Food costs money, so people who are poor have less money to buy food.

Therefore, people who are poor are less likely to be overweight or obese right?

Makes sense, but the conclusion is wrong. In survey after survey, rates of obesity turn out to be highest among people with the lowest incomes. The numbers are greater for women than for men, but for both genders.

Americans living near or below the poverty level have much higher rates of obesity than affluent Americans. And despite their obesity, these lowest-income Americans are also malnourished. How can this be so?

In 1995, a pediatrician named William Dietz, now considered a leading expert on obesity, published an account of a 7-year-old patient: a girl weighing more than twice her ideal body weight and living in poverty.

Dietz entitled his case study “Does Hunger Cause Obesity?” and proposed two possible scenarios in which it might: When a family lacks money, its members choose foods that provide them with the greatest number of calories at the lowest cost. These foods tend to be high in fat and sugar and low in nutrients, such as vitamins, minerals, and fiber.

Thus, although overfed, individuals on this kind of diet can be significantly malnourished.

When a person experiences hunger, the body adapts by slowing energy expenditure and “hoarding” calories:In other words, episodes of food shortages might cause increased body fat.

More recently, Angie Tagtow, head of the Hunger and Environmental Nutrition group, identified another possible link among hunger, malnutrition, and obesity: the family’s living environment.

Economics influences not only what a family can afford to buy but also where it can afford to live, and this affects its proximity to quality food stores and farmers’ markets versus fast-food restaurants and convenience stores.

Economics also affects access to transportation, social services, and nutrition education and assistance. Adam Drewnowski, director of the Center for Public Health Nutrition of the University of Washington, adds one more factor: the greater palatability of low-cost foods. In other words, chips and cookies tend to satisfy our taste buds more than peppers and pears.

He cites laboratory studies suggesting that we’re more likely to overeat cheap junk foods, and contends that limited money for food may shift a poor family’s purchases toward more palatable foods that fill people up with the maximum calories at the minimum cost.

Drewnowski points out that a low-income family of four gets $104 a week in food assistance, which breaks down to $3.71 per person per day.

Think about it: If you had just $3.71 to buy a day’s worth of food, how would you spend it? Would you be more concerned with getting the right balance of nutrients or purchasing high-volume, less nutritious foods that keep hunger at bay throughout the day?