Being glued to your smartphone could trigger a heart attack, diabetes or even cancer, warns new research.
A study of more than 1,000 students found those who used it at least five hours a day were 43 per cent more likely to be obese.
They were also twice as prone to a host of habits that raise the risk of cardiovascular disease and other potentially fatal illnesses.
These included gorging on fast food, sweets and snacks, guzzling fizzy drinks and not getting enough exercise.
Lead author Dr Mirary Mantilla-Morron, a physiotherapist at Simon Bolivar University, Barranquilla, Colombia, said the devices are fuelling unhealthy lifestyles.
They are now such a key part of life and entertainment, particularly for young people, that they are making us lazy.
This can also lead to painful conditions that affect the muscles and joints - such as arthritis.
Dr Mantilla-Morron said: "Spending too much time in front of the smartphone facilitates sedentary behaviours, reduces the time of physical activity, which increases the risk of premature death, diabetes, heart disease, different types of cancer, osteoarticular discomfort and musculoskeletal symptoms."
Her findings were based on 700 female and 360 male undergraduates at the university with an average age of 19 and 20, respectively.
She told a meeting of the American College of Cardiology in Cartagena, Colombia: "The results of this study allow us to highlight one of the main causes of physical obesity, a risk factor for cardiovascular disease.
"We have also determined that the amount of time in which a person is exposed to the use of technologies - specifically prolonged cell phone use - is associated with the development of obesity."
More than a quarter (26 per cent) of the subjects who were overweight and almost one-in-twenty (4.6 per cent) who were obese spent more than five hours using their device.
Dr Mantilla-Morron, a cardiac pulmonary and vascular rehabilitation specialist, said: "It is important the general population know and be aware that, although mobile technology is undoubtedly attractive for its multiple purposes, portability, comfort, access to countless services, information and entertainment sources, it should also be used to improve habits and healthy behaviours."
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