Children with a hearty appetite may be genetically predisposed to obesity, yet healthy eating habits could help to prevent weight gain, according to new British research.
With a third of British youngsters now overweight or obese, a research team from University College London wanted to find out why some children gain lots of weight and others remain effortlessly slim in the current environment, where there is a seemingly unlimited supply of palatable, affordable food.
“We’ve known for many years body weight is highly heritable which is surprising given that recent changes to the environment over the last 30 years have played a role in population weight gain,” said lead researcher Dr Clare Llewellyn.
How it can be both genetic and environmental is a paradox said Llewellyn; the gene pool can’t change in 30 years.
The study, using data of 10-year-old children in the 1990s, created an obesity risk score for each child to estimate their genetic susceptibility to obesity. The scores were examined to determine the correlation with the children’s satiety responsiveness and body fat accumulation.
“It could be the case that ‘obesity genes’ influence your weight because they are influencing your appetite so they indirectly influence your weight,” said Llewellyn, who is a lecturer at the Health Behaviour Research Centre.
Since 2007, genome-wide association studies have identified 30 genetic variants robustly associated with weight.
Llewellyn said that people inherit a higher or lower appetite by virtue of their genetic endowment, namely satiety sensitivity levels (SSL), so less sensitive people eat more.
The very satiety sensitive feel full quickly and find it easy to regulate their intake according to how much they actually need to eat.
The research team admit they can’t determine whether it’s possible to change an individual’s SSL but believe health professionals and child experts need to widen their outlook about tackling obesity and educate families and children about healthy eating habits.
“Historically health care professionals have focused on the quality of the food itself not the way people eat food. Of course, the quality of the diet itself is fundamentally important, but it’s also about being aware of how full you feel whatever you’re eating,” Llewellyn said.
She would like to see health visitors advising mothers to ensure the whole family sits down together at the table at dinnertime and eats at a reasonable speed. Also adopting an authoritative – firm but gentle – approach, refusing to give second helpings, and discouraging the family from eating in front of the TV would be beneficial.
“We know from experimental studies that people eat more when watching TV than when not. If you ask people to pay attention to when they’re full they tend to eat less,” she said.
The government is attempting to address childhood obesity with its “Healthy Child Programme”, but the report admits health professionals lack confidence in dealing with the issue. Parents of obese preschool children also find traditional approaches to obesity management unhelpful.
A Department of Health spokesperson said in an email: “The government is tackling childhood obesity head-on by giving primary schools £450 million to improve sport and help pupils become healthy and active.
“We have also invested an extra £3 million in Change4Life School Sports Clubs in areas with high childhood obesity and are working with the food industry through the Responsibility Deal to reduce calories and sugar in food and drinks. Our new food-labelling system will also help parents make healthier choices for their families.”
Researchers would like to see schools introducing healthy eating behaviour training into the curriculum.
Several studies from the United States have shown the positive value of such instruction.
Dr Susan Johnson from the University of Colorado, in Denver, taught pre-school children to become aware of their fullness signals when eating, resulting in them eating less than before.
Another one from 1977 found that when obese children were trained to put down eating utensils in between each mouthful of food they decreased their intake of food.
A British study, based at the Bristol Care of Childhood Obesity Clinic, also found success in training obese adolescents to regulate and slow down their eating speed with the use of a metronome-like device called a Mandometer.
More research is needed to explore satiety sensitivity.
“Is it when you eat you fill up and can’t eat anymore?” Llewellyn asks. Or is it the case that food become less rewarding when eating and the reward signal in the brain is switched off?
However, she said it may be the case that some children who appear to be low satiety sensitive are actually overeating because they get a greater reward from eating nice food, that is, comfort eating.