It has been scientifically proven that consuming fewer calories than you expend over the long term will greatly reduce body fat.
One reason the COVID-19 death rate has been low in Japan despite having a high infection rate and a high proportion of elderly population is that they have very little obesity. I don't support the coercive legal measures they use under the 2008 ”Metabo Law". But strictly from a public health standpoint they have proven effective.
https://www.pri.org/stories/2009-11-10/fat-japan-youre-break...