Watchdog Stiftung Warentest compared the meals offered by McDonald's, Burger King and German chain Kochlöffel, none of whose burger, chips and drink options did terribly well, the Süddeutsche Zeitung reported on Friday.
The overall winner was McDonalds with a "satisfactory" 2.9 on a sliding scale from 1 at the top to 5 at worst. Burger King was also ranked "satisfactory" with a 3.1 while Kochlöffel was just behind with 3.2.
Burger King's Whopper burger tasted better, the testers said, and this was at least in part because the meat was grilled over an open flame. But this also created problems, as the process created carcinogenic chemicals, they said.
All the menu meals came under fire for containing too many calories, too much salt and too much fat. Those with the least calories and fat were the McDonald's offering - but this was only because the portions were the smallest, the testers said.
They recommended that if eating at any of the fast-food chains, people order salad rather than chips with their burgers, and drink water or fruit juice rather than soft drinks.
Stiftung Warentest also researched how the big American chains treated their workers and the environment. It concluded that while McDonald's insists its franchise operators pay staff a union-agreed wage, this is only the case in around 80 percent of Burger King fast-food joints.
Even so, the watchdog said, the average day of most people working at either company were made up of over-time, under-staffing and an hourly rate which worked out at around €7.
All three chains used too much packaging, Stiftung Warentest said, while the palm oil used by Burger King and Kochlöffel probably came from huge plantations for which rainforests had been cut down. There are some sources of sustainable palm oil, the watchdog said, but this was not used by Burger King.