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Closer - The home of longitudinal research

Obesity

Two middle aged women enjoy an exercise classLongitudinal population studies gather information on individuals’ physical development and growth at multiple points in time, making them a unique resource for the study of overweight and obesity in childhood and adulthood.

They are crucial sources of evidence as they allow researchers to understand more about the predictors and prevalence of obesity over the life course. Comparing different studies allows us to track the evolution of the obesity epidemic across generations. 

Key messages

  • Previous policies to reduce childhood obesity have not been adequate and existing policies are unlikely to be either. There is a need for measures that focus on societal factors and the food industry, rather than individuals or families. 
  • CLOSER funded research into obesity across five generations tracked increases in body mass index (BMI) for more than 56,000 people born in the UK from 1946 to 2001. The findings showed that children born since 1990 are up to three times more likely than older generations to be overweight or obese by age 10. 
  • Since 1946, every generation has been heavier than the previous one. People are also becoming overweight or obese at an increasingly younger age. Half the men of the 1946 generation were overweight by the time they were 41 years old, compared to age 30 for men born in 1970. Half the women born in 1946 were overweight by age 48, compared to 41 for the 1970 generation. 
  • Research using data from longitudinal population studies has shown that 5-year-olds from the poorest households are twice as likely to be obese compared to children from better-off homes. By age 11, they were almost three times as likely to be dangerously overweight. 
  • Early years interventions may be more effective than those in later life, as would policies that target the local environment – including access to healthy foods and options for physical activity. This approach may be more effective than relying solely on individuals to change their behaviours, since people with fewer resources are often highly constrained in their choices. 

Evidence