Does kimchi reduce beer bellies?

Executive summary

I summarised the issues with this paper in a BMJ rapid response, which was published on March 11th here (Ref 1).

* A study was undertaken in Korea, which led to headline claims that eating kimchi three times a day can reduce the size of your beer belly.

* The study was a population study (with the usual limitations of these, therefore). It involved 115,726 people, aged 40-69, mostly female. It aimed to review obesity, as defined by BMI and waist circumference, with kimchi intake.

* It used Korean, not western, definitions of obesity. The Korean definition of obesity is the western definition of overweight. There should have been no headlines about obesity in western media, as obesity in our world had not been studied.

* Men and women were studied separately. They were divided into five groups for most of the analysis. At baseline, higher kimchi intake was associated with higher BMI and higher abdominal obesity. That was the opposite of the headlines. Adjustment changed everything.

* The claimed results had no consistency or rationale (see the BMJ rapid response). Why were there findings for men and not women? Why findings for some serving sizes and not others? Why for some kimchi and not other types? Why did anything make any difference?

* The only bit that made sense was "This research was supported by grants from the World Institute of Kimchi” and “Two authors are members of the staff at the World Institute of Kimchi.”