BITESIZE | The Most Powerful Daily Habit for Better Brain Health | Louisa Nicola #585

Summary

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Podcast Summary

Feel Better, Live More with Dr Rangan Chatterjee

Episode: BITESIZE | The Most Powerful Daily Habit for Better Brain Health | Louisa Nicola #585
Date: October 9, 2025
Guest: Louisa Nicola — Neurophysiologist & Brain Health Researcher
Main Theme:
How aerobic exercise and strength training can profoundly impact brain health, cognitive longevity, and even cancer prevention—plus practical, accessible strategies to get started at any age or ability.

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Key Discussion Points & Insights

The Brain-Boosting Power of Exercise

• Exercise Enhances Brain Structure & Function

  • Gray matter increase: Aerobic exercise can increase gray matter and enhance the brain’s neural networks, improving how we process information, make decisions, and even affecting personality and relationships.
    • “If you have a better functioning brain, more gray matter, more functional neural networks, you will perform better, think faster and live longer. It'll make you a better human.” — Louisa Nicola, [02:14]
  • Accessible benefits: Even minimal physical activity, like regular walking, can yield measurable increases in the size of critical brain areas such as the hippocampus (involved in memory).
    • Referenced: Study by Art Kramer showing hippocampal growth in inactive older adults after starting to walk regularly. [04:24]

• BDNF: The Brain’s Growth Factor

  • What is BDNF? Brain Derived Neurotrophic Factor is a hormone-like growth factor, produced especially during aerobic exercise, which travels to the brain and encourages new brain cells to grow, primarily in the hippocampus.
  • Why it matters: The hippocampus is the first area of the brain affected in Alzheimer’s; increasing its volume through exercise may offer protective effects.
    • “When it goes in there... it basically helps you grow new brain cells... The volume of the hippocampus grows, it increases, becomes more dense.” — Louisa Nicola, [03:17-04:24]

Debunking Myths Around Brain Decline

• Alzheimer’s Is NOT Inevitable
  • “Dementia is not part of the natural brain aging process.” — Louisa Nicola, [07:15]
  • Lifestyle factors—exercise, nutrition, sleep, and stress—shape brain health across the lifespan; Alzheimer’s pathology accumulates decades before diagnosis.

Exercise Guidelines & Practical Recommendations

• Minimum Effective Dose

  • Aerobic exercise: At least three hours per week at 65% maximum heart rate (“Zone 2”, i.e., conversational pace, a little out of breath but not struggling).
    • “Three hours per week of 65% of your maximum heart rate. That zone two zone.” — Louisa Nicola, [08:01]
  • Strength training: At least two sessions per week, ideally with compound movements (squats, lunges, bench press).
    • “At minimum two days a week... compound movements.” — Louisa Nicola, [22:04]
  • Intensity matters, but is individual: Even brisk walking or walking up hills can be sufficient, especially for beginners or older adults.
    • “Your brain doesn't know the difference between you running, cycling, or swimming. It just knows heart rate.” — Louisa Nicola, [12:01]

• Making It Accessible

  • Anything that raises your heart rate (cycling, walking, swimming, elliptical) counts.
  • “Gamifying” movement: Try to improve your walking distance/pace around your neighborhood (e.g., “walk to the highest-numbered house in 1 minute, then recover and try again”).
    • “You're gamifying it.” — Louisa Nicola, [17:39]
  • It's never too late or too early to start—everyone can adapt movement to their needs (e.g., wall sits for seniors).

Additional Benefits: Beyond Brain Health

• Exercise as Cancer Prevention

  • High-intensity intervals activate natural killer cells, reducing cancer risk by eliminating circulating tumor cells.
    • “You are able to inhibit 13 types of cancer through this type of training.” — Louisa Nicola, [13:21-14:01]

• Strength Training as a Foundation

  • Muscle mass declines exponentially after age 40; maintaining it is critical for energy, stability, and overall metabolic health.
  • Strength training releases myokines (muscle-derived proteins) supporting brain function, neural protection, and other organs—not just about aesthetics.
    • “Strength training releases another 100 of them [myokines]... For the brain, they help preserve the synapses, they help the other neurons survive, they help with the growth and proliferation of other neurons in the hippocampus.” — Louisa Nicola, [21:00]
  • Bodyweight exercises and home workouts are effective for those new to fitness.

