From Monday to Friday, you're a model dieter. But what happens on weekends when you go out to dinner?

Most dieters agree it's a lot harder to stick to a low-calorie diet when eating out.

It may be more difficult, but it's not impossible.

Here are some tips to help: BREAKFAST

Ask for skim milk with cereal instead of whole.

Order poached or boiled eggs -- they're made without fat -- instead of fried.

Order toast without butter, or with butter on the side. Wait till toast cools before buttering -- it will absorb less.

If you order an omlette, have it plain or with herbs or mushrooms instead of with cheese or ham.

Ask for plain milk with coffee instead of cream or half and half. LUNCH AND DINNER

Don't let the waiter put the bread basket on the table.

Start meals with low calorie appetizers like melon, tomato juice, raw clams, oysters or clear soups.

Salads or raw cut up vegetables are great, but make sure they're not doused with dressing. Use lemon, vinegar and freshly ground pepper instead. If you just use dressing, order it on the side.

Order meats broiled instead of sauteed or fried.

Trim all visible fat from meat.

Eat only half the meat on your plate.

Order fish instead of meat.

Remove the skin from chicken and duck.

Don't be fooled by "diet plates." A hamburger and a scoop of cottage cheese is higher in claories than a hamburger on a bun.

Order vegetarian main dishes whenever possible, they're often lower in calories.

Order half portions of pasta.

Don't butter baked potatoes.

Order steamed vegetables if possible.

Ask that all foods be brought to you without sauces and gravies.

Instead of a vegetable and potato to accompany your main course, ask for a salad and a vegetable or a double salad.

Drink mineral water instead of alcoholic beverages.

Order espresso with a twist of lemon instead of coffee with milk or cream after dinner.

Have sherbet or fruit salad for dessert instead of calorific cakes, puddings and pies.

Ask the waiter how dishes are prepared so that you're not surprised when you find your meat and vegetables swimming in gravy.

Beware of:

Dishes prepared "en croute" -- in a pastry crust.

Foods served "a l huile" -- with oil, "a la russe" -- in a mayonnaise dressing, "a la bechamel" -- in a buttery white sauce, with "Hollandaise sauce" -- a thick creamy sauce made with egg yolks, butter and lemon.