McDonald’s advertised the chicken fajita as containing 2.5 grams of saturated fat but, on at least one occasion, the fast-chain chain served up the dish with 4.32 grams — about 75 per cent more than the amount of bad fat it claimed.

At one KFC location, the chicken strips packed in a total fat count of 19.37 grams, not 12 as stated by the company.

And Taco Bell’s fresco soft taco was supposed to contain 0.2 grams of trans fat — a fatty acid that consumers try to avoid because it raises the blood levels of the so-called “bad” cholesterol. But a test found the level to be 3.5 times greater at one outlet, where a taco weighed in with 0.7 grams of trans fat.

Some food chains fail to meet own fat limits