Modify the meals
Most every restaurant I have been to will modify the meals they serve.
Eat salads with light dressing on the side, avoid saturated fats such as in meat and dairy. Eat plenty of fruits and vegetables, raw is best or lightly steamed. Very lean meats such as chicken, turkey, or fish grilled. Say you wanted a pizza one night, get an all veg, very light cheese, extra pizza sauce, thin crust with salad.