Smaller portions are a big restaurant trend as customers watch their budgets and waistlines

The biggest new restaurant trend is small.

Special menus with petite, less expensive portions are popping up all over, from large chains like Olive Garden and The Cheesecake Factory to trendy urban eateries and farm-to-fork dining rooms.

Restaurants hope that offering smaller servings beyond the children’s menu will meet many different diners’ needs. Some people want to spend less when they go out. Others are looking for healthier options or trying to lose weight. Younger consumers...