Oct. 14, 2011 -- When entering the vast 2.2 million acre expanse of the Pine Ridge Indian Reservation, it's hard to miss the picturesque surroundings of windswept plains and sharply eroded foothills. But go deeper and prairieland too arid for farming and poverty that rivals that of the third world becomes apparent.
There is not a single mall, nor a movie theater, a big business, nor a bank on the South Dakota reservation. But in downtown Pine Ridge, a Subway restaurant franchise is busy all day long.
"We focused on Subway mainly because of the opportunity it offered in healthy eating," said owner Bob Ecoffey, who opened his business in 2008.
An area the size of Delaware and Rhode Island combined, the reservation is considered a "food desert," defined by the U.S. Department of Agriculture as a low-income community without ready access to healthy and affordable food. Ecoffey, who is also the Bureau of Indian Affairs superintendent for the Pine Ridge Agency, tells ABC News that healthy foods like fresh fruits and vegetables are unavailable because of what he says are limited resources.
"The opportunity just doesn't exist for many people across the reservation," he said.
Ecoffey said Subway offers that opportunity.
Tashina Banks, a member of the Cheyenne River Sioux tribe, is the hiring manager at the Pine Ridge Subway. She shared with ABC News the story of an elder woman from the community who was moved to tears during the store's grand opening week.
"She came in here and literally was crying because of what having this kind of a store or food restaurant in the community meant," Banks said. "Not only because you see people investing in our own community, but also because, she said, 'I haven't eaten a cucumber in years because they're so expensive.'"
There's only one large supermarket and typically the price of staple items across the reservation are more expensive because of its remote location.
There is an epidemic of obesity on the reservation, and it's contributing to a startling statistic: The reservation has a the lowest life expectancy in the nation. Men, on average, live to be 58 years old while women's average life expectancy is 66 -- in both cases almost 20 years less than for the rest of the country.
Ecoffey and Banks want to change that. One of their first employees lost more than 125 pounds within a year of being hired.
"She was our Jared," Banks said, referring to Subway spokesman Jared Fogle, who lost more than 200 pounds, thanks in part to limiting much of his diet to Subway meals.
The reservation's "Jared" is Melarie Iron Moccasin. Moccasin, 30, grew up on the reservation, has a family history of diabetes, and says she had been overweight her whole life. "When I started working here, I weighed my heaviest at 356 pounds. ... Now I weigh 177 pounds. So altogether I lost 178 pounds."
Losing half of her body weight was life-changing for Iron Moccasin, who noticed a drop in her sugar levels and a spike in her activity. "Outside Subway, I tried my hardest to not go out and eat. I'd rather buy my own food and cook at home. That way I can control how much fat and sugar I eat."
Banks said that when it comes to healthy eating, education is the key.
"The reason that people eat so poorly is because a lot of times it's convenient, it's cheap, and it's what they have always known," she said.
At Pine Ridge, 60 percent of all households receive public assistance, meaning they have an income less than $2,000 a month for a family of four. Each month, eligible households can pick up government-issued commodity boxes, known simply as "commods," to maintain a nutritionally balanced diet.
Some say the "commods" miss the mark, offering only canned meats, cheese, with limited options for fruits and vegetables, and a lot of starchy carbohydrates. Food stamps are preferred by most. Families on the Pine Ridge Indian Reservation are at least six times more likely to be on food stamps than those across the U.S. Residents can drive as much as an hour away to stretch their funds at the handful of supermarkets near the reservation.
An alternative to faraway stores is Pinky's, a convenience store and small Laundromat in the Pine Ridge community of Manderson.
"We are here to ... meet the needs of a community that is far from major shopping areas," said Pinky Iron Plume Clifford, who has run the store for the past 28 years. It is a one-stop shop for top sellers like sodas, as well emergency food items including frozen dinners, milk and eggs.
"If you run out, you have to go to town. There's nothing worse than having a customer come in to buy eggs and you don't have any. Or an item that they need, baby formula, and we don't have it. So you drive the 45 miles to get it," she said.
Clifford recently added fresh fruit and vegetables to her inventory but said the store loses money on the produce, which is pricey to transport.
At Ecoffey's Subway, fresh vegetables are trucked in weekly from Billings, Mont. -- more than 400 miles away. Ecoffey has opened another Subway franchise in nearby Martin, also on the reservation, which receives its fresh supply of produce from Omaha, Neb., 500 miles away.
Despite the high cost of transporting the produce, the restaurants turn a profit thanks in part to the constant business they get from Pine Ridge residents. His customers, Ecoffey said, are getting a good deal.
"For a five-dollar meal," he said, "you can get a whole variety of vegetables that simply people can't afford in a grocery store."
Watch a "20/20" special, "A Hidden America: Children of the Plains" with Diane Sawyer tonight at 10 p.m. ET.