2809: [Part 2] Reflections on the US News & World Report Diet Rankings by Stephen Guyenet on Nutrition Advice

[00:00:00] This is Optimal Health Daily. Reflections on the US News and World Report Diet Rankings and my involvement in them. Part 2 by Stephen Guyenet of stephanguyenet.com and I'm Dr. Neal.

[00:00:12] Hello, happy Tuesday. Welcome back to Optimal Health Daily where I simply read to you from the best health and fitness blogs for free. I cover fitness, nutrition, stress management, weight management, and lots more. This is just like an audio book but like from a bunch of different authors.

[00:00:27] And we always get permission from the sites in case you're wondering. Now today's post is part two from yesterday. So if you're new here or skipping around, I'd recommend listening to yesterday's episode first.

[00:00:39] Now what's great about today's author is that he's a doctor, he has a PhD, he cites research which you know I love, and so he always backs up his opinions with the data that's out there.

[00:00:51] And again, long time listeners of this show, you know I'm a big fan of that. And today we're going to talk about his opinion on the ketogenic diet.

[00:00:59] So I'm sure you're excited to hear that. Let's hear part two and continue optimizing your life.

[00:01:08] Reflections on the US News and World Report Diet Rankings and my involvement in them. Part 2 by Stephen Guyenet of stephanguyenet.com.

[00:01:17] The ketogenic diet. The ketogenic diet is a very low carbohydrate, high fat, moderate protein eating style that forces the body to run almost entirely on fat for fuel.

[00:01:30] It's extremely popular right now. Although the popularity of individual diets waxes and wanes, I tend to think that there is usually a nugget of truth underneath the hype.

[00:01:40] The ketogenic diet limped into last place in the rankings, tied with the Dukan diet, which is a high protein, low carb, low fat, rapid weight loss diet.

[00:01:50] It was rated by the panel as fairly effective for short term weight loss, not very effective for long term weight loss, very unhealthy, and very difficult to follow.

[00:01:59] Unsurprisingly, given its popularity, the snub was not well received by ketogenic diet fans.

[00:02:04] I don't remember exactly how I rated it myself, but here's the gist of it.

[00:02:08] I think very low carbohydrate diets, like the ketogenic diet, are some of the more effective diets for short term weight loss.

[00:02:15] Although no diet is a silver bullet.

[00:02:17] Ketogenic diets can also cause weight loss in animal models under tightly controlled conditions.

[00:02:22] I don't know how effective it is for long term weight loss, and the evidence in humans doesn't seem very informative to me.

[00:02:28] But I seriously doubt it's less effective than diets like the Mediterranean and vegetarian diets that aren't even weight loss diets.

[00:02:35] In general, my observation is that the more extreme you are on the carbohydrate to fat continuum, the more a diet tends to promote appetite control and weight loss.

[00:02:44] Very low carbohydrate and very low fat diets both tend to be more effective for weight loss than their more moderate counterparts.

[00:02:51] And I suspect this also applies in the long run, at least to some extent.

[00:02:55] This is supported by animal research, which mostly seems to suggest that ketogenic diets can curtail long term body fat gain.

[00:03:03] I probably gave it a 2 or a 3 out of 5 in health, assuming that someone is coming from a typical unhealthy diet.

[00:03:10] The primary reason for this mediocre score is simply that its long term effects on human health aren't well known.

[00:03:16] I can't really say that ketogenic diets aren't healthy in the long run, but I also can't say that they are healthy.

[00:03:20] And that uncertainty makes me feel wary.

[00:03:23] This concern is compounded by the fact that, to my knowledge, no traditionally living human population has ever been shown to exist in a state of chronic ketosis, which is what the diet promotes.

[00:03:35] Even the Arctic Inuit, who traditionally eat a high fat, low carbohydrate diet, were not in chronic ketosis.

[00:03:42] And the reason is rather troubling for ketogenic dieters.

[00:03:45] A genetic mutation preventing ketone production spread rapidly throughout the ancestral Inuit population, suggesting that avoiding ketone production conferred a powerful survival advantage.

[00:03:58] Furthermore, few of the people listening to this are likely descended from Inuit, and their genomes weren't shaped by thousands of years of eating the Inuit diet.

[00:04:07] The vast majority of traditional diets that have been documented contain enough carbohydrate and or protein to prevent ketosis, although the amount of carbohydrate varies greatly.

[00:04:17] Long-term nutritional ketosis doesn't appear to be part of the ancestral human metabolic spectrum.

[00:04:23] Contrary to popular belief, it is probably not paleo or ancestral.

[00:04:27] Shouldn't that worry us a little?

[00:04:29] The animal research on the health impacts of the ketogenic diet is a mixed bag.

[00:04:33] The diet usually prevents weight gain, and its effects on lifespan are either neutral or beneficial in mice, which is reassuring.

[00:04:40] However, it tends to cause fat accumulation and inflammation or injury in the liver and other tissues.

[00:04:46] Its effects on insulin sensitivity in animal models are inconsistent between studies.

[00:04:52] Rodents don't naturally develop human-like cardiovascular disease, so they can't help us understand the diet's long-term impacts on the heart and blood vessels.

[00:05:00] That said, we do have multiple randomized trials of very low-carbohydrate diets, and they have generally found little evidence of harm and some evidence of benefit in people who have obesity and or diabetes in the short to medium term.

[00:05:15] About the worst we can say is that they don't lower bad or LDL cholesterol as much as other diets.

[00:05:21] These findings make it seem less likely that long-term effects are catastrophic.

[00:05:24] It's also hard to deny that some people appear to benefit from the diet, particularly people with blood glucose control problems such as diabetes.

