Dangers of refeeding too quickly too soon:

Refeeding syndrome is a metabolic complication that occurs when nutritional support is given to severely malnourished patients (Box 2). Metabolism shifts from a catabolic to an anabolic state. Insulin is released on carbohydrate intake, triggering cellular uptake of potassium, phosphate, and magnesium.
This as per Medscape
Basically the body uses up too fast the available minerals, in case of overly zealous and inappropriate refeeding, and not only the body but also the blood even get depleted from minerals. Potentially one could die if the depletion is important.
It is important to introduce food slowly and to eat high mineral density food, which will be also high vitamin and nutrient dense vegetables and fruits.
Eating bread, pasta, tacos, fried stuff, the heavy dairy and meat and concentrated protein of any kind may make one loose the benefits acquired with so much effort.