In new research presented at the North American Association for the Study of Obesity conference in October in Ft. Lauderdale, scientists at Penn State University found that volunteers who ate a big salad before eating a main course of cheese tortellini ate 107 fewer calories overall than volunteers who didn’t have a first-course salad.

“This is great stuff,” smiles Jeff Novick, Director of Nutrition at the Pritikin Longevity Center® & Spa. “In our Calorie Density lecture at the Center, we teach six guidelines for incorporating the principles of calorie density in daily life. Guideline #3 is: Begin each meal with the foods that are lowest in calorie density – fresh vegetables. For cutting down on your total calorie intake, it really works, as the Penn State researchers found.”

One important caveat: Stick to low-calorie dressings and skip high-fat, high-calorie ingredients like cheese, bacon, and croutons. When the volunteers ate salads full of calorie-dense dressings and condiments, they ended up eating the most calories – even more than volunteers who were told to skip salads and go straight for the tortellini.

The good news: The subjects rated the salads equally satisfying, and didn’t notice the difference between the full-fat dressings and the lower-fat ones, most likely because the taste of low-fat varieties has greatly improved lately, says lead researcher Barbara Rolls.

The seven-week study looked at six salads that differed in fat, size, and calories. For the 42 volunteers involved, the salads that were the most effective at reducing overall calorie consumption had the following characteristics:

1. Low in fat (just 14% of calories from fat).

2. Big in size.

Three cups of low-fat salad were much better at curtailing tortellini consumption than 1 1/2 cups.

3. Low in calories.

The salads low in calories and high in fresh, low-calorie veggies like romaine lettuce, carrots, tomatoes, cucumbers and celery did the best job at cutting overall calories for the meal. These salads (all three cups worth) added up to a mere 100 calories. (The salads with cheese, full-fat dressings, and bacon bits quadrupled the calorie count – to 400 calories.)