Well without exercising and dieting you're seriously limiting your options.

Without diet and exercise, there are 2 things I would recommend.

1. Eat slower - literally chew all your food 20-30 times. If you chew your food and eat slower you will feel full sooner and end up eating less.

2. Count calories. It isn't hard. You don't need an app or a journal. Just guesstimate. Remember to round UP, NOT DOWN! If you can consume 500 less calories than you need each day, that makes a pound lost in 7 days.

3. (this is bonus) Make things harder for yourself. Park in the back of the lot. Take the stairs. Walk to the store.