The only diet that has ever worked for me was the one I did a couple of years ago (before getting pregnant with my son). I dropped carbs from one meal, and one meal only. Breakfast. I went from eating a bowl of cereal every day to eating a bowl of plain low-fat yogurt mixed with 1/2 a small can of fruit in light syrup every day.
And I walked two miles every morning.
Lost 30 pounds in two months, so I know it works and I can do it. Unfortunatley, my work schedule has changed, and I have a new baby, so walking in the morning isn’t really possible right now. But I know I can do it, and when my situation changes, I’ll get back on it.
However, I know that for me, neither diet on its own nor exercise on its own will do anything. It’s gotta be both. On the upside, quitting breakfast cereal was virtually the only dietary change I made. (Apart from just not going back for seconds at dinner, and just generally taking smaller portions. One big spoonful of dinner, instead of two.) So it was quite painless. Good luck. 😀