3 direct anagrams of the word DIET: Tied, Tide and Edit.
Tied = binding to complicated methods.
Tide = endless cycles of rebounds & regrets.
Edit = changes after changes from various failed fad diets.

The only direct anagram for the word FAST: Fats
To deal with Fats, the most direct, flexible and permanent way is Fasting.

If Pain is Weakness leaving the body,
Hunger (temporary till ketosis kicks in) is Fatness leaving the body.

This, my friend, is the true 'FatSecret'.