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Notable Quotes & Memorable Moments

• “Exercise is medicine, and our muscles are like pharmacies.” — Louisa Nicola, [07:39]
• “The lifestyle factors we've sort of touched on, exercise, sleep, stress, and food... if you had to pick one... I don't think any other intervention can compare to exercise.” — Louisa Nicola, [07:23-07:39]
• “This actually helps you create more energy. When you're training in this zone, you're treating the mitochondria... to work better, to, to function better, to create more of itself so you can have more energy.” — Louisa Nicola, [08:29]
• “Find something that you love and something that's going to allow you to do this regularly without it being a real pain… Everyone's got something they can do if you find it.” — Dr Rangan Chatterjee, [19:00]
• “Don’t allow where you currently are to put you off getting started. Basically, if you take nothing else from this, just this idea that you can do something at home that literally is changing the structure and function of your brain.” — Dr Rangan Chatterjee, [23:58]

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Timestamps & Segment Highlights

• [02:14] Louisa Nicola explains how a healthy brain shapes our lives
• [03:17-04:24] The mechanism of BDNF and hippocampal growth
• [07:15] Dementia and brain aging – it’s not inevitable
• [08:01-08:15] Minimum aerobic exercise dose for brain health
• [12:01-12:31] Making cardio accessible for all ages
• [13:21-14:01] Maximally intense exercise and cancer protection
• [17:39] Gamifying fitness for beginners
• [22:04] Strength training recommendations

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Conclusion & Empowering Takeaways

• Consistent movement—at any age or starting point—can rejuvenate brain structure, slow aging, and reduce disease risk.
• Start small and adapt exercise routines to personal ability; every bit helps.
• Focus on what you can gain (energy, memory, longevity) rather than aesthetics.
• Strength and aerobic training both matter; each has profound, research-backed benefits for mind and body.

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This episode makes it clear: Move regularly for your brain, your body, and your long-term well-being—starting today, whatever your "today" looks like.

Transcript

[A]

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[B]

Absolutely. Everything your brain is responsible for, everything that you do. It is responsible for who you are, how you see, how you interpret information, how you sleep, how you eat, even down to the spouse that you choose. If you have a better functioning brain, more gray matter, more functional neural networks, you will perform better, think faster and live longer. It'll make you a better human.

[A]

And aerobic exercise, which isn't actually that difficult, is, is going to help you do that?

[B]

Absolutely.

[A]

And what are the mechanisms there? You mentioned bdnf.

[B]

BDNF is one. Yeah. Through exercise, through a specific pathway. It's the myokine pathway. When we, when we are engaging in aerobic activity, we get this expression, this release of a growth factor. It's called bdnf.

[A]

Okay, so what is bdnf and is it aerobic exercise that specifically increases it? Or. Or do other forms of exercise like resistance training and high intensity training also do It, Yeah.

[B]

So BDNF stands for brain derived neurotrophic factor. It is a growth factor for the brain, meaning that when it is expressed and you have to be, let's just say we're at that zone two, right. We're running, it gets expressed into the bloodstream. So it's a little hormone, if you will. And when it does, it goes through the bloodstream up into the brain. It does cross the blood brain barrier. But this is a really great thing. It gets in there and it goes into the hippocampus. The hippocampus is this seahorse shaped structure deep in the temporal lobes. And when it goes in there, it basically helps you grow new brain cells in that area. Now here's the phenomenal thing. That is the first structure of the brain to go during Alzheimer's disease. That is the part that holds your memories, short term memories. It's where memory formation occurs. And we've seen now through human studies that the hippocampal sub regions, the areas around the brain can also change in structure. But the volume of the hippocampus grows, it increases, becomes more dense.

