The Keto Study That Wasn't About Keto | Dr Nicola Guess

Simon Hill (0:04)

Let me set the stage here for the listeners. So roughly one in three adults today have excess fat in their liver. And many of those adults don't know about it yet. That excess fat in the liver tends to travel with blood work that's drifting out of range. And perhaps that is something that people are more familiar with. They go and see their doctor, and their HbA1c, or their fasting glucose. And even biomarkers like ApoB or LDL cholesterol, which is a bit more commonly tested, can be somewhat out of range. And of course, when people go and see their doctor, and they get told that these things are out of range, they want to know what they can do about this, particularly with their diet, and specifically beyond just losing weight.

Because of course, we know that losing weight can help these things. Is there anything else that people can do with regards to their diet? Should they eat more or less carbs? Should they eat more or less protein, more or less fat? And then ultimately, beyond these macronutrients, just what food is more or less of? Because ultimately, that's what people are thinking about when they're at the grocery store, which is why I wanted to get you back on the show. Because there has been a new study from Sam Klein's group at Washington University that was published that I thought was really interesting. It compared three different diets looking at weight loss and some of these cardio metabolic markers and liver fat.

And I'll get you to walk us through the details of this study. But first, I'd like to get your kind of first reaction. When you saw that this study was published, I have to imagine knowing your interests and the research that you do, that you were somewhat excited to see that this study had been done.

Nicola Guess (1:59)

For sure. So one of the things you want to know as a dietitian, what helps me be a dietitian, is knowing what nutrients do in the body. What is the effect if someone changes their dietary intake on, for example, liver fat? Historically, what we've done is free living trials. So you might do low carb versus high protein, whatever it might be.

And people don't really follow those diets, first of all. You always end up with markedly different weight loss at the end. So it can't really tell you anything. There's no what we call internal validity. So lots of previous, let's broadly say, low carb trials have been interpreted as reducing carbohydrate does or doesn't affect outcome X. But that's not correct. It's more advising people to reduce carbohydrates.

Doesn't or does something, right? What I want more of is trials like this one where stuff is controlled. They controlled the weight loss beautifully and it reduces changes in weight as a confounding factor. And then you can have more confidence as saying, okay, it's the macronutrient changes here. And the other thing is that they provided all of the food in this study.

They also collected biomarkers for fidelity to the intervention. So for example, the low carb pattern, we'll get into this, but it was more of a high carb, sorry, high protein, low carb pattern. But they measured a nitrogen in the urine. That's a really good robust marker of if someone's increased their protein intake. And they also measure ketones. So it gives you some confidence that people are reducing carbs. So all of that was so exciting because it's rare, because it's expensive. But it, for the first time, I think, enabled us to say, okay, if people lose 10% weight loss, and they have markedly different diets, what is the effect of those diets on certain outcomes? It was a great, really well done state.

Simon Hill (3:55)

So just to underscore that point about the advantage of providing food. So the difference being that if you just have dieticians telling people to eat one of three diets, what happens in the real world is not always in line with what the recommendations were, because behaviour and just dietary adherence overall is not going to be the same as if you give these people the food.

Nicola Guess (4:23)

100%.

So there's a meta-analysis on trials. I think it was for weight loss, and it was like low carb, less than 50 grams a day. That's what these trials aim to test. And in this meta-analysis, they report what people actually did.

And at the end of it, some people were having 180 grams of carb a day. So you're not testing. What happens when people have less than 50 grams of carb a day? You're testing. What happens when you advise people to have less than 50 grams a day? So the beautiful thing about providing food, it's not award-based study. So we have to acknowledge that even if you provide food, in the real world, life will get in the way. Many of these participants, they'll have food delivered, and they probably on occasion went out to a restaurant and had something different. But that's why the addition of these biomarkers, looking at the amount of nitrogen in the urine and looking at ketones, it tells you broadly people were following these dietary patterns.