But there was also scepticism about the plan to bring in "all-you-can-eat" fries, with one adding: "Something is wrong with America." The offer raises the prospect of customers hitting their daily calorie intake much more quickly.
A large order of McDonald's fries already contains 510 calories - or a quarter of an adult's recommended daily intake. The 24 grams of fat is also a third of an adult's daily allowance.
McDonald's has also begun phasing out its wraps at more than 14,000 US outlets as customers continue to opt for burgers instead.
The changes are being overseen by McDonald's chief executive Steve Easterbrook, who is British and took over a year ago with a mandate to shake up the firm.