[A]

I think I read some research a few years ago from Art Kramer and from recollection, it was people in their 60s, maybe in their 70s. And just from walking, not that much every week. You may know the study to hand. I think a year later the hippocampus looks bigger.

[B]

Yes. And that's because the starting point, they were very inactive.

[A]

Okay.

[B]

Yes.

[A]

So that's really interesting. So if you're really inactive, anything you do is going to make a difference.

[B]

That's the great point.

[A]

Yes, that's really empowering for people because you don't want to. You know, when we start talking about zone 2s and zone fives and high intensity and VO2 maxes and I want to talk about all those things. I think some people who don't move that much are like, yeah, I mean that all sounds great, but I don't know where to start. Like I don't really move much at the moment. So I think we want to leave that message at least that hey, it doesn't matter where you are, just start moving a bit more.

[B]

Even if that involves you walking for 10 minutes a day. You know what's really great? If you live around hills, just walk for 10 minutes a day, maybe get on one hill, just get out and just do it easy. Because when you do, you will feel the benefits. By the way, bdnf, when it is expressed, it doesn't just help with hippocampal volume. We get other things as well. It helps with the expression of different neurochemicals that are involved in mood. We know that there is a direct correlation between depression and exercise. Why is that? Maybe it's because you're changing the structure of your brain through physical activity.

[A]

And this is one of the things I love the most about your message. It's very empowering. The message you're putting out there to the world is very much about saying to people, look, there is so much that you can be doing right now, no matter how old you are, that's absolutely gonna make a difference in the future.

[B]

100%. We think about Alzheimer's disease as this one point in our life in our 70s that we're diagnosed with. When you are diagnosed in your 70s or in your 80s, that disease has been accumulating since your 20s, your 30s, and your 40s. Right now, Alzheimer's disease, 55 million people worldwide have this disease. That number is going to triple by the year 2050. In the UK, Alzheimer's disease is the second leading cause of death and the first leading cause of death among women. Now, two out of three Alzheimer's disease cases globally are female. So that's something to consider.

[A]

I think there's a common belief in society that our brains are going to decline as we get older. I think many people believe that Alzheimer's is an inevitable consequence of the aging brain, but it's simply not the case, is it?

[B]

Absolutely not. And I always tell people that dementia is not part of the natural brain aging process.

[A]

The lifestyle factors we've sort of touched on, exercise, sleep, stress, and food, they're all important. Yeah, but if you had to pick one for people to focus on, is there one that comes to the surface for you?

[B]

I don't think any other intervention can compare to exercise. I believe that exercise is the panacea for health. Exercise is medicine, and our muscles are like pharmacies.

[A]

So your recommendation for aerobic exercise is what? Like, for optimum brain health, at minimum.

[B]

Three hours per week of 65% of your maximum heart rate. That zone two zone.

[A]

Okay, so conversational pace, Little bit out of breath, but not too out of breath. Three hours. Yeah. Okay, fine.

[B]

So that's minimum.

[A]

Minimum. So at least half an hour a day.

[B]

Yeah.

[A]

Which I think is pretty reasonable. And I do you want to make things accessible to people. At the same time, you want to be honest with them and sort of go, listen, you have to move your body.

[B]

And for the people who are like, but I don't have enough energy. This actually helps you create more energy. When you're training in this zone, you're treating the mitochondria, which is the powerhouse of our soul, where we produce our energy to work better, to, to function better, to create more of itself so you can have more energy.

[A]

What do you wish everyone knew about exercise and the brain?

[B]

I wish everybody would exercise for their brain health and for health outcomes and longevity rather than aesthetics. In my world, people are. But that's a mere, probably 10% of the population. The physical activity guidelines globally state that we should be exercising around 150 minutes to 300 minutes per week. And that's moderate to vigorous physical activity.

