Women struggling to put food on the table are more likely to be overweight than those with a reliably full refrigerator, according to new research1.

From a US government survey of food intake of almost 10,000 Americans nationwide Marilyn Townsend of the University of California, Davis and her colleagues find that the prevalence of obesity increases among women as their household income nears the poverty line.

More than half of the women who reported not having enough to eat were overweight, compared to 34% of food-secure women. This study - the first to examine the relationship between hunger and obesity with such a large number of people - challenges the stereotype that people are overweight only because they're too well-fed.

The paradoxical idea that food shortages could cause weight gain was first proposed in the mid-1990s, but so far, only one other study of 193 rural women in New York state has suggested a possible link2.

Townsend's study did not look at other factors that may affect obesity such as eating patterns or family medical history, so it's still too early to point to poverty conclusively as the primary cause of obesity.

Nonetheless Moira Tidball, a nutritionist at the Capital Area Food Bank in Washington DC, feels that the link between hunger and obesity is a real problem, especially when an estimated 12% of US households have an uncertain food supply. "It's a malnutrition of a different sort," she says. People are stretching their dollar to buy the wrong kinds of food.

Poor neighbourhoods often lack large grocery stores, forcing people, especially those without cars, to shop at small, local convenient stores which stock little fresh fruit or vegetables but plenty of high-fat, high-starch processed food, says Tidball.

Those short on time and money often resort to cheap fast food and sugar-laden drinks. And many lack the knowledge to recognize the value, for example, of fruit juice over fruit-flavoured sugar drinks. Indeed, the study found higher levels of obesity among poorly educated women.

Non-profit organizations are trying to meet this need for nutrition education with national programmes in major US cities teaching healthy cooking and eating.

Townsend's group suggests another reason why obesity strikes the poor: lack of control over their food supply. Americans relying on government food programmes receive food vouchers once a month. If they run out in the last week of one month, they may over-eat rich foods at the beginning of the next. Binge eating over time can lead to obesity.

Women as managers of the household food supply often deprive themselves to feed the rest of the family, leaving them more vulnerable to the famine-feast cycle of eating, says Christine Olson, a Cornell University researcher. She has documented this behaviour through interviews with food-insecure women.

With obesity and other diet-related diseases such as diabetes on the rise, "we need more research that documents the health consequences of food insecurity," says Olson. Hopefully politicians will realize the high health care costs and be motivated to better address the hunger problem, she adds.

If further research confirms the link between food insecurity and obesity, Townsend and co-workers suggest that government food aid programmes may need revising.