Want To Be Healthy? It Pays to Do The Math

by Jo-Ann Heslin, MA, RD, CDN on February 10, 2009 · 1 comment

Remember complaining you’d never use the skills you learned in math class? When would you ever need to multiply, divide or figure out percentages?

Now—if you want to take charge of your weight and health. Math can help you use nutrition labels to your advantage, making the best choices about what to buy and how much to eat. Math can help you understand your risk for disease. Math can help you lose weight, control diabetes, or lower your cholesterol.

Luckily, understanding math as it relates to health really isn’t that hard. Let’s go through a few simple examples and you’ll be a nutrition math whiz before we’re through.

Figuring Out Risk
Question: What is the highest risk – 1 in 1000, 1 in 100, or 1 in 10?

Answer: 1 in 10, which equals a 10% chance. Did you get that one right? If not, let’s make probability equations or percentages into a simple picture in your mind. If you made the question above into groups of people, you would quickly see the answer. One in 10 is a bigger piece of the whole group than 1 in 100, or 1 in 1000. Turn every percentage into a group of people. If 54% of women are at risk for heart disease that means 54 out of every 100 women are at risk.

Let’s try that again. Did you know that 47% of Americans have trouble doing math? Right – 47 out every 100 people stumble over math problems. That’s a pretty big bunch, so you are not alone.

Counting Calories
Question: The nutrition label on a 20 ounce energy drink says there are 110 calories in a serving. That’s simple if a serving is 20 ounces. But, the label says the bottle equal 2.5 servings. If you drink the whole bottle—which most of us do—how many calories did you consume?

Answer: 275 calories. Less than one-third of people asked got this answer right. It’s not easy because it takes a few steps. But, once you understand the steps you can apply them to any food you eat.

If a 20 ounce bottle has 2.5 servings and one serving equals 110 calories you can approach the math in two ways. You can multiply 110 calories by 2.5 servings to equal 275 calories. You multiplied the amount of calories in 1 serving times the total number of servings in the bottle. Or, a more visual approach to the same problem is to think about the energy drink as 2 1⁄2 glasses. Add 110 (8 ounces) + 110 (8 ounces) + 55 (4 ounces) to equal 275 calories in 20 ounces.

Calculating Carbs
Question: A bagel has 60 grams of carbohydrate. An average slice of bread contains 15 grams of carb. You have diabetes and need to count carbs. How much of the bagel can you eat to equal 2 slices of bread?

Answer: Half of the bagel. 15 (the amount of carbs in a slice of bread) times 2 is 30. 30 is half of 60 (the amount of carbs in the bagel). You may be surprised by that; most people are. But if you are watching carbs to control your blood sugar it is an important to be able to estimate the carbs found in foods.

Solving for Sodium
Question: You have high blood pressure and need to limit sodium to less than 2,000 milligrams a day. A can of soup has 650 milligrams of sodium in a serving. The catch—one serving equals 1 cup and you usually eat the whole can, which has 2 cups. How much sodium is in the can of soup? And how much sodium do you have left to eat for the rest of the day?

Answer: The can of soup equals 2 servings. Each serving has 650 milligrams of sodium, so, 650 + 650 = 1300 milligrams of sodium in the entire can of soup. To figure out how much sodium is left for the rest of the day, 1300 subtracted from 2000 equals 700 milligrams of sodium remaining.

By making the decision to have the can of soup you have used up almost two-thirds of your sodium for the day. Knowing this might guide you to select a different option for lunch. Or, if you eat the soup, you know you need to select lower sodium foods at dinner.

Calculating Cholesterol
Question: You are watching your cholesterol and the doctor told you to eat 300 milligrams or less cholesterol per day. You’ve planned to splurge on a steak for dinner. You ate cereal for breakfast and a salad for lunch, both very low cholesterol choices. You have 250 milligrams of cholesterol left for your steak. If steak averages 75 milligrams in three ounces, how large a steak can you eat for dinner? The math is a little more complicated, but you can do it.

Answer: Slightly less than 10 ounces. You need to divide the 75 milligrams of cholesterol in the steak into the 250 milligrams of cholesterol left for the day. The answer is 3.3. This equals 3.3 times a 3-ounce serving, or slightly less than 10 ounces. Remember, there were 75 milligrams of cholesterol in 3 ounces of steak. Do you feel like you are calculating dinner or sitting for a college entrance exam? Most of us can’t do this math in our heads. Feel free to grab a calculator.

A good deal of health information involves numbers. Practice your new found math skills. You’ll be amazed at the information you’ll discover. Using food sizes, calories and label information is a great way to make math come alive for kids and grandkids, too. And, you’ll be giving them skills that will guarantee not only good grades but good health as well.

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