Andy
Retired committee member
It just seems logical, doesn’t it? Super-sizing your food can super-size you. So when I used to see claims that a bigger plate = a bigger you, it made sense.
But then a new trial rolled in, straight into my wheelhouse. It’s got everything! Old, conflicting systematic reviews! Research integrity issues! And personal interest. I’d like to lose some weight. I don’t want to have to buy all new tableware, but hey, if it’s that easy, then I guess I should think about it. I rolled up my sleeves and got stuck in.
So here are the characters in this story. First, the new trial. By Daina Kosīte and colleagues, it’s decent-sized for this kind of study – 134 adults. They were randomized to large or small plates for a self-service lunch in a purpose-built laboratory that’s meant to be home-like, but with concealed video cameras the participants are told about. They didn’t know it was how much they would eat that was being studied, though:
To conceal the true purpose of the study, at the time of recruitment, participants were informed that the study was examining the impact of time of the day on a range of mental processes, and that they had been allocated to a lunchtime session.
They had half an hour for lunch, in a “lounge room” with a TV going, and a heated food trolley.
This trial had lots of the pillars of good science: it was fully pre-registered, with a data analysis plan posted early on, too. Randomization was by an external statistician, and the data analysis was, too. The people preparing and serving meals had nothing to do with the study.
The result?
There was no clear evidence of a difference in consumption between the two groups… There was no evidence of impact on meal micro-structure, with the exception of more food being left on the plate when larger plates were used.
Does this sound familiar???
https://blogs.plos.org/absolutely-m...new-weight-loss-trial-old-systematic-reviews/Where does all this leave us? The systematic reviews end up being rather misleading, I think, in part because they have lumped too many disparate interventions together and obscured the weakness of the evidence base. The “claiming benefit” side of the ledger is compromised, too. And now we have a piece of strong evidence that doesn’t show a benefit. None of it gets directly at the question of weight loss and whether it’s worth buying a new dinner set.
Count me down as endorsing the Kosīte trial authors’ conclusion:
This study suggests that previous meta-analyses of a low-quality body of evidence may have considerably overestimated the effects of plate size on consumption. However, the possibility of a clinically significant effect – in either direction – cannot be excluded. Well-conducted trials of tableware size in real-world field settings are now needed…