Some people sweat more than others. Go for a run with a group of people on a warm day, and the differences become obvious. But what determines these variations? Answers have traditionally focused on factors like body fat percentage (more fat insulates you and makes you overheat sooner) and aerobic fitness (the fitter you are the less you sweat).
28 people is not enough to draw a conclusion from, but the article basically dismisses anything we’ve considered to be truisms to date about fat people sweating more. But it’s been a well-known fact of ecology for ages now that animals tend to be larger (and have smaller ears, tails, etc) in higher latitudes whereas the closer you get to the equator, the smaller creatures get (Bergmann’s rule). I certainly sweat a lot more when the temperature was higher.