Institute of Epidemiology & Health Care


The Obesity Research Group

Obesity research group

The Obesity research group is interested in establishing the causes of obesity across the lifespan, developing and testing behavioural interventions for the prevention and management of obesity in children and adults, and evaluating obesity-related public health initiatives. We also study energy balance behaviours, including eating behaviour, physical activity and sleep. We have expertise in behavioural and psychometric measurement, epidemiology, behaviour genetics, intervention design, trial management and qualitative research. 


This group is led by Dr Clare Llewellyn (c.llewellyn@ucl.ac.uk)

Group members

Research staff: 

Dr Clare Llewellyn
Dr Pippa Lally
Dr Andrea Smith
Dr Ali Fildes

Zeynep Nas - Postdoctoral research fellow
I’m a postdoctoral research fellow working with Dr Clare Llewellyn and the wider Gemini study team. My research focus will be on appetite, eating behaviours as well as parental feeding practices using twin model fitting as well as molecular genetic approaches.

Alice Kininmonth – Postdoctoral Fellow
From January 1st 2022, I will be working as a Postdoctoral Fellow in the Obesity group on the APPETItE project and also involved in Gemini.

Sara Esser – Research assistant
I am currently working on two projects: 1. The NIHR Obesity Policy Research Unit (OPRU) and 2. Development of a digital intervention to promote healthy growth during the first 2 years of life.

PhD students: 

Lisa Heggie
PhD project title: Nutritive and non-nutritive sweeteners and their associations with weight and diet in children
PhD description: 
Nutritive, low- and no-calorie sweeteners are increasingly prevalent within modernised diets, driven largely by abundant food availability and choice. Genetically determined variation in taste sensitivity to bitterness may also influence intake of low- and no-calorie sweeteners at individual level, as many sugar substitutes are typically bitter in flavour; but to date, the genetic and environmental influences on intake have never been examined. Low- and no-calorie sweeteners are often substituted for sugar to reduce calorie intake and help maintain a healthy weight or prevent excessive weight gain, however, very little is known about the prospective association between intake of these sugar substitutes and weight gain trajectories in early childhood. In particular, there is some concern that consumption of low- or no-calorie sweeteners during early childhood may ‘programme’ sweet preference, but currently, there are no large prospective studies to test this hypothesis. In fact, there is no descriptive population-based UK data of intakes of low- and no-calorie sweeteners in early childhood.

A better understanding of both the genetic and environmental influences of habitual sweetener and sweetness enhancer intake during the key developmental stages of toddlerhood and childhood, and the long-term effects of intake on early weight gain and developing taste preferences is crucial for the development of public health policy surrounding food safety and obesity. This PhD will be the first large-scale exploration of nutritive, low and no-calorie sweeteners in early childhood, and will support a large European Commission-funded programme of research into the long-term health effects and safety of these products.
Research profiles:
Twitter: https://twitter.com/LisaaHeggie
Google Scholar: https://scholar.google.com/citations?view_op=list_works&hl=en&authuser=1&user=uedUFKMAAAAJ
SWEET profile: https://sweetproject.eu/meet-lisa-heggie-newest-member-of-wp-4/

Kristiane Tommerup
Kristiane’s PhD research focuses on exploring genetic, social, and behavioural risk factors for weight development across infancy. She uses data from the Gemini Twin Study to better understand how socioeconomic, behavioural, and genetic factors are related to and interact to shape weight development right from the very start of life. Prior to starting her PhD, Kristiane was a Research Assistant for the NIHR Obesity Policy Research Unit (OPRU) and completed her MSc in Health Psychology at UCL. 

Alex Rhodes 
Project title: Developing an app-based intervention to encourage and support expectant parents to develop healthier dietary and physical activity habits.
Pregnancy is a significant life change which can prompt the re-evaluation of health behaviours. A healthy eating and physical activity intervention targeting expectant couples could help to reduce rates of excessive gestational weight gain and build better lifestyle behaviours for family life. The intervention will draw on habit theory and the COM-B model of behaviour change and use a person-based approach in its development. It will sit within Baby Buddy, the free, NHS-approved pregnancy and parenting app from UK charity Best Beginnings.

Francesca Bentivegna 
Project title: Appetite, self-regulation, and the development of binge-eating behaviours: nature via nurture
I have recently started as a PhD student in the Energy Balance and Obesity research group, and my primary supervisor is Dr Clare Llewellyn. The aim of my project is to identify if food approach appetitive traits and self-regulation are risk factors for the onset of binge-eating symptoms using large population-based samples. Also, I aim to understand the genetic contributions to (and their interactions in) this relationship and to compare the findings across multiple population cohorts, including the Gemini twin study.


Ongoing PhD projects

  • Reducing calorie intake among working adults: Investigating the use of pre-ordering and substitution suggestions to reduce calories consumed in workplace canteens (Sarah Breathnach)
  • Developing an app-based intervention to encourage healthy eating, physical activity and weight management in pregnancy (Alexandra Rhodes)
  • Exploring the impact of the early obesogenic home environment on appetite and weight development during childhood (Alice Kininmonth

Ongoing projects

Completed PhD projects

Completed projects

Publications - Clare Llewellyn

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