Explore every episode of the podcast So That's Why

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 blood vessel density and reactivity. The team breaks down what's really happening under your skin, why people with pronounced flushing often have better thermal regulation, and what you can actually do about it if it bothers you.

In this episode:

1. 00:00 Introduction
2. 01:04 Why fitness has nothing to do with it
3. 02:47 Blood vessel density and reactivity explained
4. 04:06 Why going red might actually be an advantage
5. 05:39 Ethnicity, gender and age differences
6. 08:09 What actually helps reduce flushing
7. 11:41 The human mood ring connection
8. 13:04 So that's why your face turns red

It's Not About Fitness. It's About Your DNA.

[01:04]

The assumption that you'll stop going red when you get fitter is one of the most persistent myths in exercise culture. Research shows that flushing intensity has virtually no correlation with cardiovascular fitness, effort level, or how out of shape someone is.

As Chris puts it: "It's got virtually nothing to do with fitness level and everything to do with how your cooling system is programmed."

Despite this, the myth has real consequences. Studies have shown that people with pronounced exercise flushing are around 40% more likely to avoid group fitness classes, often choosing to exercise alone or during quieter gym times. That's a significant number of people changing their health routines because of something they can't actually control.

"My fitness has improved loads over the past five years especially, and I still turn bright red." — JenBlood Vessel Density and Reactivity

[02:47]

So what is actually causing the variation? It comes down to two genetically determined factors: blood vessel density and blood vessel reactivity.

1. Blood vessel density refers to the number of blood vessels packed into the skin of the face. This varies greatly from person to person. More vessels near the surface means more visible blood flow when they dilate.
2. Blood vessel reactivity is how quickly those vessels respond to triggers like heat and rising core temperature. Research conducted in Australia found that some people's facial blood vessels react to increases as small as a third of a degree Celsius.

For context, core body temperature during exercise might rise by one to two degrees overall. For highly reactive individuals, their facial blood vessels are already responding before they've barely warmed up.

"In some people it could be responses that kick in when your body temperature increases by just a third of a degree Celsius." — ChrisWhy Going Red Might Be a Superpower

[04:06]

People with high facial vascular reactivity tend to have better overall thermal regulation. Their bodies get ahead of the heat problem before it becomes serious, which means better core temperature maintenance and reduced overheating risk during prolonged activity.

Chris notes that "pronounced facial flushing often correlates with better performance in hot temperatures." Athletes with higher facial vascular reactivity appear to maintain better performance when training in the heat.

The difference comes down to how the body distributes its cooling effort. Some people have distributed thermoregulation, spreading heat dissipation evenly across their body. Others concentrate the response in the face. Same system, same outcome, different display. From a physiological perspective, concentrated facial flushing has no trade offs.

People with this responsive vascular system also tend to blush more easily during emotional stress and react more strongly to spicy foods and temperature changes.

"Those of us who turn red during exercise, basically we're human mood rings." — Matt

The same genetic programming also supports better long term cardiovascular adaptation. People with responsive vascular systems often see resting heart rate and blood pressure reductions faster with training.

"The same genetic programming that's making us look like tomatoes is actually supporting the long-term cardiovascular adaptation." — JenWhat Actually Helps (and What Makes It Worse)

[08:09]

Since flushing is genetic, it can't be eliminated entirely. But the episode covers several evidence backed ways to reduce its intensity:

1. Pre cooling — Applying cool, damp cloths to the wrists and temples for two to three minutes before exercise can reduce facial flushing intensity by about a quarter. These pressure points have blood vessels close to the surface that connect directly to facial capillaries.
2. Hydration timing — A glass of cool water about 20 minutes before exercise helps maintain better temperature regulation. The body needs time to distribute that fluid before heat stress begins.
3. Clothing choices — Light coloured, moisture wicking fabrics reduce overall heat load. The neck area is particularly important, as it contains major blood vessels that supply the face.
4. Avoid alcohol within 24 hours of intense exercise, as it dilates blood vessels and makes flushing more pronounced. Very hot showers immediately after exercise can also prolong the response.

For most people, exercise flushing is completely harmless. If it's accompanied by dizziness, nausea, or confusion, or doesn't resolve within 30 minutes, that's worth checking as it could indicate heat exhaustion.

