Runaway prices at U.S. fast-food joints and restaurants have made people skittish down the income ladder and executives at chains including McDonald's and Wendy’s recently said they worry about losing business from those on the tightest budgets. Roughly a quarter of low-income consumers, defined as those making less than $50,000 a year, said they were eating less fast food and about half said they were making fewer trips to fast-casual and full-service dining establishments, according to polling in February by Revenue Management Solutions, a consulting firm. The rising price of food is contributing to budget-conscious diners cutting back.