Three-month notices were mailed last week to about 132,000 residents who receive the food aid.
The letters warned able-bodied residents with no dependents that they must be working or enrolled in job training at least 20 hours a week by February or lose their benefits.
Hawaii Foodbank Inc. sees big problems ahead, with the bad economy and unemployment already lengthening hunger lines.
The nonprofit organization works with 300 agencies that distribute food to the needy. Those agencies have seen food lines grow 10 percent to 30 percent.
"This is just the beginning," said Bleu Blakslee, development director for Hawaii Foodbank. "We want to make the public aware we are in a time of great need."
Hawaii Foodbank said the food stamp reforms come at a time when jobs are difficult to find.
"The provision threatens to remove the only form of public assistance for many needy persons who are willing to work but unable to find jobs," Hawaii Foodbank said in a statement.
"An estimated 5,000 unemployed adults in Hawaii may lose food stamp benefits in an average month under the new welfare law, according to the Center on Budget and Policy Priorities. ... Approximately 40 percent of these jobless are women; nearly one in three are middle-aged persons over age 40."
The food-stamp revisions can be waived in areas of high unemployment, the foodbank said, adding that Hawaii is one of those areas.
Although reforms passed by Congress in August mean welfare rolls and checks will be cut significantly by February, so far the phones at the Department of Human Services aren't ringing off the hook with worried callers.
Officials don't know what to make of that and perhaps won't until the checks stop coming.
"We don't know if they're not interested or they don't know about it," said Henry Ku, department spokesman. "We can't make too much out of it yet."
Ku said the government doesn't know how many people will be affected as cases are being reviewed, but the pool of candidates is large. As of September, 131,898 in the state received food stamps.
Some cuts don't depend on jobs. All checks for general welfare and Aid to Families with Dependent Children will be 20 percent less starting in February.
The reforms also tighten eligibility for the 10,280 legal immigrants receiving food benefits.
Unless they are active duty military or veterans, or they have worked for at least 10 years in the United States, they won't be eligible.
The new law increases penalties for food stamp fraud as well.
To offset some of the cuts, the state has loosened other requirements such as how much assets you can own to still be eligible for welfare.
"We're cutting benefits on one hand and letting them keep more money of the other," Ku said. "It's not just cut, cut, cut. We want to encourage them to work."
The reforms are complicated and confuse government officials, let alone welfare recipients, especially those who do not speak English as a native language.
Letters of notice are sent only in English.
Translators are provided upon request but sometimes immigrants are too shy to ask for them.
Ku said officials are meeting with groups of 20 or more who call his department for information.
They have also met with nonprofit groups that serve immigrants.