If a single part of this blend of characteristics is not treated at its best, the athlete could still get a good performance, but he won't win.
The daily diet, i.e. how the athlete eats every day, must therefore be considered just like a workout.

Practical advice on what foods to eat and how to eat them
Take fat, carbohydrates and vegetables away: are we sure?
This is a major mistake, first of all because a reduced lunch leads to consume more carbohydrates than necessary to stimulate satiety, with the risk of accumulating more fat mass, then because allocating proteins only in the evening limits the daily intake, which will then make us absorb a smaller amount than necessary for muscle development.

As anticipated, it is not possible to provide a universal diet. It must be personalised. But in addition to the rules at the basis of a healthy diet - vary foods, prefer whole grains, limit red meat and cold cuts, never miss fruits and vegetables ... - The best advice you can receive is to follow a balanced diet favouring the foods of the Mediterranean territory.

For those who feel the need or are used to prepare both first and second course, a tip: reverse the order of the courses.
Sports endurance nutrition
Even today, and unfortunately even among nutrition specialists, this old idea still stands:
In an endurance competition, an athlete consumes a lot of energy, so he has to intake an identical amount.

However, by carefully choosing the foods we put in the dish, the frequency of their consumption and their quantity, you can enhance the effects of training, favouring for example the production of mitochondria (ie the power packs that each cell has) in the muscle, and especially by increasing the body's ability to oxidize lipids during performance. This is a fundamental factor in sport in general, and in endurance in particular, since it ensures greater autonomy and limits the risks of falling into an energy crisis.

Omega-3 polyphenols and fats

Among the fats, the important thing is to choose the good ones.
Regarding the latter, nowadays food technology offers us valid supports. Omega 3, the good fats present in fish and therefore in its oil, can be easily eaten in gelatine pills that contain purified fish oil - i.e. free of toxic substances the sea is rich of and that we would ingested by frequently consuming the fish - and concentrated, i.e. rich in EPA and DHA. In this way you don't have to take the nauseating spoonful of oil "that's good for you", as happened decades ago.
Cocoa

Good news and bitter news: The good part is that an athlete can always eat cocoa. The bitter part is that we only talk about small quantities of "black" chocolate, that is, more than 75% of cocoa. There is in fact a low concentration of flavanols (the polyphenols of cocoa) in chocolate tablets.
It is better to take cocoa powder high in flavanols.
Turmeric

Curcumin unfortunately has a low bioavailability, our body absorbs only 0.5%, and since turmeric is used as a spice, the useful amount that is taken at the table is really minimal.
Curcumin is excellent when combined with green tea catechins.