First things first. Ayurveda is one of the world's original medicine forms, dating back many thousands of years. It was the original and most concise form of food combining. Modern food combining is a relatively 'new' term (coined circa 1920s) by Dr Hay, then later on it was termed nutripathy by Dr Martin in the 1970s - today it is known more for the pH aspect via modern day luminaries such as Dr Robert Young and both Cayce and Jarvis.
So no, it is not a fad.
And you only have to try it for a short while for your body to be able to tell you that yes, it is the way our bodies prefer we eat.
Please follow up with my other pH articles and more on your stomach's plea.
Basically the food combining theory is founded upon the most optimal eating process for our digestion, assimilation and health - removing inflammation and in turn, disease. Interestingly, even though it is miles ahead of modern dietetics and standard diets, experts spend so much time slamming it you would think it was the diet responsible for obesity, heart disease and general poor health.
Some people base their dietary choices on still including meat and dairy or the original Ayurvedic advice if you prefer easy to follow tried and tested methods. But for simplicity, meals are planned around combinations of either protein and neutral or starch and neutral. Digestion and assimilation are optimal, weight loss or gain is easier, acidity is reduced, inflammation is reduced - ie poor health is reduced.
So how to make planning simple? I find the easiest way is to have a simple chart printed up on your fridge, which you can use for your shopping list also. While preparation methods, habits and recipes will have to be adjusted, once you 'get it' this way of eating is really easy.
Note: packaged and processed foods are not included for a reason.
And for the definitive list, I find the easier the better. If your preferred foods are not there, please ask if they are foods at all (ie processed) or if they are just compare them to the different plant foods and what is closest (ie different nuts or for example, various brassicas or similar plants).