How are children’s lives affected now?

Children with learning disabilities are at increased risk of obesity, which also increases their chances of developing other serious health conditions later in life, such as diabetes and heart disease.

“Some children will have rare genetic conditions that lead to both severe obesity and learning disabilities,” says Dr Legg. “Many still do not have a molecular diagnosis, which can have a significant impact on their families – causing uncertainty about the future, limiting access to treatments and clinical trials, and making it harder to access additional support.”

The co-occurrence of learning disabilities and severe obesity suggests they may have shared origins in brain development – particularly the hypothalamus, which plays a critical role in regulating body weight, behaviour and learning.

“We need to identify the root causes of learning disabilities and severe obesity to understand why these conditions often occur together – and how disruptions in brain development can lead to these problems,” explains Dr Legg.  

How could this research help?

Dr Legg has studied 2,000 children with both severe obesity and learning disabilities without a diagnosis, identifying changes in four genes implicated in the development of the hypothalamus.

“I now plan to study the effects of these gene changes in laboratory-grown cells to determine whether they disrupt protein function and nerve cell development,” says Dr Legg. 

He will also carry out detailed clinical assessments in children with these gene changes and family members to identify any other related problems, such as sleep problems and behavioural challenges – and search for other individuals with similar genetic changes.

“Our findings could lead to new diagnoses for some children with learning disabilities and severe obesity, potentially ending a ‘diagnostic odyssey’ for their families that may have lasted years or decades,” says Dr Legg. “In the longer term, this knowledge could support the development of new targeted treatments that can address the root causes of these conditions.”

Research Training Fellowships:

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References

1. Mencap. How common is learning disability in the UK? https://www.mencap.org.uk/learning-disability-explained/research-and-statistics/how-common-learning-disability [website accessed 24 March 2026]
2. Emerson E, Robertson J, Baines S, Hatton C. Obesity in British children with and without intellectual disability: cohort study. BMC Public Health. 2016 Jul 27;16:644