December 15, 2017

Big Fat Misinformation

Q: Did you see there’s a diet that makes you burn energy ten times faster?

A: That … doesn’t sound very likely.

Q: It’s in the Herald

A: But it’s also in the Daily Mail.

Q: You could look up the research paper

A: <sigh>


A: Ok. Here it is.

Q: That took a while.

A: The story didn’t give the names of any of the researchers.

Q: Did the diet make people burn energy ten times faster?

A: No

Q: Mice?

A: It was people, but they didn’t burn energy ten times faster

Q: Are you sure?

A: Here’s the graph from the research paper: RMR stands for ‘resting metabolic rate’ and the colors indicate the groups

Q: The red line is higher.  Is that the magic diet?

A: Yes.

Q: It’s not ten times higher

A: No

Q: Ten what, then?

A: The slope of the red line is ten times as steep as the slope of the other lines

Q: They all look kinda flat to me.

A: What’s ten times not a lot?

Q: Ok. Point.  The red line looks higher right from the start. The story says “They were randomly placed into three groups”

A: … “in the order they signed up for the study.”

Q: Well, you can’t randomly assign them before they sign up. Oh.  You mean they were just allocated to each group in turn.

A: Yes.

Q: Is that international best practice?

A: No.

Q: But does the diet work?

A: I don’t think the research adds much to what’s known about this question

Q: Which is?

A: Do you really think you’re going to get a simple and definitive solution to the low-carb diet controversy from a statistical blog?

Q: Ok, can I at least have some sort of sound bite?

A: Magic diet is not magic



Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »


  • avatar
    Priscilla Allan

    I wonder how many calories are in each of the diets. Cutting carbs, and eating lots of vegetables results in a low calorie eating plan. Also, some salads can use more calories in the digestion process than they provide.

    1 month ago