The Peter Attia Drive - January 20, 2020


#89 - AMA #11： All things fasting

Topics
coffee and fasting
Hosted by
Peter Attia
Mentioned
Walter Longo
Qualy #94 - Comparing the two broad types of meditation, and Peter's favorite meditation apps Qualy #99 - The steroid controversy： Mark's use of them and Peter's perspective

Episode Stats


Length

14 minutes

Words per minute

164.37

Word count

2,398

Sentence count

140


Summary

Summaries generated with gmurro/bart-large-finetuned-filtered-spotify-podcast-summ .

In this episode, Dr. Peter Atiyah is joined by Dr. Bob Kaplan to discuss what fasting is, what it is not, and why it's important to know the difference between it and alternate day fasting.

Transcript

Transcript generated with Whisper (turbo).
Topics generated with Qwen2.5-3B-Instruct.
Hosts, guests, and mentioned names generated with spaCy (en_core_web_sm), reconciled against Wikidata.
00:00:00.000 Hey everyone, welcome to a sneak peek, ask me anything or AMA episode of the drive podcast.
00:00:16.500 I'm your host, Peter Atiyah. At the end of this short episode, I'll explain how you can
00:00:20.460 access the AMA episodes in full, along with a ton of other membership benefits we've created,
00:00:25.440 or you can learn more now by going to peteratiyahmd.com forward slash subscribe.
00:00:31.140 So without further delay, here's today's sneak peek of the ask me anything episode.
00:00:39.240 Welcome to a special AMA episode focusing on my recent seven day fast, in addition to a deep dive
00:00:46.420 on fasting in general. As this is a topic we get so many questions on, we figured dedicating an entire
00:00:52.200 AMA to it would be of value. So we hope you enjoy. I'm once again joined by my head of research,
00:00:57.420 Bob Kaplan. So without further delay, here's today's special AMA focusing on fasting.
00:01:08.400 Hello and welcome to a fasting edition of ask Peter anything. Peter, how you doing?
00:01:16.080 Doing all right. And this is Bob Kaplan. So let's just jump right into the questions around fasting.
00:01:21.720 You obviously get a lot of questions on fasting. And I thought before we get into fasting,
00:01:28.580 maybe you could discuss what fasting is, a definition of fasting. So we get a lot of questions
00:01:33.220 around what is IF, what is TRF, what is ADF, what's a fasting mimicking diet, and what is prolonged
00:01:41.980 fasting, even what's an overnight fast. So I can remind you of all those. Okay. Why don't you give
00:01:48.140 them to me one at a time? Okay. So I think maybe the first one is overnight fast. When somebody
00:01:53.140 refers to an overnight fast, what is that? So that, as its name suggests, is sort of the standard fast
00:01:58.760 that almost by definition, everybody does between dinner and breakfast. So if you finished dinner at
00:02:05.060 seven o'clock in the evening rather, and you had breakfast at seven o'clock the next morning,
00:02:09.400 you would have just undergone a 12 hour overnight fast. Okay. And TRF, time restricted feeding,
00:02:16.600 some people call it TRE, time restricted eating. That is an idea where you increase that window
00:02:24.740 from just an overnight fast into a slightly longer window. So if the overnight fast that I used a moment
00:02:33.200 ago were to be put into time restricted feeding nomenclature, you would call it a 12-12, meaning 12
00:02:41.420 hours of fasting followed by a 12 hour window, say 7am to 7pm in which one would eat. You can extend
00:02:49.160 that and you could say a 14-10 window or a 16-8 window or an 18-6 window where the first number
00:02:57.080 generally refers to the period of time that has no nutrient exposure and then followed by the
00:03:03.260 window and time in which one would be able to consume food, typically ad libitum, meaning without
00:03:08.820 restriction. Okay. So rolling into the next one, alternate day fasting. So again, as the name suggests,
00:03:16.020 alternate day fasting is when every other day a person does something other than their traditional
00:03:23.460 ad libitum eating. Now, the most strict way that one could do an alternate day fast, which would be
00:03:29.720 quite difficult to do over the long haul, would be to literally consume nothing every other day.
00:03:35.480 More commonly when people do alternate day fasting, they have a hypocaloric day. So they might on