[00:05:33] If the alternative is having poorly controlled blood glucose or using blood glucose-suppressing drugs and injecting insulin,

[00:05:40] I can see how a very low-carbohydrate diet would start to make sense.

[00:05:44] We still need studies, though, on whether the diet can prevent the complications of diabetes such as heart attacks.

[00:05:50] For people who are overweight, have blood glucose control issues, and who react well to it,

[00:05:56] very low-carbohydrate diets seem like a viable option, and they don't appear to cause obvious harm.

[00:06:01] We still have uncertainty about the long-term effects of such a diet, but given the alternatives, I don't think it's unreasonable to try it.

[00:06:08] Let's be honest, though.

[00:06:10] Most people can't stick with it.

[00:06:12] I agree with the other reviewers on this.

[00:06:14] The more extreme a diet, the harder it is to adhere to, and the ketogenic diet is extreme.

[00:06:20] But wait, you say.

[00:06:21] I've been on the ketogenic diet for five years, and it's easy.

[00:06:24] That may be true, but randomized controlled trials don't lie.

[00:06:28] The average person can't even stick with the diet for six months, as judged by urinary ketone levels.

[00:06:34] The minority of people who find it easy and get good results and stick with it are the ones who write about it on the internet.

[00:06:40] For the record, I'm not against the ketogenic diet, and I doubt it's a health disaster for people who tolerate it well.

[00:06:47] I do think people who adopt it should be aware of the uncertainty about its long-term effects.

[00:06:52] As with any extreme diet, it has strengths and weaknesses, and is probably best viewed as a medical intervention,

[00:06:58] like drugs or surgery, rather than a tool for supporting general health.

[00:07:02] I think it's interesting enough that it deserves further research, particularly in the setting of diabetes.

[00:07:11] You just listened to part two of the post titled,

[00:07:14] Reflections on the U.S. News and World Report Diet Rankings, and My Involvement in Them,

[00:07:19] by Stephan Guillenet of StephanGuyenet.com.

[00:07:22] And I'll be right back with my commentary.

[00:07:24] Dr. Neil here for my commentary.

[00:07:27] I love, love, love Dr. Guillenet's analysis.

[00:07:30] The ketogenic diet was supposedly first discovered in the late 18 or early 1900s.

[00:07:36] Some researchers noticed that the Inuit population never suffered from the same chronic diseases that the rest of us did.

[00:07:43] And what they observed was that their diet was made mostly of fat.

[00:07:47] Think lots of whale blubber.

[00:07:49] And because they typically spend most of their lives in snowy Arctic regions,

[00:07:54] there weren't a whole lot of vegetables or grains to consume.

[00:07:57] And so the researcher believed that it was this high-fat, low-carbohydrate, low-grain diet,

[00:08:03] and moderate protein because all the fish and whale they ate,

[00:08:06] that's what led to the lower risk for chronic disease.

[00:08:09] But here's something that nobody talks about, and I'm so glad Dr. Guillenet mentioned it.

[00:08:14] The Inuit population had a genetic mutation,

[00:08:18] which prevented them from going into long-term ketosis.

[00:08:22] Do the rest of us have that?

[00:08:24] Who knows? You'll have to get tested.

[00:08:26] But Dr. Guillenet estimates that we probably don't have that.

[00:08:29] And so because our ancestors were not likely descended from the Inuit population,

[00:08:35] our ancestors ended up eating grains in moderation,

[00:08:38] and protein in moderation, and fat in moderation.

[00:08:41] Okay, so that's a great point that he makes.

[00:08:43] That's one.

[00:08:44] Two, he says, let's be honest, people can't stick with the ketogenic diet.

[00:08:49] Essentially eating about 70% of your calories from fat every day, that's tough.

[00:08:54] And he didn't even mention what the side effects of doing that might be like.

[00:08:58] And he slyly mentioned a way to see how long people tend to stick with it.

[00:09:03] He mentioned something called urinary ketone levels.

[00:09:06] What that means is researchers will actually collect urine samples from those in a study,

[00:09:11] and then they will analyze it to see, is the person following the diet?

[00:09:16] So you can imagine those results don't lie.

[00:09:19] Think of it this way.

[00:09:20] When a person's in a study, and they're asked by the researchers,

[00:09:23] hey, have you been following the diet we've assigned to you?

[00:09:26] So even though they may have not been following the diet,

[00:09:29] they'll lie to the researcher's face, and they'll say,

[00:09:31] sure I have.

[00:09:32] It's been going great, doc.

[00:09:34] But in reality, they went home and had some pizza and some cake.

[00:09:38] So the researcher says, okay, that's what you tell me.

[00:09:41] Let's look at your urine.

[00:09:42] Let's see what's going on there, because that doesn't lie.

[00:09:45] And when they analyze the urine, they found, uh-oh,

[00:09:48] the person's been cheating on their diet.

[00:09:49] And so when researchers use that to see if people are following the diet,

[00:09:53] turns out people can't stick to the ketogenic diet for longer than six months.

[00:09:58] And like he said, those that are successful and talk about how great it is,

[00:10:02] are the minority.

[00:10:03] It's not usually what happens.

[00:10:05] Now again, I completely agree with Dr. Guine when he says,

[00:10:08] let's not completely disregard the ketogenic diet.

[00:10:12] Maybe there is something to it.

[00:10:13] But at the very minimum, let's research it some more.

[00:10:16] Let's find out what's going on and see if people can stick to it over the long term

[00:10:20] and then see what happens over the long term to their bodies.

[00:10:24] Before I go, a big thank you again for being here.

[00:10:26] Thank you for listening every day.

[00:10:27] I hope you're having a wonderful week.

[00:10:29] I'll see you back here tomorrow where your optimal life awaits.