Rich pickings for the slender

It can be a hard idea to get your head around in downtown Melbourne or Sydney but malnutrition and obesity can, and frequently do, coexist: in one person, in one family and can even cascade through generations.

We are not talking about far-flung countries, some other war-torn, famine-stricken, headline-grabbing place. Even in impoverished Australian societies we can see the effects on the community of the combination of poor education, limited resources, and distance from fresh food sources. Obesity is one of the most serious health problems we face, and we welcome discussion of its effects on our poorest communities.

Reports in The Weekend Australian of obesity hysteria, especially an exaggeration of the problem of childhood obesity - except within lower income families - is consistent with our research that shows the problem is greatest in disadvantaged groups.

The greatest risk factor for poor health and the complications of obesity - cardiovascular disease, kidney disease and diabetes - exists in people from disadvantaged backgrounds.

Research has shown us that traditional diets from many cultures have inherent protective qualities. Problems in health are most likely to occur when communities move away from these traditional diets. This is as true in Australia's Aboriginal community as it is in the nation's Greek, Italian, Arabic and African communities.

Traditional diets evolved over centuries and meal preparation was always closely aligned with food freshness, seasonal availability, and lifestyle. Today, there is a great gulf between the move towards "convenience" foods and calorie expenditure; food affordability and nutrition.

In short, the poorer you are, the less bang you get for your food buck. Food choice is not just personal, it's political.

Plot a graph of kilojoules-a-gram v kilojoules-a-dollar, and we find an inverse relationship. All the foods we are telling people not to eat (foods rich in fats and refined carbohydrates), those are in fact the best value for money when you're hungry and feeding a family on few dollars. All the foods that we are encouraging: fruit, vegetables, lean meat and fish are very expensive. And the further you move away from the city centre, the more expensive they are.

Those living in poverty frequently go hungry and this drives unhealthy eating patterns. Eating large amounts of whatever is available is a natural response to prolonged periods of insufficient food and in terms of health it is the worst possible way to eat. When money is tight, parents will sacrifice for their children. And in times when there is plenty of food around, those parents will often then - even more than other people - eat as much as they can. It is possibly the worst way to eat if you are to avoid gaining weight. Add to that the fact that the types of foods chosen are frequently the worst choices, because they are the cheapest.

And so we see serious weight problems, most prevalent, as research reported at the weekend confirms, in disadvantaged groups. We have to shake off the notion that obesity is a sign of affluence: increasingly, it is a sign of poverty, and one of the most powerful symbols of Western privilege is a slim and toned adult physique.

Over-nutrition and under-nutrition can exist in the same household - put bluntly, fat adults and skinny kids, or fat adults and fat kids - but it is all a sign of malnutrition. Skinny kids in fat households often means that the child still has a faster working metabolism and has not yet learned to overcompensate when food is available.

We know that some people are spending up to half of their income on food. In many instances, that is not money spent on a good diet. We have calculated that if these people spent another 20 per cent of their income - which they can't do, that would be 70 per cent - they could afford a healthier, more reasonable diet.