[A]

Which means what?

[B]

Exercising at around 65% to 75% of our maximum heart rate.

[A]

Are you able to give some examples of activities that might fall into that category?

[B]

Yeah. So imagine you are running up a flight of stairs and you are going full force. And the last step is when your heart rate, you feel like it's going to come out of your chest, you know you've reached most likely your maximum heart rate. Let's just say that's 200.

[A]

Okay.

[B]

Okay. You want to be working. I mean that would be very high. That's a young, young person. Let's just say 100 then, just for argument's sake. That means that we want you working out at 65% of that 100 beat. That is your maximum heart rate. So we want you to be working out for 150 minutes at 65% of your 100, so 65 beats per minute.

[A]

Okay. So that's going to depend on who we are or what our maximum heart rate is. But essentially we're talking about things like a pretty fast walk.

[B]

Fast walk? Yeah, fast paced walk, a jog, an easy jog where you can, where you can hold a conversation. But you are, you feel like you're working out at the same time.

[A]

Do you agree with those physical activity guidelines first of all, or do you think they are conservative?

[B]

They're conservative. And it's around 80% people who are not meeting the physical activity guidelines in.

[A]

What countries like America and the uk?

[B]

Yes, Correct.

[A]

Yeah. Okay. And we know that physical inactivity is one of the leading causes of premature death globally. Right. So that's pretty well established. So I know, cause I've spoken to people in public health over the years that sometimes public health guidance is given not necessarily because it's optimum, but because it's like, well, if we push it much beyond this, no one's gonna do It.

[B]

Yes.

[A]

Right. And so what is enough in your view, based upon the research that you've seen?

[B]

Yeah, that also people don't know. How many times am I meant to be doing weight training? How many times am I meant to be doing aerobic training? So they're just compiling it all together. So let's break it apart. Your aerobic training should be made up of at minimum three hours a week. So aerobic training are things like your long distance running, cycling, anything where you're able to move at around that 65% of maximum heart rate.

[A]

So you don't feel as though you're crushing it or you're pushing hard.

[B]

It's quite, you know, aerobic, it's easy, it's your long slow distance running, I call it.

[A]

So what about someone who doesn't run?

[B]

Your brain doesn't know the difference between you running, cycling or swimming. It just knows heart rate. So get on a bike, an elliptical trainer at the gym, anything that is, that it's in the cardio zone of the gym. Anything that's just going to get you into that steady state of 65% to.

[A]

75% and you don't have to push yourself hard here. I think that's important. Right, so you should be able to have a conversation whilst doing this.

[B]

Yes. And at the end of every sentence you should be like, you know, you have to take a breath.

[A]

Okay. So you're lightly exerting yourself, but your heart rate is certainly elevated compared to when you're just sitting down.

[B]

Yes. Right. When we talk about zones, we talk training zones. Zone one, we are set. Entry that zone two is that next level up. 65% of maximum heart rate. Everyone needs to understand it's very individualized. Your zone two is different from my zone two. If I am not very metabolically fit, my zone two might be fast paced walking. We've got zone three. And then when you're in that zone four, I call that the death zone. That's when you are working so hard running up those stairs to your maximum.

[A]

The death zone.

[B]

Yes, the death zone. When we are training in that zone four or zone five.

[A]

So this is more people might be more intense. High intensity.

[B]

High intensity. Right. So that's the sprints, that's when you're doing running up those stairs where you're really like struggling to get air. Many things are happening in this zone. You're doing a lot for cancer outcomes and for brain health outcomes. So remember when you're training at that zone, you're getting a massive shunt of blood to your brain and to the rest of your body. During that process, during the sheer force and the shunting of the blood, you are able to to have an effect on 13 types of cancer. You are able to inhibit 13 types of cancer through this type of training.

[A]

Wow.

