There's a very large difference between making sure you get the appropriate level of mono unsaturated fats that you would find in things like avocados and fresh fish, versus what Dahl is obviously referencing which is the concept of obesity.

You will not locate a doctor on this entire planet who would agree that obesity is healthy, it places far more load on the joints, and puts additional stress on your organs.

Either you have a deeply profound misunderstanding of the adjective fat versus the noun fat, or you're deliberately misconstruing the authors intent to fabricate an argument for why censorship is OK.