I've lost more weight than David or Kim. I used no supplements unless a blood test showed a deficiency - the only thing close I still use is a fish oil capsule but that has nothing to do with my weight loss. I've been using that for years, no matter my weight.
I limit portions of foods, some severely, but I did not eliminate any totally either to lose or maintain. I was a yo-yo for years before I decided for myself what I personally needed to eat to lose weight but that I'd be okay eating the same way once the weight was gone.
My "secrets" could be wrong for someone with a different body, but they work for me.