[B]

Yeah. And the way that it does that is there's three ways. The first one is when you exercise in this zone, you are increasing your production of natural killer cells. And these natural killer cells, they're a lymphocyte, but without getting too much into it, these natural killer cells are able to locate a circulating tumor. Circulating tumor cells and kill them. These circulating tumour cells are abundant through our body. If we have a tumor, let's just say you are diagnosed with stage one cancer, which is the best type to get diagnosed with. There is a tumor that has formed somewhere in your body. What happens is that tumour, some of the cells tend to break off and we call these circulating tumor cells and they roam around through the body to lodge and create another tumor that we then move into metastases during that process. These circulating tumor cells through the body can actually be ameliorated through the sheer force of this blood flow via that maximal aerobic exercise.

[A]

Wow.

[B]

Yeah.

[A]

So it's helpful for your brain function as you age, but it's also helpful for reducing your risk of getting cancer.

[B]

Absolutely.

[A]

Okay. There's going to be some people listening who go, well, I'm no longer physically capable enough to run up a flight of stairs. You are at your age and your fitness level. I am. But some older listeners may go, well, hold on a minute, I can't do that or I feel that would injure me.

[B]

Yes.

[A]

These heart rates and these zones are all relative to your own baseline. Right. So what someone in their 30s might do might be different from someone who's 70.

[B]

Yes.

[A]

Yeah.

[B]

And so what I do with my parents is I get them to walk up a hill. We've got this steep hill back at my home that I grew up in, and once a week they have to walk up and down that for 20 minutes. And let me tell you, they are getting to their maximum. I even get to my maximum if I'm jogging. It is really steep. They have to take some breaks as they're going up. They're not running, they are just walking up a hill.

[A]

I think walking up hills is one of the very best forms of movement. It really is.

[B]

And look, it only needs to be done 20 minutes a week.

[A]

So this kind of training, in terms of your brain prescription, you're saying three hours aerobic, 20 minutes of this form of exercise. Okay. I mean, one of my favorite recommendations to patients over the years regarding intensity, depending on their age would be okay, where you live, okay, walk around the block as a warm up and then if you're back at your house, see in one minute, walk as fast as you can and see what number door you get to. Okay. When you get there, walk back relaxed and then you come back. Hopefully by the time you're back to your house, you're feeling really relaxed and you've recovered. And then go again as fast as you can and see what number house you can get to. And maybe do that four or five times. And then what I really liked about it, it was a very simple and accessible way for people to start playing around with intensity and using their inner competitiveness to go, oh, you know, I got to number 24 yesterday. After two weeks of doing it, I could get to number 28.

[B]

So you're gamifying it.

[A]

Exactly. And I found for people who maybe get put off by going to the gym or maybe hill walking, seems like something that they can't do. I found that quite useful. So you're saying that exercise is probably the number one thing that people can do and focus on to protect their brains long term?

[B]

Yes.

[A]

One of the mechanisms by which exercise does all this magic in our bodies and frankly our brains is through bdnf, brain derived neurotrophic factor. And you're saying that we need to do a minimum really of 3 hours aerobic exercise a week. Okay. And where have these numbers come from? This three hours of aerobic, the 20 minutes of intense training like this is all coming from the research that you've studied, right?

[B]

Absolutely. Everything I'm talking about I've researched thoroughly. I think my last paper there was about 1500-2000 references and that's what I do daily. So they're very gold standard when we come to academic research.

[A]

Yeah. One of the biggest things I've changed in my life over the past two years is my love is a physical activity.

[B]

You have to love it.

[A]

Yeah. You've got to find something that you love and something that's going to allow you to do this regularly without it being a real pain. And everyone's got something they can do if you find it. I guess for me, I've realized that when you really dive into the research on exercise and longevity and brain health and cancer and all these things, it's very hard not to come away with the conclusion that despite the common narrative that society today often puts out, which is, you know, take it easy as you get older, I kind of feel that's problematic. I feel the older you get, the more you have to be thinking about moving your body and not allowing yourself to get sedentary. So what does that mean for me? I now, I would say 95% of the time, I'm walking for at least an hour a day.

