For some time now, and from year to year more and more, it is happening that many dietary protocols that are the prerogative of bodybuilders or athletes become commonplace, perhaps among people who do not know what a barbell is or who do not particularly like activity. physics: and so, people write to me asking me if they are doing well to follow De Pasquale’s metabolic diet , talking to me about loading and unloading carbohydrates when in general they do not even know how to count the daily macronutrients, with the result that they simply mess ; or people who ask me if in my opinion (I who then not being a nutritionist or dietician but simply a blogger cannot give professional advice) injecting hormones can make them lose weight.
How they have heard or seen it done and so on.
That is: are you serious?

Here, it is appropriate to make a distinction. And this distinction must also be made in the case of the so-called 80/20 diet.
That’s not a diet. But a food strategy often adopted by those who make a flexible diet or IIFYM: generally a sportsman.
We distinguish the dietary cycling of athletes and some more or less drastic nutritional or dietary practices from strategies that can work even for us mere mortals. 
Copying some eating patterns like a duck without having discussed with a doctor and without knowing how those eating patterns were born in general is not an aid to weight loss. Buying a thermogenic or other substance because some athletes take it in the definition phase will not magically change our sedentary metabolism.

The 80/20 strategy itself says nothing, if you don’t look at the context. Simply, it is a strategy whereby during the day we eat for eighty percent of our needs in a clean way (the sense of this clean is very vast, we will see later) and for twenty percent of our needs in a dirty way, for example by allowing us a small cheat. This method, illustrated by Alan Aragon , has also been developed over the years by dieticians and nutritionists, as I explain here . The goal is to make the diet sustainable every day, and basically to eat healthy, without then finding yourself with nervous hunger, forbidden dreams starring the parmigiana or a huge cupcake in tails,
However, the problems are not to be underestimated and we must know them to correctly apply this strategy which in fact can be effective both if we are on a low-calorie diet.