Diet and exercise tells people what to do, but not how to do it.

Knowing that you should do something, doesn't necessarily mean can do it. There's still the question of exactly how.

E.g., diet is heavily influenced by hormones/hormonal cycles and access to quality food choices, which vary significantly between people. The glp1s available now are a big help with the hormonal part of this, but they are not within reach of a large proportion of people.

> To me this is just subconscious denial/defending of their food addiction.

If you have to make up unobservable phenomena to explain plainly visible facts, it's usually a sign to look for a different overall model.