Author(s): Laura Casu 1,*, Stuart Gillespie 2, Nicholas Nisbett 1
Malnutrition, in all its forms, is the largest single risk factor for the global burden of disease . Every country is affected, and many countries are dealing with a "double burden" characterized by the coexistence of undernutrition with overweight, obesity or diet-related non-communicable diseases (NCDs) . Alongside pervasive problems of undernutrition, the prevalence of overweight/obesity is rising dramatically, with 39% adults overweight or obese in 2016 . Obesity is increasing in most countries, in both urban and rural settings, and across socio-economic levels-raising the risk of NCDs such as type 2 diabetes, hypertension, dyslipidemia, and various cancers . 41 million of the world's 57 million deaths (71%) in 2016 were due to NCDs, with the highest burden falling on low and middle-income countries [4,5]. No country has yet succeeded in reversing this trend.
This paper responds to recent calls to review efforts to create enabling environments for 'double-duty actions' (DDAs) . In their potential for preventing or reducing several forms of malnutrition simultaneously by targeting common or shared drivers of both undernutrition and overweight , double-duty actions hold great promise, especially in populations where multiple forms co-exist. The acknowledgement of involuntary exposure to underlying and structural determinants informs the wide range of strategies to promote wellbeing in multiple settings and across the lifespan. As a necessary step in developing an integrated agenda for addressing the root causes of malnutrition at all stages of the life course, this review focuses on integrated interventions/initiatives that combine both nutrition and physical activity, which have yet to be reviewed through a double-duty lens. This will expand on previous research on single component actions, with the anticipation that such integrated initiatives are likely to be framed mainly as obesity prevention and control programmes. Yet, being implemented primarily in countries with a high dual-burden or in specific settings (such as locations with poor socio-economic indicators and vulnerabilities) with higher risks of multiple forms of malnutrition and food insecurity, they have high potential for addressing all forms of malnutrition and related comorbidities.
Undernutrition and overweight/obesity are systemically connected to broader socio-political determinants of disease [7,8] and act synergistically (or 'syndemically')  where they cluster in poorer and more marginalised populations. Such synergistic effects are important. The UN's 2018 State of Food Security and Nutrition in the World report  employed a conceptual framework (page 30) that highlighted different pathways from inadequate food access to multiple forms of malnutrition. In addition to food and nutrition insecurity, the key non-nutritional pathway to overweight and obesity is mediated by poor mental health. This is based on growing evidence of associations between food insecurity and anxiety, stress and depression that are independent of other indicators of low socio-economic status in both resource-rich and resource-poor settings [11-13]. Stress brought on by food insecurity may cause non-homeostatic eating and may lead to the selection of 'comfort' foods, or highly palatable foods that are rich in fat, sugar, and sodium [14,15]. Finally, physical...