Obesity

Longitudinal evidence has demonstrated that people who are overweight or obese face a higher risk of health problems. For example, research based on the MRC National Survey of Health and Development (1946 cohort) found that excessive weight gain during any period of adulthood was associated with higher blood pressure at age 53. People who became overweight in their early adult years were more likely to have higher blood pressure in their early-50s than those who gained weight later.

Analysis of the 1946 cohort has also shown that adults who are overweight or obese are at a greater risk of conditions associated with heart disease, including type 2 diabetes, high blood pressure, and high cholesterol levels. The researchers found that the risk increased the longer people were overweight for.

Data from the Millennium Cohort Study (MCS) revealed that 16 per cent of UK children born in 2000-2001 were overweight by age 5, and a further 5 per cent were obese. Levels of overweight and obesity varied significantly by UK country, with children in Northern Ireland most likely to be overweight or obese (25 per cent) and those in England least likely (21 per cent).

Analysis of the MCS has also shown that levels of childhood obesity differ with gender and ethnicity. Researchers found that Black children were at the highest risk of being overweight or obese both at ages 3 (30 per cent) and 5 (36 per cent). This compares to 10 per cent of Indian children who were overweight or obese at age 3, and 19 per cent at age 5. While there was no gender difference at age 3, 23 per cent of girls were either overweight or obese by age 5 compared to 19 per cent of boys. In addition, the risk of being overweight or obese at age 5 was linked to lower maternal socioeconomic status and educational qualifications, and reduced household income.

There is mixed evidence on the impact of being breastfed on obesity in childhood and adulthood. Some studies have suggested that breastfeeding protects against obesity. For example, researchers using the MCS found that children were more likely to be overweight at age 3 if they were never breastfed, and if they were introduced to solid foods before they were 4 months old.

However, an analysis of the 1958 National Child Development Study found no effect of breastfeeding on body mass index (BMI) once other background factors, such as social class and mother’s weight, had been taken into account.

A study of data from Southampton Women’s Survey (SWS) revealed that children whose mothers gain excessive weight during pregnancy were more likely to be overweight at birth and in early childhood. They had an average of 7 per cent more fat mass at birth than children whose mothers gained an adequate amount of weight in pregnancy. At age 6, they had 10 per cent more fat mass.