According to the Centers for Disease Control and Prevention, we now have twice as many kids that are overweight today as there were 20 years ago.  As I pointed out in my book, Fit Kids, several factors contribute to this dramatic increase: a lack of regular physical education in most schools, an increase in "screen time" (TV, video games, and the Internet), and an over-reliance on fast/junk food.

It seems lately that fast/junk food is garnering most of the blame.  School districts in Oakland, Sacramento, and Seattle are already removing vending machines from their schools.  Is fast/junk food a factor in the increase of our overweight children?  Absolutely!  Is it the primary cause?  I do not think so.  

FIRST LAW OF THERMODYNAMICS

Dr. Steven Blair from The Cooper Institute stated in a recent publication of Mayo Clinic Proceedings (Volume 77, Number 2), "The Fundamental cause of weight gain is energy intake that persistently exceeds energy expenditure."  In other words, we are consuming more calories (energy) than we are burning. 

The concept is very simple; just think of food as fuel.  If we eat FEWER calories than we burn, we will lose weight (a negative energy balance).  If we eat MORE calories than we burn, we will gain weight (a positive energy balance).  This is known as the first law of thermodynamics.

As Dr. Blair pointed out, since this energy balance equation has only two components, the essential question is, "What is the cause of this positive energy balance?"  Is it attributable to an increase in energy intake, a decrease in energy expenditure, or a combination of both?

HOW MUCH ARE WE EATING?

In the new book Food Politics, Dr. Marion Nestle reports that the food industry produces 3,800 calories a day for every person in the United States, up from 3,300 calories a day in the 1970s.  The inference is that Americans are eating 500 calories per day more today than in the 70s.  If that was the case, and assuming our caloric expenditure was constant, then we would all be gaining one pound per week (since one pound =3,500 calories).  While most Americans are gaining weight, it certainly does not amount to an additional pound per week.

Food production statistics and data from food disappearance balance sheets are not very reliable according to Dr. Blair.  From a scientific standpoint, the best estimate of how much our eating habits have changed is through measurement using individual dietary surveys.  Although these surveys also have limitations, Dr. Blair’s overall determination is that “the evidence suggests that energy intake in the United States has not increased during the past 40 years.”

HOW MUCH ARE WE MOVING…OR NOT MOVING?

This is a question that is rather hard to quantify.  The data suggests that participation in sports and fitness activities appears to have remained constant; however, physical activity has decreased because of increasing mechanization on the job, labor-saving devices at home, and changing personal practices.  For older adults, just think of the phenomenal growth of drive-thru restaurants, drive-thru banks, and drive-thru dry cleaners that have appeared in the last 30 years.  We simply do not move nearly as much as our parents and grandparents did.

For the younger generations sedentary time in front a screen has become a tremendous factor in the energy equation.  Today the average child spends 900 hours a year in school as compared to 1,023 hours watching TV.  One thing we do know is that if you can reduce the amount of time that a child spends in front of a television, you can reduce their Body Mass Index.  The BMI is the measurement the government uses to assess obesity.  Based on the BMI, 26 percent of the country is obese, which is approximately 30 or more pounds over ideal weight.  Even more frightening is the prediction that by 2010, 50 percent of Americans will be obese.

WHAT IS THE SOLUTION?

There is no doubt that the prevalence of obesity among children and adults is a complex issue that will need a complex solution.  We need to move more and eat less, but getting that message across will not be easy.

One area that I am very excited about is my new relationship with PepsiCo, the parent company of Pepsi, Quaker Oats, Gatorade, Tropicana, and Frito Lay.  Steve Reinemund, the CEO of PepsiCo is committed to “raising the bar” on the nutritional content of many of their products.  I have already begun meetings with key executives from PepsiCo and my staff to improve existing products and to develop new products that fit into the “good for you category.”  I feel we must have this type of corporate attitude and commitment if we truly are going to change the direction of our country’s health.

In the meantime, my personal recommendations for you have not changed:  avoid tobacco in all forms, do not abuse alcohol, manage your weight, increase your daily servings of fruits and vegetables (five is fine, but nine is divine), and don’t forget to walk the dog (even if you don’t have one!)

Sincerely,

Ken Cooper, M.D., M.P.H.

Recognized through his writings and research as the leader of the international physical fitness movement, Kenneth H. Cooper, M.D., M.P.H., has been credited with motivating more people to exercise in pursuit of good health than any other person.

From the time of his first book, Aerobics (1968), Dr. Cooper has advocated revolutionizing the field of medicine away from disease treatment to disease prevention through aerobic exercise. Dr. Cooper has educated millions of people through his 18 books, which have been translated into 41 languages and Braille. His message is direct: "It is easier to maintain good health through proper exercise, diet and emotional balance than it is to regain it once it is lost."