How much do you weigh? This 3-year-old boy weighs 70kg!

Three-year-old Brazilian boy, Misael, was born a healthy 2.9kg but today, he weighs a staggering 70kg for his age and struggles to walk.

Doctors believe he may be suffering from Prader–Willi syndrome, a rare genetic condition characterised by a constant hunger and desire to eat. Children with the condition continue to feel hungry even after eating three to six times more than others of their age.

Symptoms of the syndrome may include a permanent feeling of hunger, which can lead to dangerous weight gain, reduced muscle tone and learning difficulties. Behavioral problems may also occur. There is no known cure for it yet, except treatments aimed at managing the symptoms.

Misael also suffers from an underactive thyroid - which can cause weight gain - and his parents say prescribed medication was not working.

His father told MailOnline: “Even taking him to the doctor or leaving the house with him is difficult. And when we walk down the street, people stop, want to take pictures with him, people say that they never saw [a boy] this size, people want to know how old he is, how much he weighs...”

 His behavioural problems, which include temper tantrums and stubbornness, pose another difficulty for his parents who are always forced to hire a private taxi during outings.