"It's not a sign of being out of shape. It's a sign that your temperature control system is working exactly as designed." — JenAbout 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.

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 data from over 160,000 adults globally, found that the real health benefits of walking kick in much earlier than most people think, and that the ideal step count depends on your age, your health, and your lifestyle.

Key points covered in this episode:

1. 00:00 Introduction
2. 01:43 The huge health benefits of walking
3. 03:19 The 1964 Tokyo Olympics marketing origin
4. 05:10 What researchers actually found decades later
5. 06:38 Why age changes your ideal step count
6. 08:42 Why not all steps are created equal
7. 11:06 What your personal target should be
8. 15:29 Weekend warriors and other forms of exercise
9. 16:28 How steps connect to sleep and mental health
10. 18:21 So that's why we chase 10,000 steps

The 10,000-Step Target Was Born From Marketing, Not Medicine

In 1964, a Japanese company developed one of the first commercial pedometers and named it the Manpo-kei, meaning "10,000 step meter." The number was chosen partly because of its cultural significance in Japan as a symbol of long life, and partly because the Japanese character for 10,000 looks like a person walking.

There was some science in the mix. Dr Yoshiro Hatano at Kyushu University calculated that going from 4,000 to 10,000 steps would burn roughly 500 extra calories per day. But as Jen puts it, "It was basically one guy with a calculator being like, yeah, 10,000 sounds good."

"Our entire fitness culture is based on what a Japanese character looked like. It feels a little bit like deciding to eat eight meals a day because that's the shape of a snowman." — MattThe Science Says You Probably Need Fewer Steps Than You Think

When researchers eventually studied the relationship between step counts and health, they found a more nuanced picture. A major study of 160,000 older women found that just 4,400 steps per day was associated with a 40% reduction in mortality risk compared to 2,000 steps. Benefits plateaued at approximately 7,500 steps.

The Lancet study reinforced this, showing that people walking at least 7,000 steps per day had a 25% reduction in cardiovascular disease risk, 38% lower chance of dementia, and 22% reduction in depression.

The health gains follow a curve that rises steeply at first, then flattens. The biggest improvements come from moving out of a sedentary lifestyle, not from chasing the highest possible number.

"10,000 steps as a daily target's not wrong. It's just not universally right either." — ChrisYour Ideal Step Count Depends on Who You Are

Optimal step counts vary dramatically based on age, health status, height, and lifestyle. For adults under 60, benefits plateau at 8,000 to 10,000 steps. For those over 60, maximum benefits are often reached at 6,000 to 8,000. People with chronic conditions can see meaningful improvements from just 2,000 to 3,000 additional steps per day.

Intensity matters too. A 2024 study found that 15 minutes of brisk walking daily was associated with a nearly 20% decrease in mortality risk. The same number of steps at a slower pace doesn't deliver the same benefit.

"The best exercise you should do is one that you will actually do." — MattSteps Connect to Sleep, Mood, and the Bigger Health Picture

Higher daily step counts are directly linked to better sleep quality, less time falling asleep, and more deep sleep. The mental health connection is equally striking, with a 22% reduction in depression risk at 7,000 steps compared to 2,000.

"Your movement affects your sleep and your sleep affects your mood and that affects your motivation. It all works together." — MattAbout 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 judgement — just genuine curiosity and proper research.

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 of the biggest myths in sleep science.

What You'll Learn

1. Why less than 1% of people carry genuine short-sleep genetics
2. What happens to your brain after just one night of poor sleep
3. The waste-removal system your brain runs every night
4. Why you can't train yourself to need less sleep
5. How age, circadian rhythms, and environment shape your sleep needs
6. Practical ways to figure out what your body actually needs

Key Timestamps

00:00 - Introduction

01:08 - Genetic mutations and natural short sleepers

04:09 - Your brain takes out the trash while you sleep

05:25 - Sleep stages and where the real recovery happens

07:21 - The myth of adapting to less sleep

08:20 - Age, teenagers, and biphasic sleep history

11:33 - Warning signs of chronic sleep debt

13:45 - Circadian rhythms and sleep environment

15:06 - Can supplements help with sleep quality?

