I have a 1 and a 6 year old mini dachshund. I dont have a problem keeping the older dachshund's weight contro?

MY baby girl, loves to go outside and eat anything she can catch outside to gobble. I was told I needed to put her on either a high protein meal or a weight management program. Neither one of them will hardly touch the weight management food. But will fill up outside. I realize she is just a baby, but I want to keep her weight in tact. What else can I do?