Childhood Obesity Chapter 7

Getting to the Heart of Things


The Miracle of the Cardiovascular System

The cardiovascular system consists of the heart, the blood vessels, and the blood itself. Blood is mostly made up of plasma and red and white blood cells. But it contains many other substances as well, like platelets, hormones, and nutrients such as glucose. The cardiovascular system distributes these substances throughout the body as needed and collects waste products from your cells for elimination. READ MORE

Your child's heart started beating 6 weeks after conception, and it will continue to beat about 100,000 times day, resting only between beats, until the end of his or her life. Its only function is to circulate the blood that nourishes and sustains every cell.

It pumps the 6 quarts of blood your child's body contains through his or her entire circulatory system—over 60,000 miles of arteries, veins, and capillaries, more than twice the distance around the equator of the Earth—and it does that three times a minute. LESS


Obesity and Cardiovascular Complications

Obesity and its related conditions, such as high blood pressure, abnormal glucose tolerance, and high lipid levels, are major risk factors for cardiovascular disease (CVD), diseases of the heart and blood vessels. Most of us think of CVD, the leading cause of death in the US, as an adult disease. But CVD can begin early on, even in childhood, and get progressively worse. Obese children and children with abnormally high blood cholesterol and triglyceride levels can develop fatty streaks in their arteries, the first steps in the formation of plaques. Some may even develop plaques. CVD has become a pediatric disease. READ MORE

When obesity starts in childhood, its associated diseases and complications, especially cardiovascular disease, are likely to strike at younger and younger ages. This means that average life spans for children in the US today may be 2-5 years less than they were for their parents, making this the first generation in the country's history that will live shorter and less healthy lives than their parents.

If your child has risk factors for CVD, it's urgent that steps be taken both to monitor and to improve his or her cardiovascular health. Prevention of CVD is a lifelong concern—and a matter of life or death. LESS


Atherosclerosis and Plaque

There's a saying, “You're as old as your arteries.” By that measure, some early teens are already middle-aged! Researchers examined the arterial plaque buildup in teenagers (average age: 13) who were obese or who had high cholesterol or triglyceride levels and found the buildup was similar to levels found in 45-year-old adults. READ MORE

Plaque begins with chronic (long-term) inflammation of the lining of the arteries. This inflammation can be caused by many things: eating too many refined carbohydrates, smoking, and drinking too much alcohol are among them. Overweight and obesity, too, can cause chronic inflammation of the arterial lining, because fat cells produce many inflammatory substances that enter the bloodstream. Parts of the immune system, like white blood cells, start to accumulate at areas of the blood vessel damaged by inflammation. Together with cholesterol, calcium, and other materials, they form the hard, fibrous lesions called plaques. The blood vessels thicken and stiffen, a condition called atherosclerosis.

Plaques may build up to the point that they impede blood flow through a vessel. If they impede circulation to the heart muscle, the result can be angina. Or, a plaque may rupture. A clot may form at the site of the rupture in an attempt to “heal” it. Then the clot may block blood flow completely. If it break offs and travels to other parts of the body and becomes stuck—for instance, in the carotid arteries of the neck or in the blood vessels of the brain—a clot can cause a stroke. If it cuts off flow to the heart's coronary arteries, the result can be a heart attack. LESS


High Cholesterol

If a child or adolescent has a family history of high cholesterol or of heart disease, the American Academy of Pediatrics (AAP) recommends screening (testing) for cholesterol. Screening is also recommended if the family history is unknown but the child has risk factors for heart disease, such as obesity, high blood pressure, or diabetes. Screening should take place after age 2, but no later than age 10. READ MORE

The table below shows the AAP recommended guidelines for cholesterol levels for children and adolescents:

Category Percentile Total Cholesterol (mg/dL) LDL (mg/dL)
Acceptable <75th <170 <110
Borderline 75th–95th 170–199 110–129
Elevated >95th >200 >130




Hypertension (high blood pressure) occurs when the pressure of the blood against the arterial wall is too high. It's sometimes called “the silent killer” because, although it frequently has no symptoms, it can be deadly. High blood pressure can cause heart disease, atherosclerosis, kidney disease, and other types of damage. READ MORE

Obese children have about three times the risk for hypertension as nonobese children. This may be due to a number of factors, including insulin resistance, overactivity of the sympathetic nervous system, thickened blood vessels, and the simple fact that 1 lb of fat requires 1 mile of capillaries to feed it. The more blood vessels, the more pressure needed to move the blood.