16:31 - Why sleep connects to everything else

19:19 - So that's why some people need less sleep

The Genetics of Short Sleep

In 2009, researchers at the University of California, San Francisco, discovered the first family with natural short sleep syndrome. A mother and daughter required just 6.25 hours of sleep per night, compared to 8.06 hours for other family members. The difference was a mutation in the DEC2 gene, which affects the molecular clock in the brain.

As Chris explains: "These people with this ability, this mutation, they don't just cope with less sleep, they actually need less while maintaining the same perfect cognitive function."

Since then, scientists have found other gene mutations with similar effects. But these natural short sleepers remain extraordinarily rare.

"They've won the genetic lottery, except instead of millions, they won the ability to function on less sleep." — MattWhat One Night of Bad Sleep Does to Your Brain

Research involving over 5,000 people found that after just one night of four to six hours of sleep, reaction time slows by 50%, working memory drops by 40%, and the ability to form new memories decreases by roughly 40%.

The unsettling part? People don't realise how impaired they are.

"Your brain adapts to feeling tired, so you think you're functioning normally when you are actually functioning like you've had several drinks." — Jen

That adaptation has a name: sleep debt. And it accumulates quietly.

Your Brain's Nightly Maintenance Routine

During deep sleep, brain cells physically shrink by 60%, opening up space to flush out waste products accumulated during the day, including proteins associated with Alzheimer's disease. An all-nighter essentially cancels this process entirely.

"When someone says they're too busy to sleep, they're saying they're too busy to let their brain take out the trash." — Matt

REM sleep transfers information from temporary storage to permanent storage in the cortex. Miss it, and long-term memory formation suffers.

The Myth of Adapting to Less Sleep

Multiple studies show that while you might feel less tired over time, performance continues to deteriorate beneath the surface.

"It's a bit like altitude sickness. You stop feeling nauseous, but your blood oxygen levels are still dangerously low." — Matt

Warning signs of chronic sleep debt include needing caffeine to function, falling asleep within minutes of lying down, sleeping significantly longer on weekends, and feeling groggy upon waking.

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.

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 1,000%, and explain why your body's built-in thirst system is far more reliable than most of us give it credit for. Along the way, the team tackles some surprising findings, including why milk is more hydrating than water, why coffee counts towards your fluid intake, and why over-hydrating can actually do more harm than good.

In this episode:

1. 00:00 — Introduction
2. 01:21 — Where the eight-glasses rule actually came from
3. 05:00 — The isotope tracking study that changed the picture
4. 06:28 — How your body's hydration system really works
5. 08:28 — How needs vary by person, lifestyle, and life stage
6. 11:28 — Electrolytes, milk, and what actually hydrates
7. 12:58 — The simplest way to check your hydration
8. 16:00 — When over-managing hydration backfires

The 1945 Recommendation That Got Lost in Translation

[01:21]

The original "eight glasses a day" idea traces back to a report from the US Food and Nutrition Board in 1945. It recommended around 2.5 litres of total fluid per day, but that included fluids from food, coffee, tea, and all other beverages. Somewhere along the way, the crucial word "total" got dropped, and the recommendation became "drink eight glasses of plain water."

As Chris explains: "It's a multi-decade misunderstanding that became so deeply embedded in everything that we do, it's almost overridden our body's natural programming."

A well-known kidney specialist, Dr Heinz Valtin, spent years trying to find scientific proof for the eight-glasses rule. His conclusion? There was no evidence that every person needs to drink at least eight glasses a day.

The result: many of us have been over-hydrating by 30 to 40% more than our bodies actually need.

Your Body Has a Built-In Hydration System

[06:28]

The body manages hydration through sensors in the brain that effectively taste blood for salt concentration. If the blood is too salty, they trigger the sensation of thirst. If it's too dilute, they send signals to the kidneys to flush out the excess.

"Your body detects when you need food. It detects when you need to sleep, when you need to go to the bathroom. So why would water detection be uniquely unreliable?" — Chris

There's a widely repeated claim that by the time you feel thirsty, you're already dehydrated. Chris addresses this directly: that idea comes from studies on athletes in extreme conditions or elderly people with impaired thirst mechanisms. For most healthy people, thirst is a perfectly reliable indicator.

