Even more important than what you eat is how much you eat. Learn portion control. Use measuring cups and a scale. If you try to eyeball your portions, you will almost certainly overestimate. It's just human nature.

Moderate exercise will keep your body from dropping into famine mode from the reduced calories. Some exercise is pretty much mandatory for successful weight loss.

As mentioned, significant exercise will improve/add muscle, and trade weight loss for fitness increase.

I'm not going to join your commitment because after yo-yo-ing between 160 and 230 for a couple of decades, I know that even if I get it off, I won't keep it off.

Good will to you all!