That compares with about 10 percent of consumer budgets in developed countries, and as much as 50 percent in the poorest developing countries, Baffes said.
Part of the reason Americans spend less of their discretionary income on food is because U.S. consumers are wealthier than consumers in many other countries, giving us more money overall to spend. That means Americans can devote less of their total budget to a greater variety of foods, such as fish, meat, dairy and processed foods, while people in less developed countries are putting more of their money into basic foods, like wheat and rice.
Read MoreThe rising cost of a trip to the supermarket
But that's not the whole story, especially when it comes to how much we spend compared to other wealthy nations.
Experts say one big factor is food production. Food has become a global industry, but Clauson said Americans still produce a fair amount of the grains, fruits, vegetables and meats that we consume, and we do so in a relatively efficient and cost-effective way. That saves us from having to pay extra to have that food shipped from elsewhere.