Why Does Stress Make Us Ill?

Stress gets blamed for everything, yet a little of it is genuinely good for you. So why does stress make us ill? In this episode, Jen, Chris and Jamie unpack one of the most misunderstood ideas in health. Stress on its own isn't the problem. The problem is a system that's brilliant in short bursts but never gets switched off. The team walks through the two systems that fire when your brain senses a threat, why chronic stress is now ranked alongside smoking as a heart risk, and how the same chemistry that saves you in a five-minute scramble starts wearing down your heart, immune system, brain, muscles and gut when it runs for months. Along the way there's a kitchen full of guests who never leave, a healthy dose of Captain Sensible, and a clear, evidence-based look at what actually helps. The goal was never a stress-free life. It's an off switch that works as well as the on switch. In this episode: 00:04 When stress is actually on your side 01:22 How big is the problem 03:48 What stress actually does to your body 06:29 Stress, your heart and your immune system 09:22 Brain fog, gut knots and the ageing effect 12:47 What actually moves the needle 17:22 The goal was never a stress-free life The Good Kind of Stress Has a Name (00:04) Not all stress is the enemy. The nerves before a big presentation or the push before a deadline can sharpen you up, and there's even a word for the helpful kind: eustress. The trouble is that most of us aren't living in short bursts anymore. We're living in the chronic version that never lets go. "I spent years blaming stress for everything, bad mood, lost keys, the lot. Now you're telling me it was on my side the whole time?" Jamie A survey of more than 145,000 adults across 144 countries found more than one in three had felt significant stress on an ordinary day The World Health Organisation counts over a billion people living with a mental health condition In the UK, around 964,000 workers were dealing with work-related stress, anxiety or depression across 2024 and 2025, the sharpest single-year jump on record Your Body Reacts Like a Kitchen Before Guests Arrive (03:48) When your brain senses a threat, two systems fire. A fast one floods you with adrenaline, raising your heart rate and blood pressure. A slower one releases cortisol, which keeps your energy topped up by quietly turning down anything non-essential, including digestion, repair and part of your immune system. "You get a text that guests are arriving at the door in five minutes. Everything urgent gets done immediately. The gas goes on, the hob's on full. That's the adrenaline." Jamie For a short scramble, your body is brilliant at this. The problem is the version where the guests never leave, the hob stays on full day after day, and the upkeep never happens. Chronic Stress Wears the Body Down System by System (06:29) Run that emergency chemistry for months instead of minutes, and the damage shows up everywhere. Chronic stress is now treated as an independent risk factor for cardiovascular disease. Heart: A 2023 study found depression and anxiety raised the risk of a major heart event by about 35% and brought warning signs forward by roughly six months. It doesn't hand you a heart attack on the spot; it moves the timeline forward Immune system: Short bursts sharpen your defences, but sustained cortisol suppresses them, which is why you often fall ill the first day of the holiday Brain, muscles and gut: The hippocampus can shrink under a long soak in cortisol, muscles brace into tension headaches and a tight neck, and digestion drops out, leaving that knotted feeling "Walking into a room and forgetting why you went there isn't you being hopeless. It's just chemistry." Jamie What Actually Moves the Needle (12:47) The strongest evidence is for movement, and the dose is gentler than most people think. Around 20 minutes of something moderate on most days lowers cortisol and improves sleep. Consistency beats intensity, breathing helps in the moment, sleep and social contact both steady the system, and if stress is genuinely affecting your health, that's a conversation with a doctor rather than a podcast. "The best exercise is one that you will actually do." Jamie About So That's Why So That's Why is a weekly podcast where Jen, Chris and Matt unpack the science behind everyday health questions. No jargon, no judgment, just genuine curiosity and proper research. Website: https://www.vegetology.com/so-thats-why-podcast