Babies that have big appetites are usually seen as a healthy sign, but scientists say it may indicate they are more predisposed to obesity later on in life.
Infants that display two key aspects of appetite grow unusually rapidly up to the age of 15 months, research has shown.
This potentially increases their chances of becoming obese children, according to experts.
A second study found that 10-year-olds with a lower satiety response, making them less likely to stop eating when they feel full, were genetically more susceptible to obesity.
Satiety responsiveness (SR) was one of the measurements taken to monitor appetite in infants.
Scientists studied data from non-identical same sex twins born in the UK in 2007 who had different levels of SR and food responsiveness (FR), the urge to eat when seeing or smelling tempting food.
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These kids are even more likely to become obese adults.
According to the Center For Disease Control and Prevention (CDC), 17% (or 12.5 million) of kids and adolescents aged 2 - 19 years in the United States are now obese.
The rate among this age group increased from 5% to 10.4% in 1976-1980 and 2007-2008.
Obese kids are more likely to also be obese as adults, which puts them at risk for heart disease, diabetes, and more adult health problems.
CDC data shows that there was an increase in the pervasiveness of obesity in the American population between 1976-1980 and then again from 1999-2000, the prevalence of obesity increased.
Obesity in low-income 2- to 4-year-olds rose from 12.4% of the population in 1998 to 14.5% in 2003 but increased to 14.6% in 2008.
And only 25% of kids in this age group get the recommended three daily serving of vegetables. One way to make sure your child gets the amount of fruit and vegetables that they need is to serve them at every meal.
In 2011, only 29% of high-schoolers in a survey participated in 60 minutes of physical activity each day, which is the amount recommended by the CDC. It’s best for kids to get three different types of exercise: aerobic activity, like walking or running, muscle strengthening activities like push-ups or pull-ups and bone strengthening activities like jumping rope.
High blood pressure, diabetes and other cardiovascular issues have been previously tied to obesity. But a 2013 study found that obesity also puts kids at risk for other health issues such as ADHD, allergies and ear infections.
This number was documented by the FTC in 2008. According to the APA, there are strong associations between the increase in junk food advertising to kids and the climbing rate of childhood obesity.
Within pairs, the baby that was more food responsive or less satiety responsive than its twin grew faster.
At 15 months old, both traits separately caused a twin to be around two pounds heavier than its sibling.
Lead scientist Professor Jane Wardle, from the Health Behaviour Research Centre at University College London, said: "Obesity is a major issue in child health.
"Identifying factors that promote or protect against weight gain could help identify targets for obesity intervention and prevention in future. These findings are extremely powerful because we were comparing children of the same age and same sex growing up in the same family in order to reveal the role that appetite plays in infant growth.
"It might make life easy to have a baby with a hearty appetite, but as she grows up, parents may need to be alert for tendencies to be somewhat over-responsive to food cues in the environment, or somewhat unresponsive to fullness. This behaviour could put her at risk of gaining weight faster than is good for her."
The findings appear in the journal JAMA Pediatrics alongside a second study by another UCL team from the Health Behaviour Research Centre.
Genetic data from 2,258 children aged 10 were used to create scores for susceptibility to obesity. The "polygenic obesity risk" (PRS) ratings were based on the number of high-risk variants among 28 obesity-related genes in each child.
"As expected, we found that children with a higher PRS score were likely to have larger BMI (body mass index) and waist circumference," said Dr Clare Llewellyn, who led the research. "But more importantly, we also found that these children were more likely to have low satiety responsiveness.
"This suggests that satiety responsiveness could be targeted for pharmacological and behavioural interventions, to prevent or treat obesity."For example, children with lower satiety sensitivity could be taught techniques that might improve their fullness signals when eating, such as slowing their eating speed. Another approach might be to provide better advice to parents and children about appropriate portion sizes, limiting access to 'second helpings' and ensuring tempting treats are out of sight between meals."