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She is just 10 months old, but baby Juanita Valentina Hernandez weighs the same as an average five-year-old.

While the youngster was a normal 6lb when she was born, she began to expand rapidly in size just weeks later.

She now tips the scales at 44lb (20kgs or just over three stone) and is undergoing tests to determine the cause of her surprise weight gain.

The average 10-month-old baby should weigh 19lb or 8.5kg, Tam Fry, Patron of the Child Growth Foundation, told MailOnline.

He said: 'Weight can vary with ethnicity, but regardless of that, this child is vastly, vastly overweight. It is tragic.'

Juanita's anxious mother, Sandra Franco, from Libano, Colombia, said she has no idea what has caused her daughter to balloon in size.

'When she was 15 days old she was already looking chubby, because she was born very thin,' she explained.

'Since then she's been gaining weight. Now she is 10 months old and I have realised she is morbidly obese.'

She added: 'Until now I haven't been able to treat her because I am unemployed and didn't have the money.'

Mr Fry explained there are various medical conditions which can cause rapid weight gain in children.

These include Prader-Willi syndrome, which causes a permanent feeling of hunger and can easily lead to dangerous weight gain.

Conditions such as Cushings sydrome - where high levels of the stress hormone cortisol can cause weight gain - and Beckwith-Wiedemann syndrome, known as an 'overgrowth syndrome' can also cause children to expand in size rapidly.

Last month Colombian charity Gorditos de Corazon - Chubby Hearts - brought Juanita to the capital, Bogota, where a team of specialists began treatment.

Charity founder Salvador Palacio Gonzalez has made it his mission to tackle a growing obesity problem, which increasingly is affecting children.

Juanita is the third baby he has seen in the last year who weighs more than 20kg.

Last year the charity helped the families of obese babies Santiago Mendoza and Mayra Caicedo who had a combined weight of 41kg (90lb or more than six stone).

Speaking previously about the epidemic in his country, Salvador said: 'Thousands of children in Colombia - and millions around the world - suffer with obesity.

'From Colombia we have formed an international alliance to help people who are overweight.'

Despite being less than one year old, young Juanita faces a bleak future if her rapid weight gain cannot be controlled.

The charity says it is crucial to intervene before the age of one in order to prevent illnesses associated with obesity becoming a critical health risk.

The most immediate risk of Juanita being so overweight is that she may develop type 2 diabetes within two or three years, Mr Fry told MailOnline.

He said: 'We are already seeing children aged four with this condition, which can lead to heart disease in the teenage years.'

'Overweight children and teenagers are more likely to become overweight or obese adults. It is an extremely difficult cycle to break.'

Juanita's mother added: 'To all mothers that have babies like this, please take care of our children if we don't want them to get sick.

'Please don't let them die from one of these diseases.'