Strength gains/weight gains

Jordan somewhere I read that you don’t need to gain weight to gain strength. I can’t find the article or were it was posted. Could you link it or explain to me the process behind this. I was always taught if you want strength you need to gain weight. Well now past 43 I like staying slimmer rather than “chunky”.

I haven’t published an article on it, but do discuss this in a podcast with Dr. Eric Helms, available here