According to the gunas, what is the best type of diet and why?

Answer from the V.M. Samael Aun Weor and the magazine.

“Foods, Rituals, Charities, and Austerities are also threefold. Listen to me to understand their distinctions: Sattvics (that is, individuals in whom the Guna Sattva predominates) like foods that increase vitality, energy, strength, health, happiness, and appetite, and that are tasty, oily, substantial, and pleasant.” (vegetables, fruits of all kinds, etc.)

Samael Aun Weor.

Answer from the magazine "The The wisdom of the Being.".

SATTVIC FOODS

Individuals in whom the Guna Sattva predominates like foods that increase vitality, give them energy, strength, health, happiness, and appetite, and that are tasty, oily, substantial, and pleasant: vegetables, fruits of all kinds, etc.

The Magazine "The Wisdom of the Being" 108: "The Three Foods."