HAVANA — For Lisset Felipe, privation is a standard facet of Cuban life, a struggle shared by nearly all, whether they're enduring blackouts or hunting for toilet paper.

But this year has been different, in an even more fundamental way, she said. She has not bought a single onion this year, nor a green pepper, both staples of the Cuban diet. Garlic, she said, is a rarity, while avocado, a treat she enjoyed once in a while, is all but absent from her table.

"It's a disaster," said Felipe, 42, who sells air conditioners for the government. "We never lived luxuriously, but the comfort we once had doesn't exist anymore."

The changes in Cuba in recent years have often hinted at a new era of possibilities: a slowly opening economy, warming relations with the United States after decades of isolation, a flood of tourists meant to lift the fortunes of Cubans long marooned on the outskirts of modern prosperity.

But the record arrival of nearly 3.5 million visitors to Cuba last year has caused a surging demand for food, causing ripple effects that are upsetting the very promise of Fidel Castro's Cuba.

Tourists are quite literally eating Cuba's lunch. Thanks in part to the U.S. embargo, but also to poor planning by the island's government, goods that Cubans have long relied on are going to well-heeled tourists and the hundreds of private restaurants that cater to them, leading to soaring prices and empty shelves.

Without supplies to match the increased appetite, some foods have become so expensive that even basic staples are becoming unaffordable for regular Cubans.

"The private tourism industry is in direct competition for good supplies with the general population," said Richard Feinberg, a professor at the University of California, San Diego, and specialist on the Cuban economy. "There are a lot of unanticipated consequences and distortions."

There has long been a divide between Cubans and tourists, with beach resorts and Havana hotels effectively reserved for outsiders willing to shell out money for a more comfortable version of Cuba. But with the country pinning its hopes on tourism, welcoming a surge of new travelers to feed the anemic economy, a more basic inequality has emerged amid the nation's experiment with capitalism.

Rising prices for staples like onions and peppers, or for modest luxuries like pineapples and limes, have left many unable to afford them. Beer and soda can be hard to find, often snapped up in bulk by restaurants.

It is a startling evolution in Cuba, where a shared future has been a pillar of the revolution's promise. While the influx of new money from tourists and other visitors has been a boon for the island's growing private sector, most Cubans still work within the state-run economy and struggle to make ends meet.

President Raúl Castro has acknowledged the surge in agricultural prices and moved to cap them. In a speech in April, he said the government would look into the causes of the soaring costs and crack down on middlemen for price gouging, with limits on what people could charge for certain fruits and vegetables.

"We cannot sit with our hands crossed before the unscrupulous manner of middlemen who only think of earning more," he told party members, according to local news reports.

But the government price ceilings seem to have done little to provide good, affordable produce for Cubans. Instead, they have simply moved goods to the commercial market, where farmers and vendors can fetch higher prices, or to the black market.

Havana offers stark examples of this growing chasm.

At two state-run markets, where the government sets prices, the shelves this past week were monuments to starch — sweet potatoes, yucca, rice, beans and bananas, plus a few malformed watermelons with pallid flesh.

As for tomatoes, green peppers, onions, cucumbers, garlic or lettuce — to say nothing of avocados, pineapples or cilantro — there were only promises.

"Try back Saturday for tomatoes," one vendor offered. It was more of a question than a suggestion.

But at a nearby co-op market, where vendors have more freedom to set their prices, the fruits and vegetables missing from the state-run stalls were elegantly stacked in abundance. Rarities like grapes, celery, ginger and an array of spices competed for shoppers' attentions.

The market has become the playground of the private restaurants that have sprung up to serve visitors. They employ cadres of buyers to scour the city each day for fruits, vegetables and nonperishable goods, bearing budgets that overwhelm those of the average household.

"Almost all of our buyers are paladares," said one vendor, Ruben Martínez, using the Cuban name for private restaurants, which include about 1,700 establishments across the country. "They are the ones who can afford to pay more for the quality."

By Cuban standards, the prices were astronomic. Several Cuban residents said simply buying 1 pound of onions and 1 pound of tomatoes at the prices charged that day would consume 10 percent or so of a standard government salary of about $25 a month.

"I don't even bother going to those places," said Yainelys Rodriguez, 39, sitting in a park in Havana while her daughter climbed a slide. "We eat rice and beans and a boiled egg most days, maybe a little pork."

Rodriguez's family is on the lower end of the income ladder, so she supplements earnings with the odd cleaning job she can find. With that, she cares for her two children and an infirm mother.

Trying to buy tomatoes, she said, "is an insult."

Another mother, Leticia Alvarez Cañada, described what it was like to prepare decent meals for her family with prices so high. "We have to be magicians," she said.

The struggle is somewhat easier now that she is in the private sector and no longer working for the government, she said. She quit her job as a nurse to start a small business selling fried pork skin and other snacks from a cart. Now she earns about 10 times more every month.

"The prices have just gone crazy in the last few years," said Cañada, 41. "There's just no equilibrium between the prices and the salaries."

While many Cubans have long been hardened to the reality of going without, never more than during what they call the "Special Period" after the collapse of the Soviet Union, a new dynamic that has emerged in recent months threatens the nation's future, experts warn.

"The government has consistently failed to invest properly in the agriculture sector," said Juan Alejandro Triana, an economist at the University of Havana. "We don't just have to feed 11 million people anymore. We have to feed more than 14 million."

"In the next five years, if we don't do something about it, food will become a national security issue here," he added.

The government gives Cubans ration books to help provide staples like rice, beans and sugar, but they do not cover items like fresh produce. Tractors and trucks are limited and routinely break down, often causing the produce to spoil en route. Inefficiency, red tape and corruption at the local level also stymie productivity, while a lack of fertilizer reduces yield (though it keeps produce organic, by default).

Economists also argue that setting price ceilings can discourage farmers and sellers. If prices are set so low they cannot turn a profit, they argue, why bother working? Most will try to redirect their goods to the private or black market.

"From the point of view of the farmer, what would you do?" asked Feinberg, the California professor. "When the differentials are that great, it requires a really selfless or foolish person to play by the rules."

Paladares sometimes go directly to farms to buy goods, and even provide farmers seeds for specialty products that do not ordinarily grow in Cuba, like arugula, cherry tomatoes and zucchini.

Most acknowledge that they distort the market in some ways, and this year the government stopped issuing licenses for new restaurants in Havana. But some restaurant owners argue that it is the government's responsibility to create better supply.

"It's true, the prices keep going up and up," said Laura Fernandez, a manager at El Cocinero, a former peanut-oil factory converted into a high-priced restaurant. "But that's not just the fault of the private sector. There is generally a lot of chaos and disorder in the market."

On the outskirts of Havana, Miguel Salcines has cultivated a beautiful farm. Rows of tidy crops stretch toward the edge of his modest 25 acres, where he employs about 130 people.

Though he grows standard products on behalf of the government, there is no product he is more excited about than his new zucchini. A farmer for nearly 50 years, he had never grown the crop before, but planted a batch two months ago.

Now, the vegetables are coming into shape, the spots of bright orange flowers visible amid the green plumage. He knows this crop is not for the regular market, or for the government. It is like the arugula he grows.

It is for the tourist market and, by extension, the future.

"We are talking about an elite market," he said. "The Cuban markets are a market of necessity."