A new report says the government's program that gives families aid to pay for groceries is failing in some aspects of its execution, such as not accounting for many barriers to finding affordable, nutritious food by inner-city shoppers.

The report, which was put together by an independent group for the National Academy of Sciences, found that the program, officially called the Supplemental Nutrition Assistance Program, or SNAP, also lags behind the increasing cost of food and penalizes beneficiaries with jobs.

The U.S. Agriculture Department, which administers the aid program, commissioned the report to help it determine the best way to assess whether food stamps benefits are allowing families to have a healthy diet.

"We will thoroughly review the analysis and recommendations contained in this report and use them to help set our agenda for future program research," USDA said in a statement.

One aspect of the program the report says is inadequate is the government's response to rising food prices. The researchers found a 16-month lag between when the government assesses the cost of food and when it adjusts benefit amounts to accommodate price hikes.

"Because of the impact of inflation and other factors on food prices, this lag in the benefit adjustment can significantly reduce the purchasing power of SNAP allotments," the report said.

Panelists also found many instances where the program could better equip participants to eat a healthier diet. Food stamps are intended for buying cheap basic ingredients and unprocessed foods, and the dearth of affordable supermarkets in many cities means that urban dwellers, who represent a high proportion of those in poverty, must pay more for healthy foods, according to the panelists.

During the recession, demand for food stamps soared, with middle-class families who found themselves suddenly homeless and jobless pushing enrollment to a record 47.7 million people by September 2012. Even during the recovery, demand has remained high and food pantries and soup kitchens continue to feel the strain.

The program rankles many, especially some Republicans, who see it as a bloated government handout. Fraud concerns are also an ongoing issue.