Brown fat, testing the obesity paradox, and baseball's elbow surgery epidemic

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Health Report 28 min 2 speakers 8 chapters transcribed 4 days ago

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What is brown fat and how does it affect metabolism?

Dr. Norman Swan 0:00

Hello and welcome to this week's Health Report with me, Norman Swann. Today, when being thin means you're at higher risk than being obese. How sophisticated sports surgery, once the domain of elite athletes, it's finding its way into high school sport, at least in the United States, and probably here too.

David Altchek 0:19

You know, throwing appears to be I hate to say an unnatural position for the elbow. Throwing hard is an extremely unnatural position, and that is markedly increasing the incidence of this injury in young athletes.

Dr. Norman Swan 0:30

Well, there's also been some research in the last few days into brown fat. You know that stuff that's supposed to make you thin? Well, it does a lot of other things as well, perhaps. And that's been the research interest of Doctor Paul Lee, who's an endocrinologist at the Garvin Institute. Welcome to the Health Report, Paul.

Paul Lee 0:45

Good afternoon. Thank you for the invitation.

Dr. Norman Swan 0:46

Well, f let's just start at the beginning, 'cause you've just published these fascinating findings on brown fat. What is brown fat?

Paul Lee 0:52

Brown fat is an amazing tissue. So you can see it as a heat generator. Heat generator. Exactly. Do we all have brown fat? You clearly have got brown fat, you're much thinner than I am. I mean Well, I think everyone has brown fat. The difference is some people have more and some have less. Tell me

Dr. Norman Swan 1:07

about the study that you did. What did we know bef about brown fat before you did your study?

Paul Lee 1:11

I guess we are all familiar with white fat. That's the ordinary kind of fat that we have in the body. And when we have too much white fat, we develop obesity, diabetes, etc. In contrast, brown fat is actually a tissue which burns sugar and fat. And our previous study shows that individuals with more brown fat are leaner and have lower sugar levels.

Dr. Norman Swan 1:32

And brown fat is just part of your genetic structure or what? What causes the induction of brown fat? We know that babies have a lot, newborn babies

Paul Lee 1:40

have. Babies and small animals. So the most well known function of brown fat is to keep us warm and it essentially burns sugar and fat to generate heat.

Dr. Norman Swan 1:49

And so it's a survival mechanism and

Paul Lee 1:52

so small animals and infants because they can't shiver rely on brown fat to keep them warm. So how come you've got more than me? Because I live a brown fat life. Seriously, so it's so it's

Dr. Norman Swan 2:03

environmentally induced.

Paul Lee 2:05

Well, one of the most uh well known stimulation of

Dr. Norman Swan 2:07

brown father. Tell me what you had for breakfast, and Paul told me he had a glass of milk. So this is it, you know, anyway, we'll

Paul Lee 2:18

And it is cold because the cold temperature stimulates brown fat.

Dr. Norman Swan 2:21

Right. So Australians don't have a lot of brown.

Paul Lee 2:23

Brown fat then? It depends on how much cold you expose yourself to. Okay. So it's environmentally induced there's obviously a genetic story in there as well. Yes. I we we know very little about brown fat in adults, but as far as we know, mild cold exposure would stimulate the growth of brown fat. What did you do in this study? In this study, we try to understand the relationship between brown fat and sugar burning during daily living. So we measured brown fat activity and sugar levels in volunteers to understand the relationship. And

Dr. Norman Swan 2:51

what did you find?

Paul Lee 2:52

We use some tiny temperature probes placed above the collarbone of these volunteers because that's where brown fat is most abundantly found. So it's around your shoulder region. Exactly. And essentially, when brown fat activates, the overlying skin temperature warms up. So we can track brown fat activity continuously. And we identify this brown fat biorhythm in these volunteers, in which the brown fat activity and sugar levels track very. Very closely. In what way? So what's interesting is with each surge in brown fat activity, sugar levels drops. In other words, brown fat somehow is able to sort of put a cap on sugar level fluctuations. And so were you giving these people a sugar drink or what were you were you inducing it through?

Paul Lee 3:33

Were you inducing it through Mr. Neel? So they're allowed to live their ordinary life and do their usual activities. And what is interesting is no matter what they are doing, the brown fat activity