It is basically avoidance of sugar and most carbs. It is being preached not only by Dr. Shen but by others including my GI, who did his Fellowship at Cleveland Clinic under Dr. Shen and is an avowed disciple of Shenian theory.
The theory behind this diet is that sugar and carbs serve to fuel the bacterial overgrowth situation underlying many cases of pouchitis. Antibiotics, probiotics and prebiotics are all methods by which one can combat this situation; elimination of foods that contribute to the situation is yet another means to fight it.
There is another thread on this topic and this is not a new revolution, it is one that started around 5 years ago. The bacterial component of pouchitis has become better understood and the dietary role in that has also become better understood.
What is interesting is that all of this is really a semi-logical extension of the theory that the higher incidence of IBD in the westernized countries is due to the growth of processed carbs and sugarized foods as dietary staples in those countries. If you speak to any registered dietician about how your body breaks down carbs and sugars that will also help you understand the theory. One dietician used the fire analogy as to how these foods burn in your body. Sugar is like paper and Carbs are like dry kindling wood - they burn instantly and rapidly. Protein and fats are like heavier logs that take longer to burn. Your body needs to be trained to eat these foods and it needs to be trained properly because you do need complex carbs which is your best source of carbs. Think chick peas and hummus and legumes for complex carbs.
Talk to a registered dietician and your doctor so you can construct a diet tailored to your needs and health situation. My diet has been approved and run by my PCP, my GI and 2 registered dieticians. My PCP however is an avowed practitioner of the theory that your blood labs determine the appropriateness of your diet, and nothing else. Since my blood labs are excellent, my diet is excellent, per his logic. I have no reason to dispute this logic. I have been on a modified Paleo Diet for almost a year and things have improved, noticeably.