Hydration Needs Vary By Up to 1,000%

[05:00]

Researchers tracked 5,600 participants across 23 countries using isotope tracking, a technique Chris describes as "giving water molecules little name tags so we can follow them around the body." The findings showed enormous variation: some people need just one litre of water a day, while others need more than ten.

Young adult males needed roughly 1.5 to 1.8 litres of drinking water a day. For females, slightly less, around 1.3 to 1.4 litres. Crucially, that includes all fluids, not just water.

As Jen puts it: "Everyone thinking they need exactly eight glasses of water is like everyone trying to wear the same size shoes."

Factors that shift individual needs include age, activity level, climate, body size, genetics, and even personality traits. People with higher anxiety tend to have higher water turnover, linked to increased breathing and heart rates.

What Actually Counts Towards Hydration

[11:28]

One of the episode's most reassuring findings: coffee, tea, and other beverages all contribute to hydration. Although caffeine has a mild diuretic effect, the water content in coffee more than compensates for it.

The team also reveals that milk is actually more hydrating than water, retaining fluid about 50% better thanks to its sodium and protein content. And food accounts for 20 to 30% of daily fluid intake — cucumbers are 96% water, tomatoes 95%, and oranges around 86%.

"Your body knows how to manage hydration. Trust your thirst, check your urine colour, save that mental energy for something more pressing." — ChrisAbout 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.

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 science-driven supplement company — explain why they started the show, what listeners can expect from each 20-minute episode, and why understanding the mechanism behind health advice matters more than memorising rules. Plus, a first look at what's coming in Episode 1: the truth about that "eight glasses of water a day" recommendation.

Key Points:

1. 00:00 — Opening and host introductions
2. 01:00 — Why health advice rarely explains the "why"
3. 02:00 — The Vegetology connection
4. 02:30 — What to expect from every episode
5. 03:00 — Teaser for Episode 1 on hydration myths
6. 04:00 — Who the podcast is for
7. 05:00 — How to subscribe and get involved

The Gap Between Health Rules and Understanding Why They Exist

(00:00)

Most health content tells people what to do without explaining why it works. Drink this much water. Walk this many steps. Sleep this many hours. The rules pile up, they often contradict each other, and there's rarely any explanation of the biology underneath.

"When you understand the why behind health advice — whether it's about your body, your nutrition, your fitness, or just the way we live our lives — you can actually make decisions that work for your life, not just follow rules that may or may not apply to you." — Matt

So That's Why was built to fill that gap. Not with more instructions, but with genuine understanding of how the body works and what the research actually says.

Meet the Team Behind the Microphones

(01:00)

The show is hosted by three people who also run Vegetology, a nutritional supplement company built on science rather than marketing trends.

1. Jen holds a PhD in biochemistry and molecular biology. She asks the questions the listener is already thinking — and because she understands the science deeply, her follow-ups go exactly where they need to.
2. Chris is a formulation scientist with over 30 years of experience. He brings the research citations, explains the mechanisms, and reaches for analogies that make complex biology feel intuitive.
3. Matt comes from an e-commerce and nutrition background. He bridges the science to everyday life, checking that the explanations actually make sense for real people.

"Think of us as your science-curious friends who happen to have the backgrounds to dig into research and translate it into something actually useful." — Matt"You basically mean we are geeks." — ChrisWhat Makes This Show Different

(02:30)

Every episode runs about 20 minutes and follows a consistent format: one question, usually starting with "Why do we...?", answered with real research, named institutions, and genuine numbers — not vague claims.

The show sits in what Jen describes as "that sweet spot between too technical to understand and so simplified it's not actually true anymore."

Key commitments:

1. Real research with specific studies and institutions named
2. Analogies that make complex biology click
3. Acknowledgement that science applies differently to different people
4. No prescriptions, no guilt, no fear-based messaging
5. Empowerment through understanding, not rules

"We're the people who read the full study, not just the headline." — MattComing Next — The Eight Glasses of Water Myth

(03:00)

The first proper episode tackles a piece of health advice that almost everyone has absorbed as fact: the idea that you need to drink eight glasses of water every day.

"There's an interesting background to where that specific number came from and how research doesn't necessarily agree with it at all." — Chris

The answer involves a misunderstood recommendation from 1945, individual variables most people never consider, and the role of water content from food — all of which got lost somewhere along the way.

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.