The US is notorious for its weight problem. With just 5% of the world’s population, it’s home to 13% of the world’s overweight and obese people. Roughly two-thirds of adults in the US are overweight or obese and, even more alarming, 38% of boys and girls aged 10 to 14 years.

At first glance, these numbers seem to reflect over-abundance — Americans have more food than is good for them. But the problem is more complicated than that, and worse: many of the same people who struggle with extra weight also regularly go to bed hungry. That may sound like an impossible contradiction, but dig deeper, and it quickly becomes clear how hunger and obesity are related. Both are often rooted in poverty.

Food insecure adults in the US are 32% more likely than others to be obese — especially if they are women

Nearly 12% of American households are, by US agriculture department standards, “food insecure” — meaning they have difficulty buying enough safe and nutritious food to meet their household needs. This amounts to roughly 40-million people, including some 540,000 children who experience very low food security.

Food insecurity tends to be highest among Hispanic and black non-Hispanic families, and, of course, among unemployed and poor households.

Food insecure adults in the US are 32% more likely than others to be obese — especially if they are women, one study found. Another revealed that children living in food insecure households have a greater-than-average tendency to be overweight or obese, and have poor eating habits.

Other studies suggest that food insecure children also tend to display significant behavioural problems, disrupted social interactions, poor cognitive development, and marginal school performance. These challenges, in turn, increase their risk of becoming obese adults.

Poverty and unemployment have driven the dual rise in food insecurity and obesity since the 1960s, especially in rural America. But many city dwellers subsisting with inadequate social services and support structures are also susceptible.

Food-insecure and low-income families face unique challenges that impair their ability to consume a healthful diet and maintain an ideal body weight. Their lifestyles tend to be sedentary because of their built environments, and their food tends to be served in large portions.

The relatively inexpensive, calorie-dense food at their immediate disposal often lacks the nutrients needed for optimal health. As a result, though they may follow a nutritious diet for short periods, these are punctuated by cycles of financial and personal stress that lead to food deprivation, overeating, limited access to health care, reduced opportunities for physical activity and greater exposure to unhealthy food environments.

From Congress to food banks

How can such cycles be minimised? It will take a concerted effort from many actors. The US Congress, for one, should increase funding for the supplemental nutrition assistance programme — food stamps — on which 50-million American families depend. And it should shift agriculture subsidies away from their heavy focus on corn, soybeans and other Big Ag crops and towards the farming of fruits, vegetables, nuts and legumes.

Local food banks, an important resource for food insecure households, deserve the support of citizens and communities, and should be encouraged to provide more fresh foods and fewer processed foods high in salt, sugar and unhealthy fats.

Employers can help, too, by providing mental and physical wellness programmes, as well as discounts and subsidies for physical activity programmes. These investments are inherently worthwhile, because employees who exercise tend to have better concentration and work output.

Finally, hospitals and health clinics can help working households provide healthy meals by creating what are called prescription food programmes: hospitals provide a set amount of money for each patient household, or a prescription that can be redeemed for nutrient-rich foods, including fruits and vegetables, in participating nearby markets or grocery stores.

The goal for governments, healthcare providers and community groups should not be limited to building more markets in neighbourhoods that now lack for healthy groceries. It’s also essential to encourage more community gardens and farmers markets; subsidise healthy foods; promote nutritious food choices; and ban junk food advertisements to children. Fighting against obesity and hunger is a matter of fighting for basic food security — even here in the US.

• Fanzo is a Bloomberg distinguished professor of global food and agricultural policy and ethics at the Nitze School of Advanced International Studies, the Berman Institute of Bioethics and the department of international health of the Bloomberg School of Public Health at Johns Hopkins University. This column does not necessarily reflect the opinion of the editorial board or Bloomberg LP and its owners.