Supersized portions are one reason for an increasing number of overweight Americans. Even if we don’t clean our plate, we’re still more likely to overeat, some research indicates.

What’s normal? What’s too big? The “Portion Distortion” quiz, from the National Heart, Lung and Blood Institute, shows what a typical portion looked like 20 years ago, what it looks like today and how much physical activity it will take to burn off the extra calories.

Test your knowledge of the right-size serving with these questions. For more — including fries, cookies, burgers, pizza, coffee and chicken Caesar salad — go to http://hin.nhlbi.nih.gov/portion.

1. A turkey sandwich 20 years ago had 320 calories. How many calories do you think are in today’s portion?
A. 820.
B. 510.
C. 630.

2. How long will you have to ride a bike in order to burn those extra calories?
A. 45 minutes.
B. One hour and 25 minutes.
C. Two hours and 15 minutes.

3. Chicken stir-fry was 435 calories 20 years ago (for a 2-cup portion). How many calories do you think are in today’s common portion of chicken stir-fry?
A. 625.
B. 550.
C. 865.

4. How long will you have to do aerobic dance in order to burn the extra calories?
A. Three hours
B. One hour and five minutes
C. Two hours and 10 minutes

1. A. Today’s 10-inch turkey sandwich has 820 calories. This is 500 calories more than a portion 20 years ago.

2. B. If you ride a bike for 1 hour and 25 minutes, you will burn approximately 500 calories (based on a 160-pound person).

3. C. Chicken stir-fry is often 865 calories. Many restaurant entrees are large enough for two people. Share with a friend, or eat half and take the rest home.

4. B. If you do aerobic dance for 1 hour and 5 minutes, you will burn 430 calories (based on a 130-pound person).

MORE SUGGESTIONS FOR PROPER PORTIONS

Here are other suggestions for choosing the correct portion size.

Know what you’re getting. Check a restaurant’s Web site for nutrition information, or ask before ordering. Panera Bread and Ruby Tuesday are among a handful of fast-casual restaurants that provide nutrition information for all their offerings, not just the low-fat or low-carbohydrate ones. Most fast-food chains also provide nutrition information. Order wisely by studying your choices.

Doggy-bag it. If you’re ordering at a restaurant, request that half your meal be placed in a takeout container before it’s served to you, or do it yourself at the table before starting to eat, and save it for the next day’s lunch.

Use visual cues. A serving of meat should be no bigger than a deck of cards; a portion of pasta, about the size of a tennis ball; an ounce of cheese (1 serving), about four dice.

Fill up on fruits and vegetables, especially vegetables. You’ll get beneficial nutrients, antioxidants — and a full stomach. Just make sure they’re not covered in a calorie-rich sauce or salad dressing, or prepared with pork fat or lots of sugar, such as sweet potatoes with mini marshmallows.