So That's Why

Nearly 90% of adults consume caffeine daily — yet most have no idea why it gradually loses its punch. If your morning coffee used to change your day and now just stops you feeling terrible, there is a biological reason for that. And it happens faster than you would expect. In this episode, Jen, Chris, and Jamie unpack the science of caffeine tolerance: what adenosine is and why it matters, how you...

Your body can make Vitamin D from sunlight — so why is nearly half the global population still deficient in it? In this episode of So That's Why, Jen, Chris, and Matt unpack what Vitamin D is actually doing inside the body, why the sunshine route fails so many people, and why deficiency shows up as fatigue, frequent illness, and muscle weakness rather than just weak bones. Along the way, they bust...

Cholesterol is in every single cell in your body — yet it's also called "the Silent Killer." In this episode, Jen, Chris and Matt unpack why the same molecule that keeps you alive can silently damage your arteries for decades before you feel a thing, and what you can actually do about it. In this episode: 00:00 — Introduction 01:02 — Why cholesterol has such a confusing reputation 02:09 — The scal...

That irritable, short-fused feeling when you've missed a meal has a name — and it turns out "hangry" is backed by serious science, not just a lack of willpower. In this episode, Jen and Chris are joined by Jamie for a deep dive into why hunger hijacks your mood. The team unpacks four separate biological mechanisms that fire simultaneously when blood sugar drops: stress hormones that can't be disti...

Why do onions make us cry every time we cut them — and why does cooking them make the problem disappear completely? About 70% of people experience significant tearing when cutting onions, and no matter how many you've chopped over the years, the reaction doesn't get easier. In this episode, Jen, Chris, and Matt unpack the full chemistry behind one of cooking's most universal frustrations. They exp...

Brain fog affects over a quarter of us — yet it isn't actually a medical diagnosis. So what's really happening inside your brain when thinking feels like wading through treacle? In this episode, Jen, Chris, and Matt unpack the real biological mechanisms behind brain fog — from neuroinflammation and a compromised blood-brain barrier to mitochondrial dysfunction and hormonal shifts. The team explain...

The ingredients on your supplement label that aren't the vitamin? They're not "fillers" and they're not there to cut corners. Most people don't know what these extra ingredients actually do, or why they're necessary. In this episode, Jen, Chris, and Matt tackle one of the most debated topics in the supplement world. With Chris's 30+ years as a formulation scientist, the team explains why supplemen...

Most of us have stood next to someone at the gym and wondered: why are they barely glistening while we look like we've run through a sprinkler? The answer is more fascinating than you'd expect — and it completely reframes what heavy sweating actually means. In this episode, Jen, Chris, and Matt unpack the biology behind sweat rate variation, from the hypothalamus acting as your body's built-in the...

Think going red during exercise means you're unfit? The science says otherwise. Exercise induced facial flushing has virtually no correlation with fitness level, and it might actually signal a more efficient cooling system. In this episode, Jen, Chris, and Matt explore why some people turn tomato red during a workout while others barely change colour. The answer lies in genetics, specifically in b...

Think you need to hit 10,000 steps every day? That target didn't come from a doctor or a clinical study. It came from a 1964 Japanese pedometer marketing campaign. In this episode, Jen, Chris, and Matt trace the surprising origin of the world's most famous fitness target and compare it with what modern research actually says about steps and health. A 2025 study published in The Lancet , analysing...

Less than 1% of the population genuinely needs less sleep. The rest of us claiming to be fine on four or five hours? We're most likely accumulating something called sleep debt, and our brains have become numb to the damage. In this episode, Jen, Chris, and Matt unpack the genetics of natural short sleepers, what your brain actually does while you're asleep, and why "adapting" to less sleep is one...

The "eight glasses of water a day" rule has been repeated so often it feels like biological law. But what if the whole thing started with a misunderstanding? In this episode, Jen, Chris, and Matt trace the eight-glasses myth back to a 1945 report that almost everyone misread, examine a landmark study of 5,600 people across 23 countries that revealed individual hydration needs can vary by up to 1,0...

Health advice is everywhere — but almost nobody explains why. Meet the team changing that. In this launch episode of So That's Why, hosts Jen, Chris, and Matt introduce the podcast that takes everyday health questions and actually answers them — with real research, proper context, and the kind of curiosity that makes you want to tell someone about it afterwards. The team behind Vegetology — a scie...