High blood pressure in children and adolescents isn't determined by a simple target blood pressure reading as it is in adults. What's considered to be normal blood pressure changes as the child grows. So hypertension in children is defined as blood pressure that is the same as, or higher than, blood pressure in 95% of children of the same age, sex, and height. Your healthcare provider can tell you if your child's blood pressure is considered to be high. LESS


Type 2 Diabetes

Type 2 diabetes generally develops in obese children who are 10-19 years old and have a strong family history of type 2 diabetes along with insulin resistance. Type 2 diabetes is a serious, long-term condition. It can cause damage to organs and tissues throughout the body, including cardiovascular disease, vision damage, kidney disease, and nerve damage. READ MORE

Normally, insulin produced by your pancreas acts as a sort of chemical key to get certain cells, including muscle and fat cells, to permit glucose (blood sugar) to enter them. The glucose is then either used immediately for energy or stored for future energy needs. In type 2 diabetes, these cells stop admitting glucose, even when insulin is present. Glucose then builds up in the bloodstream.

Diabetes Damage
High levels of blood sugar act like a toxin to many tissues of the body, including the lining of the blood vessels. Large vessels, like arteries, can become stiff and thickened. Tiny capillary vessels become fragile and start to leak. Damage to the vessels can cause vision problems and even blindness, kidney disease, heart disease and stroke, and other problems. Nerve damage, causing numbness, can result from lack of blood supply to the nerves and damage to their covering.

Experts think that the current epidemic of childhood obesity is going to result in an epidemic of type 2 diabetes. One of the most alarming things about type 2 diabetes is that the longer a person has diabetes, the more likely he or she is to develop devastating complications. This means that kids who develop diabetes are more likely to have a greater number of very serious complications and to have shorter lives.

What's more, researchers have found that obese adolescents with type 2 diabetes perform worse on tests that measure intellectual functioning, memory, and spelling. They also found abnormalities in the white matter of their brains. The researchers aren't sure how type 2 diabetes damages the brain. It may be because the brain uses glucose as fuel, and diabetes interferes with the body's ability to regulate the amount of blood sugar that gets into brain cells. LESS


Testing for Diabetes

Type 2 diabetes is especially dangerous in children because it can go undiagnosed for years, especially as kids may have few or no symptoms. Blood tests are needed for diagnosis.

The American Diabetes Association recommends that youths who are overweight or obese (defined as BMI >85th percentile for age and sex, weight for height >85th percentile, or weight >120% of ideal [50th percentile] for height) with any two of the risk factors listed below be screened. READ MORE

Risk factors:

  • Family history of diabetes (ie, parents or siblings with diabetes)

  • Inactive lifestyle

  • Race/ethnicity (eg, African Americans, Hispanic Americans, Native Americans, Asian-Americans, and Pacific Islanders)

  • Previously identified IFG or IGT

  • History of GDM or delivery of a baby weighing >9 lbs

  • High blood pressure

  • Polycystic ovary syndrome

  • Family history of type 2 diabetes in parents or siblings

  • Being a Native American, African American, Hispanic American, or Asian/South Pacific Islander

  • Insulin resistance or conditions associated with insulin resistance: high blood pressure, abnormal cholesterol or triglyceride levels, acanthosis nigricans (dark, thick, velvety skin in body folds and creases), or polycystic ovary syndrome

  • Having had gestational diabetes or delivery of a baby weighing >9 lbs



Metabolic Syndrome

Metabolic syndrome isn't just one condition, but rather a cluster of conditions including:

  • Obesity

  • Abnormal blood lipids (cholesterol, triglycerides)

  • Hypertension

  • Abnormal glucose metabolism

Having metabolic syndrome means a having a high likelihood of getting cardiovascular disease. There's strong evidence that metabolic syndrome begins in childhood—which means that cardiovascular risk can begin in childhood as well. No fewer than 30% of moderately obese and 50% of severely obese children and adolescents have metabolic syndrome. READ MORE

As yet, there isn't a universally accepted definition of metabolic syndrome in children. One definition specifies that the child must have:

  • Waist circumference greater than 90th percentile for the age, gender, and ethnicity

  • Fasting glucose of greater than 110 mg/dL

  • Blood pressure greater than 90th percentile for age and height

  • Fasting triglycerides greater than 110 mg/dL

  • HDL-cholesterol less than 40 mg/dL

Other researchers have used slightly different definitions of metabolic syndrome in children. LESS


Enlarged Heart

Being obese increases the demands made upon a child's heart. Fat tissue isn't dormant. It's metabolically active, and it requires a supply of blood to support its operations. A child with 100 lbs (45 kg) of fat requires an increased blood flow of up to 3 pints (1.5 L) per minute. Obesity also increases total body oxygen consumption. Your resting heart rate doesn't change if you're obese, so stroke volume—the amount of blood pumped out of the heart with every beat—has to increase to keep up with the body's demand for oxygen. The child's heart has to work harder to pump sufficient blood out. This can cause the heart to enlarge and, at the same time, pump less effectively. An enlarged heart can eventually result in congestive heart failure. The symptoms are shortness of breath, dizziness, irregular heartbeat, heart palpitations, and fluid retention.

Photo credit of boy with drink
Copyright 2009 Ed Yourdon
