A 49 year old man and a 44 year old woman, from King’s Lynn in Norfolk, were questioned by officers over the child’s care.
Police said intervention at this level was “very rare” and only occurred where other attempts to protect the child had been unsuccessful.
The Sun reported the couple’s 11-year-old son is 5ft 1in (1.5m) and 15 stone, with a body mass index (BMI) of 41.8.
A spokeswoman added police were working with health and social services. The couple were arrested in March on suspicion of child neglect and cruelty under section 1 of the Children’s Act 1933.
Public Health England report latest figures, for 2012/13, show that 18.9% of children in Year 6 (aged 10-11) were obese and a further 14.4% were overweight.
The parents have been released on bail.
Sources:
http://www.bbc.co.uk/news/uk-england-suffolk-27730696
http://www.noo.org.uk/NOO_about_obesity/child_obesity