2808: [Part 1] Reflections on the US News & World Report Diet Rankings and my Involvement in Them by Stephan Guyenet

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[00:00:38] This is Optimal Health Daily. Reflections on the US News and World Report Diet Rankings and my Involvement in Them, Part 1 by Stephan Guyenet of StephanGuyenet.com and I'm your narrator Dr. Neal.

[00:00:51] Happy Monday and welcome to another edition of Optimal Health Daily. This is where I read some of the best blogs covering health and fitness, just like an audiobook.

[00:01:00] Now today's post talks about the rankings of popular diets, including the ketogenic diet. And it's pretty thorough, but stick with it. It has some great information.

[00:01:09] The post is a bit longer than what I typically narrate, so I'm going to break it up into two parts. Read the first half today and then finish it up for you tomorrow.

[00:01:17] I'm trying to contain my excitement, so let's jump right into today's post. Can't wait to read it for you as we optimize your life.

[00:01:28] Reflections on the US News and World Report Diet Rankings and my Involvement in Them, Part 1 by Stephan Guyenet of StephanGuyenet.com.

[00:01:37] The process. Here's how it works. US News staff summarizes information on each diet, including the diet's recommendations and what current evidence says about its effectiveness, and provides it to a panel of expert reviewers.

[00:01:51] This is the same information that is publicly available on each diet's US News webpage.

[00:01:56] It's not perfect, but they appear to put in a good faith effort, and they ask reviewers to recommend corrections if anything seems off.

[00:02:03] On the basis of this information, as well as the reviewers' existing knowledge and optional literature searches, reviewers are asked to rate the diets in a number of different ways, on a scale of 1 to 5.

[00:02:15] These scores are then compiled into four areas that are shared with the public.

[00:02:20] 1. How effective is it for short-term weight loss?

[00:02:24] 2. How effective is it for long-term weight loss?

[00:02:28] 3. How easy is it to follow?

[00:02:31] 4. How well does it support general health?

[00:02:35] Note that these quote-unquote diets also often include lifestyle modification advice, such as physical activity, and these are considered in the scoring.

[00:02:44] US News also provides an overall score for each diet, which I suspect is an average of the four scores above.

[00:02:51] General thoughts.

[00:02:52] The diet ranking system is necessarily an imperfect process.

[00:02:56] With 40 diets to review and rank, there isn't enough time to do comprehensive literature reviews to get the best possible picture of effectiveness for each diet.

[00:03:06] This less-than-comprehensive approach leaves a certain amount of room for uninformed opinions to substitute for evidence,

[00:03:13] particularly in areas of evidence that reviewers may not be very familiar with.

[00:03:17] Still, the information it provides should be more helpful for selecting diets than the current alternatives like reading Amazon reviews, googling, or asking your Aunt Martha.

[00:03:27] The review panel includes people with a diversity of backgrounds, and they don't agree on everything.

[00:03:33] This is probably by design.

[00:03:34] I often agree with the opinions of the rest of the panel, but there are also a number of places where I disagree.

[00:03:40] I'll discuss a few of those.

[00:03:42] I want to emphasize that the point of the exercise is not for everyone to agree.

[00:03:46] For the first time, the Mediterranean diet secured the top spot for best diet overall, tied with the DASH diet.

[00:03:54] I think this is appropriate.

[00:03:55] The science of nutrition and chronic disease is complex and uncertain, but in my opinion, the Mediterranean diet has more convincing evidence supporting its efficacy for general health than any other diet.

[00:04:07] It's also relatively easy to follow, which supports long-term compliance.

[00:04:12] However, it's not really a weight-loss diet, and there's very little evidence that it causes weight loss as typically applied.

[00:04:18] Hence, I'm confused about why other reviewers rated it as an effective weight-loss diet, especially in the long run.

[00:04:24] I suspect this has to do with two factors.

[00:04:27] First, a well-known randomized trial by Cheyenne colleagues found that a calorie-restricted Mediterranean diet caused weight loss that was similar to a low-carbohydrate diet and superior to a moderate, low-fat diet over a two-year period.

[00:04:42] Four years after the end of the study, so it was six years total, people who had been assigned to the Mediterranean diet were maintaining their weight loss better than people who had been assigned to the other two diets.

[00:04:54] Second, there's human nature.

[00:04:57] When we like something in general, that favorable opinion tends to color our view of more granular aspects of it, even if it isn't deserved.

[00:05:05] I think that if you adopt a standard Mediterranean eating pattern that doesn't involve calorie restriction, you may lose some weight depending on what diet you're coming from, but probably not much.

[00:05:15] I do think the diet shows promise for the long-term maintenance of lost weight, as suggested by the CHI trial.

[00:05:22] The issue came up in a few other places as well.

[00:05:25] For example, the vegetarian diet was ranked fairly well for weight loss.

[00:05:29] This view seems to be based on observational studies showing that vegetarians tend to be leaner than their meat-eating counterparts.

[00:05:35] Yet, there is little direct evidence that vegetarian diets promote meaningful weight loss, and if you expect to lose a substantial amount of weight just by cutting meat out of your diet, you're probably going to be disappointed.

[00:05:48] The ketogenic diet.

[00:05:50] Hear that on tomorrow's episode.

[00:05:56] You just listened to part one of the post titled, Reflections on the U.S. News and World Report Diet Rankings, and my involvement in them, by Stephan Guienet of StephanGuienet.com.

[00:06:07] And I'll be right back with my commentary.

[00:06:10] Dr. Neil here for my commentary.

[00:06:12] I agree with Dr. Guienet when he mentioned that the Mediterranean and DASH diets are probably some of the better diets to follow.

[00:06:19] So, as he mentioned, when we look at chronic disease risk, things like heart disease and cancer, the Mediterranean diet and the DASH diet seem to lower our risk for those.

[00:06:29] But here's the thing.

[00:06:31] The Mediterranean diet, when we as Americans think of it, we often think of pizza and pasta.

[00:06:37] And that's not truly a Mediterranean diet.

[00:06:40] That's an American version of the Mediterranean diet.

[00:06:43] So, when we're talking about the way those eat that live near the Mediterranean Sea, what we're really talking about is a diet rich with beans, vegetables, fruits, fish, whole grains, nuts and seeds, lots of olive oil.

[00:06:58] You get the idea.

[00:07:00] So, I've had patients who get very excited that I'm recommending a Mediterranean diet for them because that means they can eat lots of cheese and bread and pasta.

[00:07:09] Nope, that's not what I'm saying at all.

[00:07:13] Like Dr. Guienet's point about the vegetarian diet.

[00:07:16] Let's say you switch from your current diet, where you eat pretty much everything, to a vegetarian diet.

[00:07:22] Well, what's going to happen when you start restricting foods from your diet?

[00:07:26] You're going to remove lots of the food that you normally consume.

[00:07:29] That's going to decrease your calories, which may make you lose weight.

[00:07:33] So, when someone switches to a new diet, whether it's vegetarian or not, really, you're often just going to be cutting calories.

[00:07:40] And that's what's going to lead to weight loss.

[00:07:43] It's not the fact that it's the diet per se that's helping you.

[00:07:46] It's the fact that you started to cut out other things in your diet that then made you lose weight.

[00:07:52] Thank you for listening today and every day.

[00:07:54] Like I said, I'll be back here tomorrow to finish up this post and where we talk about the ketogenic diet.

[00:07:59] So, I'll see you there where your optimal life awaits.