AMA #22: Losing fat and gaining fat: the lessons of fat flux

**Peter Attia** (0:11)
Hey, everyone, welcome to a sneak peek, Ask Me Anything, or AMA episode of the Drive podcast. I'm your host, Peter Attia. At the end of this short episode, I'll explain how you can access the AMA episodes in full, along with a ton of other membership benefits we've created. Or you can learn more now by going to peterattiamd.com forward slash subscribe. So without further delay, here's today's sneak peek of the Ask Me Anything episode.
Hey, everyone. Welcome to Ask Me Anything number 22, AMA number 22 I'm once again joined by Bob Kaplan. In today's episode, we discuss fat flux, which is really technical speak for how fat enters and exits a fat cell, which is exactly what determines how big a fat cell is, and how big a fat cell is, is what determines how much fat a person is carrying. So anytime you hear somebody say, I want to lose weight, what they're really saying is I want to lose fat mass. And what that really means is I want my fat cells to be smaller.
So if you want to understand how that works, this is an episode that's probably for you. Again, we go into it in a staggering amount of detail.
This is accompanied by some slides. So if you're watching this on video, you'll see those. If not, you'll see them in the show notes. I recommend checking that out. Also, this video will be available in its entirety to the subscribers in the show notes section. If you're not a subscriber, but you still want to see part of the video, it's going to be on YouTube, on our YouTube channel. So without further delay, I hope you enjoy AMA number 22

**Bob Kaplan** (1:50)
Are you ready for another AMA?

**Peter Attia** (1:52)
I am. I see the agenda, and I'm going to share my concern up front, which is I think it's a little ambitious. We're going to attempt to cover two topics frankly, each of which I think is their own AMA. So if by the time we get through this, it's so big that it is two AMAs, the person listening will say, what were they talking about? They just covered one topic. So as it stands at this moment, we're going to attempt to get through both everything that has to do with fat oxidation and fat flux and all these things you're going to explain in a second, and we're even going to try to tackle the entire topic of nicotine.
So let's see if we can do it.

**Bob Kaplan** (2:34)
I feel like ambitious is the right word, but yeah, let's give it a shot.
So the first topic is fat flux. I think a lot of questions come in about this, and there's a few variations on a theme. So I'll just summarize a few of these questions for you.
The first question is, why doesn't oxidation of fat necessarily mean you're losing total body fat? If I eat a low carb diet and become a, quote, fat-burning machine, end quote, why don't I always lose fat on this diet? Another way of saying this too is, the question is, if I'm in ketosis, doesn't it mean I'm burning fat? And just for the record, this question came in from ketogenic man, inside joke.

**Peter Attia** (3:19)
We get this question in one form or another constantly. So I think that's why we decided to just dedicate an entire segment to this, because it's super important and it is confusing, right? So just to be clear, let's just get the punchline out of the way first. You can absolutely be in ketosis and gain weight. You can absolutely be, quote unquote, fat burning machine and still accumulate fat.
Let's go one step further and accept the fact that we're going to use a bit of shorthand here, which is gaining weight and gaining fat. We're going to talk about interchangeably. Is that fair? Because, I mean, when people say I want to lose weight, what they really mean is I want to lose fat. And when people say I want to gain weight, they usually mean I want to gain muscle. So if we can simplify this a little bit and say that people rarely want to lose muscle and gain fat, I think it helps to think about this kind of like an engineering problem, which is always dangerous in biology because engineering is frankly cleaner and neater than biology. But I do think that we can simplify this problem without rendering our simplification unhelpful. And in doing so, really start to understand the ins and outs of this. So if we take the example you gave, Bob, which is a person who says, hey, I want to lose excess body fat. And the approach I'm taking is a ketogenic diet or some form of low carbohydrate diet. Does it guarantee that I'm going to lose weight? Well, again, let's break it down. We already said the first thing is losing weight means losing fat. And now let's break that down one step further. How do you lose fat?