First-borns may have a greater body mass index than second-borns

6 February 2014        

Waist measurement

Children born first into their family are more likely to have a greater body-mass index (BMI) and lower sensitivity to insulin than their younger siblings, researchers have suggested.

The researchers at the University of Auckland studied data from overweight middle-aged men, between the ages of 40 and 50, to assess whether birth order affects metabolism and body composition. The results found that first-born men were 6.9kg heavier and had a greater BMI (29.1 versus 27.5) than second-borns and insulin sensitivity was 33% lower in the older group. Insulin is a hormone which controls the level of glucose in your blood.

If your body becomes less sensitive to insulin, it can mean much higher levels of glucose in your blood and lead to type two diabetes. Those who are diabetic are much more likely to develop cardiovascular disease.

Carrying extra weight around can not only increase your risk of cardiovascular disease.

Christopher Allen, our Senior Cardiac Nurse said: “Carrying extra weight around can not only increase your risk of cardiovascular disease, but as this study points out, it can also affect how sensitive your body is to insulin. By having lower insulin sensitivity, this increases your risk of developing type two diabetes.

“It’s also important to note where you carry your weight. People who carry more fat around their middle are more likely to be resistant to the insulin their body is producing. If you’re concerned about your weight, have a chat to your GP – and if you’re over 40, make sure you take advantage of your free NHS health check.”