To study the magnitude and predictors of underweight, incident underweight and recovery from underweight among rural Indian adults.

Prospective cohort study. Each participant’s BMI was measured in 2008 and 2012 and categorized as underweight (BMI<18·5 kg/m2), normal (BMI=18·5–22·9 kg/m2) or overweight/obese (BMI ≥23·0 kg/m2). Incident underweight was defined as a transition from normal weight or overweight/obese in 2008 to underweight in 2012, and recovery from underweight as a transition from underweight in 2008 to normal weight in 2012. Bivariate and multivariable logistic regression analyses were employed.

The Birbhum Health and Demographic Surveillance System, West Bengal, India.

Predominantly rural individuals (n 6732) aged ≥18 years enrolled in 2008 were followed up in 2012.

In 2008, the prevalence of underweight was 46·5 %. From 2008 to 2012, 25·8 % of underweight persons transitioned to normal BMI, 12·9 % of normal-weight persons became underweight and 0·1 % of overweight/obese persons became underweight. Multivariable models reveal that people aged 25–49 years, educated and wealthier people, and non-smokers had lower odds of underweight in 2008 and lower odds of incident underweight. Odds of recovery from underweight were lower among people aged ≥36 years and higher among educated (Grade 6 or higher) individuals.

The current study highlights a high incidence of underweight and important risk factors and modifiable predictors of underweight in rural India, which may inform the design of local nutrition interventions.