Sex Differences in Blood Pressure Appears As Early As Adolescence, With Girls Faring Worse
Posted by on November 6, 2015 - 12:50pm

The female hormone estrogen is known to offer protection for the heart, but obesity may be taking away that edge in adolescent girls. Research from the University of California at Merced finds that although obesity does not help teens of either gender, it has a greater impact on girls’ blood pressure than it does on boys’. In a study of more than 1,700 adolescents between 13 and 17 years old, obese boys were 3.5 times more likely to develop elevated systolic blood pressure (SBP) than non-obese boys, but similarly obese girls were 9 times more likely to develop elevated systolic blood pressure than their non-obese peers.

Systolic blood pressure, which is represented by the top number in a blood pressure reading, is the amount of force that blood exerts on blood vessel walls when the heart beats. High systolic measurements indicate risk for heart disease and stroke. Rudy M. Ortiz, PhD, Associate Professor of Physiology and Nutrition and his team obtained their data by direct measurements during the school district’s health surveys and physicals to assess the teenagers’ systolic blood pressure (SBP) against two health indicators: body mass index (BMI), which was categorized as normal weight, overweight, or obese, and blood pressure, which was categorized as normal, pre-elevated, or elevated. The researchers found that the teenagers’ mean BMI was significantly correlated with mean SPB for both sexes when both BMI and blood pressure assessments were used. They also found a significant correlation between BMI and SBP as a function of blood pressure, suggesting that the effect of body mass on SBP is much greater when it is assessed using blood pressure categories. “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,” said Dr. Ortiz. An odds ratio analysis revealed that obese boys were 2 and 3.5 times more likely to develop pre-elevated and elevated SBP, respectively, than boys who were normal weight. Obese girls were 4 and 9 times more likely to develop pre-elevated and elevated SBP, respectively, than girls who were normal weight.

According to Dr. Ortiz, the results do not bode well for obese teens later in life, especially for the girls. “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].” As for why obesity has a greater impact on SBP in girls than in boys, Dr. Ortiz has a hunch. “This may be where physical activity comes into play. We know, for example, that obese adolescent females participate in 50 to 60% less physical activity than boys in the population surveyed.”

It's important to take steps to prevent obesity at its first onset--for both adolescent boys and girls. Being active and eating healthy foods are great initial steps towards healthy living!

Teens, obesity and blood pressure, girls fare worse
Posted by on October 31, 2011 - 12:37pm

Gender Differences in Blood Pressure Appears As Early As Adolescence, With Girls Faring Worse The female hormone estrogen is known to offer protection for the heart, but obesity may be taking away that edge in adolescent girls. New research from the University of California at Merced finds that although obesity does not help teens of either gender, it has a greater impact on girls’ blood pressure than it does on boys’. In a study of more than 1,700 adolescents between 13 and 17 years old, obese boys were 3.5 times more likely to develop elevated systolic blood pressure (SBP) than non-obese boys, but similarly obese girls were 9 times more likely to develop elevated systolic blood pressure than their non-obese peers. Systolic blood pressure, which is represented by the top number in a blood pressure reading, is the amount of force that blood exerts on blood vessel walls when the heart beats. High systolic measurements indicate risk for heart disease and stroke. Rudy M. Ortiz, PhD, Associate Professor of Physiology and Nutrition and his team obtained their data by direct measurements during the school district’s health surveys and physicals to assess the teenagers’ systolic blood pressure (SBP) against two health indicators: body mass index (BMI), which was categorized as normal weight, overweight, or obese, and blood pressure, which was categorized as normal, pre-elevated, or elevated. The researchers found that the teenagers’ mean BMI was significantly correlated with mean SPB for both sexes when both BMI and blood pressure assessments were used. They also found a significant correlation between BMI and SBP as a function of blood pressure, suggesting that the effect of body mass on SBP is much greater when it is assessed using blood pressure categories. “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,” said Dr. Ortiz. An odds ratio analysis revealed that obese boys were 2 and 3.5 times more likely to develop pre-elevated and elevated SBP, respectively, than boys who were normal weight. Obese girls were 4 and 9 times more likely to develop pre-elevated and elevated SBP, respectively, than girls who were normal weight. According to Dr. Ortiz, the results do not bode well for obese teens later in life, especially for the girls. “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].” As for why obesity has a greater impact on SBP in girls than in boys, Dr. Ortiz has a hunch. “This may be where physical activity comes into play. We know, for example, that obese adolescent females participate in 50 to 60% less physical activity than boys in the population surveyed.”

Gender-specific differences in obesity
Posted by on August 8, 2011 - 11:24am

Why are some people obese while others are lean? Obese people must make poor eating choices, but could there be a physiological basis for those poor choices? A new study reveals that obese and lean people make decisions about short-term versus long-term rewards differently and have physical differences in their brains. Surprisingly, some of these behavioral and physical differences are found only in women.

An article recently published in the journal Frontiers in Human Neuroscience tested how lean and obese people relate to rewards using a simple card game. In this game, participants had to choose between two decks of cards. One deck provided large immediate rewards but overall losses in the long-term. This deck was meant to parallel the immediate reward of eating and the long-term negative effect of overeating on body weight. The other deck gave subjects smaller immediate rewards but was more advantageous in the long run. This deck represented healthier eating choices – less fulfilling immediately but more beneficial in the long term.

The researchers found that obese women choose immediate rewards more often than lean women. In fact, as the body mass index or BMI of the subjects increased, so did the number of times that they chose from the deck that provided large immediate rewards.

Additionally, as they played this card game over time lean women altered their choices and started to choose more cards from the deck that was advantageous in the long run. In contrast, obese women did not change their decision-making over time and continued to choose just as many cards from the deck that provided large immediate rewards but overall losses as the game progressed.

Remarkably, these behavioral differences between lean and obese participants were limited to women. No difference was seen between lean and obese men.

To investigate the possible basis of the behavioral differences between subjects, the brain structure of lean and obese men and women was examined using magnetic resonance imaging or MRI. Differences in brain structure between obese and lean people have been reported previously. This study found additional differences that were only present in obese versus lean women and not men.

Both the behavior and brain structure of the obese women observed in this study suggest that obese women might make poor eating choices because they are more sensitive to rewards and are driven more by habit-like behavior rather than goal-directed behavior. It is not known, however, if the alterations in brain structure in obese individuals are themselves the cause of obesity and overeating behaviors, or if the alterations are the effect of obesity-related behaviors.

The differences in behavior and brain structure between lean and obese women uncovered in this research could be important for the development of gender-specific treatments for obesity.