[B]

Yes.

[A]

Like, it's just something I've decided. I made a decision in my brain, a conscious decision, a couple of years ago, saying no, wrong. And listen, if you want good brain health, good heart health, if you want to be functioning as well as you can as you get older, if you want to be the best dad, the best husband, the best son, you have to move your body. You cannot let other things get in the way of that. Am I fortunate to have some autonomy in my life to do this? Yes, I am. But nonetheless, with the autonomy, I've made that choice. And that's kind of like a minimum for me. I do other things as well, but one hour's walk is kind of a minimum for me.

[B]

Yeah.

[A]

So how important is strength training?

[B]

Oh, my gosh. Strength training, I believe, is probably fundamentally the most important part of exercise.

[A]

Really?

[B]

Many reasons. One, you're increasing your muscle mass. We know that at the age of 40, we get a decline exponentially in strength and mass. Think about muscle as your reserves. Okay. Muscle is an endocrine organ. It stores a lot of our mitochondria, where we produce all of our energy. It helps us and stabilizes us as we get older. But it's the journey of building the muscle that is the most important, because when we are strength training, we are releasing and expressing a whole host of myokines. Now, we mentioned bdnf, that's a myokine. But oh, my gosh. Strength training releases another 100 of them. Myokines are muscle based proteins that when they go into different organs in the body, the brain, the liver, the pancreas, they have positive effects. So for the brain, they help preserve the synapses, they help the other neurons survive, they help with the growth and proliferation of other neurons in the hippocampus. So they're doing the same thing as bdnf, but they're doing even more than that. BDNF just goes into the brain, but these myokines can actually go elsewhere.

[A]

Do you have a specific recommendation for resistance training?

[B]

So in the paper that I authored alongside our friend Dr. Tommy Wood, I.

[A]

Think Gabrielle Lima was On that as well.

[B]

Gab was on it too. Yeah. So this was at minimum two days a week. And this is compound movements.

[A]

What does that mean for people who've never heard that term?

[B]

Yeah. So that's just squats. Instead of doing the designer aesthetics. Okay. You want to be doing things that move as many muscle groups as possible per exercise.

[A]

So not the bicep curl while looking.

[B]

In the mirror curl. No, no. So you want to be doing squats, bench press, walking, lunges are great. Anytime you can really work the lower part of your body as well. Just due to vector size of your. Of your quads, for example, you're just increasing your, your gray matter. Now. Let's talk about somebody who doesn't even. And they've never been into a gym before. You can still get the same benefits. We have a close family friend and she was. She's kind of like a grandmother to me. She's 98 years old. Cognitively she is firing. She's unbelievable. She's maintained exercise and dancing her entire life and social interactions. Right. If I was to tell her to increase her muscle mass, we just have to get her to wall sit. She can increase her muscle size in her legs and get massive gains. If she was just to wall sit for me, that wouldn't work because I have stronger legs and I'm much younger than her. What I mean by that is if you are completely set entering, you want to start lifting weights, you don't have to go into the gym and pound these weights. As I'm saying, you can start with calisthenics which is just body weight movements. Start with doing some pushups. You can go onto YouTube and just type in beginner workouts for 50 year old females. I set them up for my mom all the time when she tells me she doesn't know what to do. And that's how you can start.

[A]

Yeah. So don't allow where you currently are to put you off getting started. Basically if you take nothing else from this, just this idea that you can do something at home that literally is changing the structure and function of your brain.

[B]

Yes.

[A]

That's pretty empowering.

[B]

That is the most beautiful thing about exercise.

[A]

Hope you enjoyed that bite sized clip. Hope you have a wonderful weekend. And I'll be back next week with my long form conversational Wednesday and the latest episode episode of Bite Science next Friday.