Obese girls suffer from more severe hypertension than obese boys during their teenage years, researchers from the University of California at Merced reported in the American Physiological Society conference. Hypertension (high blood pressure) raises the risk of subsequent stroke and heart disease.

Dr Rudy Ortiz PhD, Associate Professor of Physiology and Nutrition, and team studied 1,700 teenage boys and girls aged between 13 and 17 years. They had had their blood pressure measured during a school district health survey. Their weight, height were taken, and therefore BMI (body mass index) was also calculated.

The research team categorized the children as:

  • Normal weight
  • Overweight
  • Obese

The teenagers’ blood pressures were categorized as:

  • Normal
  • Pre-elevated
  • Elevated (high)

People with a BMI of 30 or more are considered obese. Sometimes BMI is not 100% accurate in deciding whether somebody is overweight/obese or of normal weight. For example, a 100 meter Olympic gold medalist sprinter may have a higher BMI than a couch potato of the same age and height – but the athlete will have less fat and enjoy better health (muscle weighs more than fat). However, when measuring average body weights of populations of over 1,000 people, BMI is fairly reliable.

A blood pressure measurement takes two readings. During each heart between, blood pressure varies between the systolic (maximum) and diastolic (minimum) pressure:

  • Diastolic pressure – the force on the arteries between heartbeats. This is the lower of the two numbers.
  • Systolic blood pressure – the force that blood exerts on blood vessels walls when the heart contracts (pumps). This is the higher of the two readings. If a person has a high systolic measurement, their risk of stroke and heart disease is higher.

They found that among the teenagers, BMI was closely linked to mean SPB (systolic blood pressure) for both the girls and boys – the higher the BMI, the higher their SPB tended to be.

Dr. Ortiz said:

“We were able to categorize the students in different ways, first based on BMI within each of three blood pressure categories. Then we flipped that around and looked at each category of blood pressure for different weight categories. In each case, we are looking at SBP as the dependent variable.”

The researchers reported that obese teenage males have a 3.5 times higher risk of developing high systolic blood pressure than their peers of normal weight.

However, the risk for obese teen girls was 9 times higher, compared to their counterparts of normal weight.

Dr. Ortiz believes the association may be counteracting the protective effect offered by estrogen, a female hormone.

Dr. Ortiz said:

“Overall, there is a higher likelihood that those who present with both higher BMI and blood pressure will succumb to cardiovascular complications as adults.

But the findings suggest that obese females may have a higher risk of developing these problems than males.”

Perhaps the different levels of physical activity between obese boys and obese girls plays a part, the scientists added. Obese girls are 50% to 60% less physically active than obese boys.

The team said that their findings should be of concern for the obese teens when they get older, especially the obese girls.

Childhood obesity rates have increased rapidly during the last twenty years. According to WHO (World Health Organization), approximately 10% of children globally are obese/overweight.

In the USA obesity among children has almost tripled during the last 25 years. Today about 17% of American children and teens are obese, and 32% are overweight. Approximately one third of American babies/toddlers aged between 9 months and two years are overweight/obese.

Variation in body fat 12577
Childhood obesity is becoming a serious problem in the USA, UK, Australia and several other countries

Written by Christian Nordqvist