I never saw it, but how was the premise a lie?
The main problem is that he used it as an excuse to over eat, and also stopped exercising. And then declared the changes in his health were on McDonalds. Some chick did a “counter” to it, she also ate McD every meal, but kept her calorie count healthy, kept up her exercise routine, and lost weight.
If you go to any restaurant and say “yes” to every “add on” you’re gonna gain weight. That’s just the math of excess. It’s not the restaurant.