Eat
Not too much
Mostly vegetables
and move around more than you normally do.

Different answers for different people. To modify your question you would have to include 'what actually works'. If eating less and exercising are not possible through discipline then maybe bariatric Sleeve surgery is an answer for an obese person. I had it done 3 weeks ago and its like magic. Although pigging out is a thing of the past for me.

God bless you.