Changing A Positive Thought To What?

So when I do Thought Download every morning I notice that I have thoughts that repeat every single day that cause me to feel over desire to eat flour and sugar.

Now, Brooke teaches us that we should look into being curious about thoughts that make us feel negative feelings, however my desire inducing thoughts cause me to feel in the moment a pleasurable feeling.

To desire food and anticipate eating it soon, feels actually good.
I get a release of the dopamine ahead of time, I picture my favorite food, I visualize myself enjoying it, it all feels good.
It’s only later the result it creates for me that I don’t like (gaining weight).

So my brain seems confused about it (my prefrontal cortex) because it asks, ‘If the feeling I have is positive, why would I change the thought? And should I change it to a negative thought?’ If so, what negative thought I need to change it to so that I will not feel these good feelings caused by over desire?