Abstract Overweight/obesity, caused by the ‘nutrition transition’, is identified as one of the leading risk factors for non-communicable mortality. The nutrition transition in developing countries is associated with a major shift from the consumption of staple crops and whole grains to highly and partially processed foods. This study examines the contribution of processed foods consumption to the prevalence of overweight/obesity in Guatemala using generalized methods of moments (GMM) regression. The results show that all other things remaining constant, a 10% point increase in the share of partially processed foods from the total household food expenditure increases the BMI of family members (aged 10 years and above) by 3.95%. The impact of highly processed foods is much stronger. A 10% point increase in the share of highly processed food items increases the BMI of individuals by 4.25%, ceteris paribus. The results are robust when body weight is measured by overweight/obesity indicators. These findings suggest that increasing shares of partially and highly processed foods from the total consumption expenditure could be one of the major risk factors for the high prevalence of overweight/obesity in the country. Copyright © 2009 John Wiley & Sons, Ltd.