00:03:41.860 alternate days consume say 1,000 calories and on the non-fasting day they would consume whatever
00:03:49.120 they consume ad libitum and that might be say 2,500 to 3,000 calories.
00:03:54.240 So I know that you're somewhat of a stickler on the definition. So in that case, it's almost like
00:03:58.980 alternate day calorie restriction on the opposite day. Yeah. One way that I think about that,
00:04:04.580 actually a couple of ways that I think about it is if you're looking at a calendar for a strict
00:04:08.420 alternate day fast, if you're going to start it in January, January 1, let's say you're going to
00:04:13.560 eat in January 2nd, you're going to fast. You can mark off every even day of that month and you know
00:04:19.680 that you're fasting on that day. And then on the alternate days, you're eating. And I sometimes
00:04:24.780 think about it in terms of when you talked about TRF or time-restricted feeding or time-restricted
00:04:29.620 eating, you think about it in the context of a 24-hour clock. With alternate day fasting,
00:04:34.460 it's almost like a 48-hour clock on the alternate days. And I think it can vary quite a bit on your
00:04:40.120 feeding days that you might do a one meal a day, which would be almost like a 47-1.
00:04:46.780 That's right.
00:04:47.440 One hour of the day you're feeding and then the 47 hours you're not. I don't suspect that people
00:04:51.640 are eating between midnight and 11.59 on the feeding days. So there's probably a bigger window
00:04:56.520 than just 24 hours when you think of an alternate day fast.
00:04:59.680 Yep.
00:05:00.340 Next definition is intermittent fasting.
00:05:03.200 So this is a term that unfortunately has gained a lot of popularity. I guess I say unfortunately,
00:05:09.300 because I don't find it to be that helpful. I think what people generally mean when they say
00:05:15.020 intermittent fasting is time-restricted feeding. And in the end, who cares what people say? As long
00:05:19.380 as they know what they're talking about and know what they're referring to. But I personally don't
00:05:22.920 find the term intermittent fasting to be very accurate because I don't think that not eating for
00:05:29.480 16 hours really constitutes a fast per se. And that's why I do prefer the terminology time-restricted
00:05:36.300 feeding or time-restricted eating to describe the extension of the overnight fast. I think if you
00:05:44.300 were going to give a true meaning to the word intermittent fasting, you would describe that
00:05:50.260 sort of the way I'd describe periodic fasting, which is at some frequency, you actually undergo a fast.
00:05:57.980 And that might mean every month or every quarter or every six months or every year,
00:06:02.560 you undergo a fast that is intermittent. And again, that gets into probably another one of
00:06:08.980 the definitions you're going to ask about, which is what does fasting mean? Does fasting
00:06:13.680 necessitate a complete elimination of calories or could it also be done through reduced calories?
00:06:21.720 Yeah. Maybe one other bucket, a popular diet is the 5-2 fast,
00:06:25.260 which is instead of looking at a 24-hour window or a 48-hour window, you're looking at the calendar
00:06:30.820 week and you're selecting a couple of days where it's actually, I think it's calorie restricted,
00:06:34.880 like you said, with the alternate day fasting. So on the two days, so eating five days out of the
00:06:40.100 seven-day week, you're eating normally two days out of the seven-day week. I'm not sure if you can pick
00:06:44.480 them, whatever days you want to pick them. The usual version of that protocol is that they are not
00:06:48.520 successive, but otherwise it's sort of up to you. Okay. Yeah. And in that case,
00:06:53.320 it'll be typically a hypocaloric 400 to 600 calories, I think on your quote unquote fasting
00:06:58.680 days. Yep. Fasting mimicking. What is mimicking fasting?
00:07:04.380 Well, I think the term fast mimicking diet or fasting mimicking diet, FMD is actually a trademark
00:07:11.780 that belongs to a company that sells a product that is a pre-packaged five-day fast. I believe the
00:07:21.520 company is called El Nutera and it's based on the work of a guy by the name of Walter Longo. And it
