You Are What You Eat

Welcome to BMI
Recent research studies have some bad news for teens who are looking forward to a summer of burgers, fries, and milkshakes. What do researchers want you to know about your weight and diet?

Just when you thought it was safe to spice your days at the beach or lazy summer afternoons at home with outdoor barbecues, fast food, and trips to the ice cream store, a report by the Centers for Disease Control (CDC) is warning teens to watch their weight. Earlier this year, a different study found that adolescents who eat too much junk food stand a greater chance of developing heart disease later in life.

Last week, the CDC—a federal research and health information agency in Atlanta, Georgia—released a set of charts to help parents and doctors identify healthy weight ranges for children. The charts are based on the increasingly popular Body Mass Index (BMI), which calculates weight and height together.

  • The CDC estimates that of young people in the United States between 6 and 17 years of age, about 5.3 million are overweight. If there are a total of 42.5 million children in this age group, what percentage are overweight?

The new BMI charts also take age into account, since children's body fat changes as they grow. The charts below show body mass for both girls and boys according to their ages.

Heart Diesease Chart

 

Source: Centers for Disease Control and Prevention

You can locate your age along the bottom line of the appropriate chart. Move your eye or finger straight up from that number until you reach the level of your BMI, as indicated on the left side of the chart. The curving lines just above and below this point indicate your BMI percentile.

So if you are a 13 year-old boy with a BMI of 21, you are almost exactly between the 75th and 85th percentiles (at about the 80th percentile). That means that your BMI is higher than 80% of the other boys in your age group.

Setting the Table
Find out the weight, height, and age of four other people under 20 years old. Then, using the charts above, complete the table below. You can find Body Mass Index (BMI) by using the following formula:

BMI = Weight/Height2


Name

Weight

Height

BMI

Percentile

Yourself

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  • How many of these BMIs are above the 50th percentile?


  • How many are above the 85th?

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Sobering Statistics
Recent studies have provided a feast of data, although you might not like the flavor. The study earlier this year on teens and junk food—from the Pacific Health Education Center in Bakersfield, California—highlighted the following problems:

  • Almost 33% of those adolescents were likely to develop high blood pressure and clogged arteries.


  • 80% were consuming more than the recommended amount of fat.


  • 49% were taking in more than the recommended amount of cholesterol.


Lack of physical exercise is compounding these problems. A survey conducted by the CDC reveals that almost 50% of young people between 12 and 21 "are not vigorously active on a regular basis," and that the percentages drop sharply between 9th and 12th grades. The reduction in physical education classes has been partly to blame, the CDC report concluded. This trend has prompted the CDC to create its Kids Walk-to-School program, which locates safe routes and encourages children to take to their feet.

While most nutritional experts recommend at least five helpings a day of fruits or vegetables, they do not all require that you give up your favorite fast foods. The Physicians Plus Nutrition Center at the University of Wisconsin offers this advice on its Web site:

Government guidelines recommend that less than 30% of your daily calories come from fat. If you want to indulge in a double cheeseburger and fries, just eat less fatty foods the rest of the day. If you eat 2,000 calories a day, you should have no more than 585 calories from fat. So if your double cheeseburger and fries contribute 387 calories of fat, you can still consume 198 more fat calories that day and still be under 30%.

The following chart provides the percentage of "calories from fat" in some popular fast foods. Calculate the total calories from fat contained in each.

Food

Total Calories

% of Calories from Fat

Calories from Fat

Whopper w/cheese

730

57%

 

Big Mac

510

46%

 

Roast Beef Sub

672

52%

 

Hard Shell Taco

220

55%

 

Source: The Physicians Plus Nutrition Center, University of Wisconsin
  • If you were to choose one of these meals, how many additional calories from fat could you eat during the same day and not exceed the 585 from the example above?

Learn More
Too much fat in the diet can affect the health of the heart and the circulatory system. Take a closer look at these areas in the Biology Gateways activity, Blood Pressure and Circulation and the Biology Explorer activity, Heart Problems.

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