Diet and exercise equal in shedding pounds?

For those of you who follow both the "diet and exercise" way of losing weight and staying trim, do you know which method actually works better?

There are some people I know that swear by daily exercise as the reason they stay lean and trim -- and yet others say that portion control and calorie counting are the answer (even without exercise).

Which is correct? U.S. researchers now say that both dieting and exercise are equally effective at losing and keeping off the pounds. Do you agree?