Hi, Minzia,
I don't think so that without exercise can reduce weight. But ya, only you can maintain it by eating low fat products and healthy food as you say on holiday. And also you have to maintain a healthy diet program.
make sure the food choices you make are healthy choices. lots of fruits and vegetables, lean proteins and good carbs (whole wheat, etc). remember, as i always tell myself and anyone who asks me... it's the calories that count! what goes in must be less than what comes out. you don't want to eat more than what you're burning, so if you're trying to lose weight while not exercising, you must make sure you make up for the calorie deficit by eating less. good luck!
eat healthy,low fat products.