An overweight youth in his early 20s is three times more at risk of developing cancer of either the oesophagus (food pipe) or upper stomach in adulthood, researchers have warned.The findings showed that those who are overweight at the age of 20 are nearly 60-80 per cent more likely to develop these cancers in later life, compared to those who maintained a healthy weight throughout life.Those who gained more than 20 kg during adulthood were also twice as likely to develop oesophageal cancer compared to people who had little weight change.Carrying excess weight can trigger long-term reflux problems and heartburn that can lead to cancer.It can also change the levels of sex hormones, such as oestrogen and testosterone, cause levels of insulin to rise, and lead to inflammation -- all of which are factors associated with increased cancer risk, the researchers said."The study highlights how weight gain over the course of our lives can increase the risk of developing these two cancer types, both of which have extremely poor survival rate," said lead author Jessica Petrick from the National Cancer Institute in Maryland, US. For the study, published in the British Journal of Cancer, the team pooled data from more than 400,000 people and analysed their reported height and weight at ages 20 and 50.The study highlighted the importance of keeping a healthy weight throughout life to reduce the risk of developing these cancers. Small steps like taking the stairs more often, keeping an eye on the quantity of food consumed and switching to sugar-free drinks are simple things we all can do to keep a healthy weight, the researchers suggested.