While we know a lot about the problem of childhood obesity from studying the heights and weights of groups of children at different ages, less is known about how obesity develops by studying the same child over a long period of time.
Our study of a representative sample of more than 13,000 children throughout the UK looked at whether children between the ages of three and 11 were overweight and obese. These children were all born between 2000 and 2002 and have been measured and weighed at four points so far (age three, five, seven and 11) as part of the ongoing Millennium Cohort Study.
Obesity on the increase
At age 11, 65% of children were not overweight or obese, 15% were overweight and 20% were obese. That means that an alarming 35% of the nation’s 11-year-olds could face a health risk because of their weight. What is also striking is how this has grown between the ages of seven and 11. At age seven, around 25% of children were classified as either overweight or obese, but by the age of 11 this figure had increased by around 10%.
This may be because 11-year-olds are experiencing more freedom in their food choices and may also be moving away from physical play to more sedentary activities. More research is needed to understand why this age seems to be such a critical period.
We found that only half of children were a healthy weight at all of the ages they were measured, while 4% of children have consistently been overweight and 1% of children have consistently been obese. Notably, 44% of children changed their weight status at some point in the study.
Although we found evidence that those children who were overweight were more likely to be moving into the obese category throughout their childhood, there are also a small proportion of children with healthy weights aged seven who became overweight and obese by age 11. This highlights the need for all parents to be aware of their child’s weight as they grow older.
Following in parents’ footsteps
So which children are at the most risk of overweight and obesity at age 11? Our research took account of a number of factors previously associated with childhood obesity. Clear associations were found between weight status and parental education. The highest levels of obesity were observed among children whose parents had no educational qualifications, and the lowest levels were found in children of degree-educated parents. Education might enable and empower parents to develop more effective attitudes, lifestyles and health behaviours which may be an important influence on childhood obesity.
We also found a clear association between the weight of children and their mothers. Children whose mothers are not overweight are the least likely to be overweight or obese themselves. The children of obese mothers have the highest levels of being overweight and obese.
Children will learn and copy the behaviours of their mothers, and there is evidence that the formation of dietary habits in young children is greatly influenced by the behaviour and attitudes of their parents. Addressing weight issues in families, rather than just children, may be the best way to tackle the childhood obesity problem.
Obesity is a major concern for children’s health. Overweight children are at increased risk of becoming overweight adults and being overweight or obese is associated with an elevated risk of health problems such as asthma, cardiovascular disease and type 2 diabetes. Childhood overweight is also associated with psycho-social problems and depression and can have a major and enduring influence on an individual’s life.
At age 11 the children answered a series of questions about their happiness and self-esteem. The obese children were the least likely to be “completely happy with the way they look”, compared to those who were either not overweight or overweight. They were also more likely to say they were “not happy at all with with the way they look”.
Asked about how happy they were with their life as a whole, obese girls were less likely to say they were “completely happy”, although there was no significant association for boys. Overweight and obese children also demonstrated higher rates of low self-esteem when responding to questions such as “I am a person of value” and “I feel I have a number of good qualities.”
Understanding these associations is complex because low self-esteem and unhappiness may be factors contributing to a child putting on weight, rather than occurring as a consequence of it. But it’s clear that many children about to enter their teenage years are suffering both the negative health effects of obesity and its psychological impacts.