Obesity is a complex condition with biological, genetic, behavioral, social, cultural, and environmental influences. For example:

  • Individual behaviors and environmental factors can contribute to excess caloric intake and inadequate amounts of physical activity. The current high rates of obesity have been attributed to, in part, increased snacking and eating away from home, larger portion sizes, greater exposure to food advertising, limited access to physical activity opportunities, and labor-saving technological advances (Duffey & Popkin, 2011; Piernas & Popkin, 2011; Powell et al., 2011; Sallis & Glanz, 2009).
  • Certain medical conditions (e.g., polycystic ovary syndrome) and prescription drugs (e.g., steroids, anti-depressants) can cause weight gain.
  • Recent evidence suggests that inadequate sleep, prenatal and post-natal influences (e.g., maternal pre-pregnancy weight status, maternal smoking during pregnancy), chemical exposure, and stress may affect energy balance or obesity risk (Gore et al., 2015; Gundersen et al., 2011; Knutson, 2012; Shlisky et al., 2012; Weng et al., 2012).
  • Race-ethnicity, gender, age, income, and other socio-demographic factors also can play a role in this complex health issue, as discussed elsewhere on this web-site. (See the sections on Obesity in the U.S. and Relationship Between Poverty and Obesity.)

Many of these and other contributing factors affect everyone at some point during their lives, at least to some extent, but those who are food insecure or low-income face additional challenges and risks.