. Exercise can support stress regulation, blood sugar balance and sleep, all things tied to how resilient we feel mentally.

The type and intensity of your movement make a difference. Too little can leave stress sitting there. Conversely, going too hard can sometimes backfire too, especially if you're under-eating, not getting enough sleep, or already overwhelmed. Long runs, back-to-back HIIT classes, or constantly training to exhaustion can leave some people feeling even more wired.

Dr. Caddye points to “well-tailored exercise” as something that supports emotional resilience rather than leaving you feeling more depleted. Most of the time, movement tends to work best when it helps the nervous system settle rather than pushing it harder. The aim isn’t to wipe yourself out, just feel better than before.

You don’t need an intense training plan for this to count. Small things done regularly tend to go further:

• Walk for 10–15 minutes after meals, especially lunch or dinner
• Lift weights two or three times a week, not every day
• Get outside daily, even briefly

How you feel an hour later is often useful intel. Feeling clearer headed, more grounded or generally better than before is usually a good sign, but feeling wiped out, overstimulated, or depleted may be a sign intensity needs adjusting.

Be more selective with probiotics

Probiotics have become one of the biggest talking points in gut health, particularly around something researchers call psychobiotics, strains experts are exploring for their potential effect on mood and mental wellbeing. The research is interesting, though not nearly as straightforward as “take this and feel less anxious”.

“For some people, probiotics do seem to support wellbeing, but the evidence is mixed and very individual,” says Dr. Caddye. Part of the challenge is that probiotics are incredibly specific. Different strains appear to do different things, which means what works for someone with bloating, IBS symptoms, or digestive disruption after antibiotics may look completely different to support aimed at stress or low mood.

This is one area where guesswork doesn’t always pay off. If symptoms feel persistent, Brooks says personalised support can be especially useful. Testing, food changes or targeted support may tell you more than buying whichever probiotic happens to be trending.

When anxiety is worth getting support for

Not every anxious feeling needs fixing. Anxiety is part of being human and most people will experience it at some stage. That being said, there’s a difference between feeling anxious and feeling stuck in anxiety. “It only becomes something we’d diagnose and treat in psychiatry when it’s chronic and severe enough to interfere with daily life,” says Dr. Caddye.

If anxiety is affecting sleep, appetite, relationships, concentration, work, or how safe and settled you feel day to day, it’s worth speaking to someone. Equally, if gut symptoms feel persistent, unpredictable, or are starting to affect how you eat, socialise, or leave the house, support is worth considering there too.

Gut health may influence how anxiety feels for some people, but anxiety is not usually explained by one thing alone. Looking after digestion, blood sugar, sleep, and stress can all help, though it should never feel like you have to figure everything out by yourself or delay getting proper support when you need it.