This study is definitely leading up to an FDA (they hope) approved, marketable diet. The actual study does give some hints at what the diet is comprised of,
"to last 5 days every month and to provide between 34% and
54% of the normal caloric intake with a composition of at least
9%–10% proteins, 34%–47% carbohydrates, and 44%–56%
fat".
... but reading further one finds this section:
"Human Diet
The human fasting mimicking diet (FMD) program is a plant-based diet
program designed to attain fasting-like effects while providing micronutrient
nourishment (vitamins, minerals, etc.) and minimize the burden of fasting. It
comprises proprietary vegetable-based soups, energy bars, energy drinks,
chip snacks, chamomile flower tea, and a vegetable supplement formula tablet
(Table S4). The human FMD diet consists of a 5 day regimen: day 1 of the diet
supplies 1,090 kcal (10% protein, 56% fat, 34% carbohydrate), days 2–5 are
identical in formulation and provide 725 kcal (9% protein, 44% fat, 4