Do you have a sibling? Then your chances of having a healthy weight is high

A study from Germany says the BMI of an only child is likely to be far higher than children with siblings.

ByChetana Belagere

Published Jul 20, 2022 | 4:51 PM Updated Jul 20, 2022 | 6:33 PM

A study from Germany says BMI of only child to be far high than those with siblings

Your chances of being of healthy weight are high if you have a sibling or if you are the younger child, according to a new study from Germany. The research by LIFE Child (Leipzig Research Centre for Civilization Diseases) was published in PLOS ONE.

In the first of it’s kind intra-family study, the researchers had a sample of 1,932 children who were a mix of first, second, third or later born, only children, and twin children. Pre- and post-natal factors like mother’s age, pre- and post-pregnancy weight gain, duration of breastfeeding, as well as the child’s physical activity were taken into consideration for the study.

A study from Germany says BMI of only child to be far high than those with siblings

High BMI in people with obsesity/creative commons

The study noted that nearly 90 percent of children with obesity by age three will be overweight in early adulthood, making it mandatory to form good habits in early childhood to prevent obesity.

“Therefore, there is an urgent medical need to identify the precise risk factors for the development of obesity and to give recommendations to families at high risk,” the authors were quoted as saying in the study.

Same family, different health status

The study claims that though siblings living together in a family have similar backgrounds and grow up in the same social environment, have similar eating habits and level of physical activity until adolescence, it found that each family member has an individual health status. “This is reflected in differences in BMI between siblings,” say the authors of the study.

However, though some previous studies have dwelt on these points, this study says that there is lack of knowledge on the reasons as to what causes BMI differences between siblings.

What did the study find?

Until the age of six years, the first, second, third or later born, and twins, had no significant difference in their BMI between them and those who were only children. However, at age 7-18 the BMI was significantly higher in only children than in siblings.

Having a sibling reduces risk of obesity

Having a sibling reduces risk of obesity/creative commons

“In early childhood up to age 11, children with siblings had lower BMI, particularly first-and second-born children. Of all siblings, third-or-later born children had the highest BMI-SDS, which is inline with earlier studies,” the study stated in the journal.

Only child and weight gain

According to the study, they could establish a negative correlation between BMI and having no siblings. It was observed that single children gained more weight, especially in later childhood. While the authors quote other studies showing that single children are at risk of obesity, they say, “Children with siblings generally have higher activity levels, especially with older siblings. They can also act as additional caregivers which promotes active play. More siblings, more activities are seen and similarly, the study found a general decrease in activity levels in families having fewer siblings and having lowest activity levels in a family with only one child,” the authors noted.

The study also found that third or later born children were most active and the only children were in the least active group.

Limitations of the study

The study lists its limitations and says the “results may be biased by factors that were not directly observed”. Among the limitations were: Not looking into smoking habits during pregnancy, premature children, children’s eating habits after breastfeeding were not studied.

The influence of step siblings and caregivers on children’s eating habits, influence of siblings on a child’s physical and eating habits, and socio-economic status were also not considered.

What do our doctors think?

Having a sibling reduces risk of obesity

Having a sibling reduces risk of obesity/creative commons

Dr Sanjay Kumar, Paediatrician, Shanti Hospital, Bengaluru, says, “When you have a sibling it is like having a ready playmate. At any given time you have siblings to engage in some kind of activities. Also, it is very natural that food gets distributed in the family, choice of food then is mostly done by the parents when there are two or more children,” explains the doctor.

Paediatricians say that teaching healthy habits like having a set  time within the family for physical activity, strict nutrition, and good sleeping habits is a way in which parents or caregivers of a single child can work towards decreasing obesity.

Having a sibling encourages more play time

Having a sibling encourages more play time/creative commons

However, not all doctors quite agree with the study. Dr Gunda Srinivas, Consultant- Pediatric Emergency & Pediatrics, Aster RV Hospital says, “I don’t agree with this entirely. Yes, there are such families. There are also families with both siblings having higher BMI. There can be strong genetic reasons, unhealthy eating practices of the whole family, sedentary lifestyle and increased screen-time of both siblings, or behaviour being learnt by observing the other sibling. In such cases, being siblings, in fact, could pose a higher risk of having higher BMI because of the similar family environment and practices being followed in the family.”

However, Dr Narahari B, Senior Paediatrician, Niloufer Hospital, Hyderabad, agrees that “family dynamics” plays an important role in controlling obesity. He says that sometimes parents have a tendency to constantly feed their children and feel the child’s desire for some other materialistic thing can be silenced with food. This can lead into a dysfunctional relationship with food, and lead to complications in adulthood, he explains.

Family dynamics, food habits important to maintain healthy weight

Family dynamics, food habits important to maintain healthy weight/Creative Commons

Meanwhile, Dr Jothydev Kesavadev, Diabetologist from Kerala, says there is a need for more such associations as the incidence of children getting diagnosed with diabetes is on the rise.

“We are shocked to see when we do screening of children whose either one or both parents have Type 2 Diabetes. The numbers are high. Such correlations can may be bring out newer approaches to handling obesity which is soon going to become another epidemic.”

Who can be called an obese?

Any adult with a body mass index (BMI) over 30 is considered obese. In Children, though obesity is not exactly measured by BMI, it is done by comparing other children of same age and sex. Those in 95th perecentile of BMI are considered obese, according to the Centers for Disease Control and Prevention.