She is a classic example of a modern-day paradox: as reliable access to healthy food declines, the likelihood of being overweight goes up.
The working poor like Caballero often have no time for cooking, little money to buy fresh vegetables, and a long walk to the closest supermarket with a good produce section.
"We have been pretending that it is easy to replace a diet of soft drinks and fast food with home-cooked meals, fresh fruits and vegetables," said Adam Drewnowski, a University of Washington epidemiology professor who has studied the problem.
The problem is pronounced in what seems an unlikely place — California's Central Valley, where much of the nation's produce is grown. The valley also has some of the highest poverty rates.
Although being overweight is usually associated with eating too much rather than with hunger, a growing body of research is showing that the people who have gained the most weight in the last decade tend to have the lowest incomes, and often go without the kind of food or the amount they need.
Caballero's neighborhood mini-market in the isolated farming town of Cutler offers a full array of processed foods in colorful packages — and battered apples selling for 50 cents.
"Many people can't afford to eat the produce they pick," said Drewnowski, who also heads a center for public nutrition. "These people are obese, frankly, because they have no money, and some diets are cheaper than others.
"The message has been to blame people — 'you're not choosing well, you're not educated enough.' We forget there are people whose choices are severely limited by finances and time allocation."
Caballero understands those limits and their consequences. During harvest season, she picks the grapes and oranges in the groves that surround this small town of Cutler. Fruit is available, and money is too. The family eats relatively well.
During winter, jobs are scarce, so Caballero feeds her husband and three children the cheapest food she can get: potatoes, bread, tortillas.
For Caballero, who has been diabetic since she was 19, the sugar-and fat-laden offerings of her local market are more than unhealthy: they're dangerous. Obesity is a leading risk factor for diabetes, an incurable condition in which the body can't break down sugars in the blood.
Cutler Elementary, which Caballero's children attend, has so many diabetic kids that teachers recently had an emergency workshop on how to handle blood sugar highs and lows. This in a school where 100 percent of the kids qualify for free school lunches.
After a 15-year-old diabetic student became blind — one of the consequences of untreated diabetes — the school sought help. Now, Caballero and other farmworker mothers attend a free nutrition class that considers their culinary traditions, low budgets and lack of time.
The women come because they know that the cheapest, fastest, most filling meal — the burger and soda that look so good at the end of a long day in the fields — is not the healthiest for their families.
In the class, one of at least 10 groups Dolores Vallejo teaches each week, the Spanish-speaking mothers learn to read English-language labels. Vallejo points out that "high fructose corn syrup," "sucrose" and "dextrose" all mean azucar — sugar. She shows them several quick, inexpensive, low-fat recipes their families might enjoy, like vegetable chili.
Unfortunately, most public health programs don't address such issues. As processed foods rich in sugar and fat have become cheaper than fruits and vegetables, the poor in particular are paying a high price with obesity rates shooting up, followed by diabetes.
This is happening even as conditions associated with malnutrition — like anemia, caused by an iron deficiency in diets lacking leafy greens- continue to plague poor children, said Jay Battacharya, a health economics expert at Stanford University's medical school.
Walking out of the nutrition class, Caballero and the other mothers said they appreciate the tips on healthy eating. But they still have to scrape to pay extra for real fruit juice instead of the punch they now know is mostly sugar and water. And they still have to walk four miles, often with their children, to and from the nearest supermarket, where fresh produce is plentiful and less expensive.
Along the state highway linking Cutler to the supermarket in Orosi, a new sidewalk has just been laid — a testament to the women's efforts to feed their families better.
"I want to feed my family better food," said Irene Flores, a farmworker with three children who stores large sacks of beans to eat during the winter. "My husband was asking me to buy lettuce, because he likes salads. How can I buy it at almost $2 a head?"