Table 1 Participant eligibility, inclusion and exclusion criteria

Inclusion

 Intellectual disability

Any level of intellectual disability

 Age

Adults ≥18 years old (there is no upper age limit, in keeping with the GCWMS and specialist intellectual disability health services in NHS GGC)

 Weight status

BMI ≥30 kg/m²

 Ambulatory

Ability to walk (with or without a walking aid) for 10 min at a time based on self/carer report

 Diet

Not currently on a prescribed or restricted diet, e.g. for phenylketonuria or diabetes

 Weight stability

No intentional weight loss >3 kg over the previous 3 months

Exclusion

 Genetic intellectual disability

Participants with Prader Willi syndrome, Cohen syndrome or Bardet-Biedl syndrome as they require specific support to lose weight

 Research

Currently taking part in any other research study

 Medication

Taking medication; either prescribed or over the counter, designed for weight loss

 Pregnancy

Individuals who are pregnant will be excluded from the study and anyone who conceived during the study will be excluded.