00:07:29.120 has a very clear prescription around its macronutrients and its total caloric balance. So in other words,
00:07:37.660 to be very clear, the term fast mimicking diet is to that what the term Kleenex is to the actual tissue
00:07:45.960 that is branded Kleenex. So there are an infinite number of tissues that you can blow your nose into.
00:07:52.280 There's only one Kleenex. There are an infinite number of ways that one can do a reduced calorie
00:07:59.180 fast that approximates some of the metabolic benefits of fasting, but there is only one
00:08:05.100 fast mimicking diet or FMD. For what it's worth, that's approximately 900 to a thousand calories on the
00:08:12.820 first day. And I believe it's approximately 700 to 750 calories for days two through five. But I could
00:08:21.260 be off a little bit on that. Okay. And then last but not least, prolonged fasting or multiple day
00:08:28.640 fasting. So again, if we're now talking about absolute fasting as opposed to reduced calorie fasting of
00:08:35.940 which fast mimicking diets are a subset. So again, a reduced calorie fast would be typically from a
00:08:43.460 clinical perspective, using our patients as an example, we do anywhere from three to seven days,
00:08:50.080 typically at about 500 to 700 calories a day. We also have very different macros that we prescribe
00:08:57.860 than some of the commercial applications. But again, we call that a reduced calorie fast.
00:09:03.300 So then what you're talking about, of course, it's the simplest one to explain, actually. It's just
00:09:08.160 water only. And I say water also includes tea and some minerals, but it's no calories for a period of
00:09:16.340 time. And again, it's typically done for three to seven days at a time. I can't believe I'm going to
00:09:21.300 give you the what abouts. So what about coffee? Coffee and tea and water or just tea and water? Is there
00:09:26.220 a difference? There probably is, but again, it probably isn't as much of an issue as people want to make it
00:09:31.900 out to be. When we have patients who are quite caffeine dependent, we don't like to see them
00:09:39.680 eliminate caffeine during a fast because fasting can be challenging enough on its own. And I don't
00:09:46.860 really think it benefits someone to also go through caffeine withdrawal during that period of fasting.
00:09:52.580 So I'm sort of fortunate in this regard in that I drink coffee every day, but I don't seem to have
00:09:58.620 any dependency on it. So when I fast, I don't drink coffee, at least for the first five days. Sometimes
00:10:05.040 as a treat on days five, six, seven on those longer fasts, I'll drink a black coffee. Some observers have
00:10:11.200 suggested that enhances autophagy late enough in a fast. I'm not necessarily convinced that that's the
00:10:16.280 case. And truthfully, I think I do it just to sort of break up the board. A black coffee has never tasted
00:10:20.680 so good as it does on day five of a water only fast. But for most of the time, I don't consume
00:10:26.480 coffee, even black during a fast. And again, we make that decision very clinically with a patient.
00:10:32.500 There are some patients in whom a big part of the fasting protocol is gut rest. And in those patients,
00:10:38.360 we definitely want to avoid coffee, not so much for the caffeine, but more for some of the other
00:10:43.760 phytochemicals that are in it. Tea seems to be a little bit more forgiving. And obviously there's
00:10:48.620 plenty of caffeine in enough types of tea. So again, the caffeine is probably less the issue.
00:10:54.100 But I do think that for most patients, the sort of bread and butter, no pun intended,
00:10:59.060 of a fast is water. And that can be bubbly water, still water. You know, bubbly water is a nice way
00:11:03.580 to sort of mix it up. And as you know, I have a particular brand of bubbly water that I fancy the
00:11:09.400 most. So I go through those at a geometric rate during my fasting weeks. Okay. So obviously you alluded to
00:11:15.580 the next question, which is, well, at least one of the types. So what type of fasting do you personally
00:11:20.820 engage in and why? So why do you fast and what types of fasts? Of all those fasts we just talked
00:11:25.800 about, TRF, ADF, IF, FMD, and the prolonged fast, which ones are you engaging in and why?
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