The human being diet.
2 days vegetables, herbs and spices, water only...
Then 14 days without oil, sugar or carbs (that means no rice, pasta, potatoes, pastry, bread, processed food (as it tends to have starches and oil) though sweet potatoes, eggs, cheese, meats are ok in reasonable proportion). Eat three times a day with zero snacking, and a five hour fast between meals.
After the two weeks, you can introduce olive oil, and one feast meal per week when you eat anything you want. Continue until you reach your target weight.
There's lots more detail, but that's the essence.
I've done it before and it worked well - lost over 10lbs in first three weeks and felt so much better.