> > Also, there is no calorie reduction
> Sure there is, that's why you lost so much weight.
It's important to appreciate there's more nuance than simply calories eaten vs. calories expended.
Some calories are more bioavailable than others. The OP described eliminating refined carbs and sugars, and adding substantial sources of dietary fiber. The effect of this is switching from quickly absorbed (and likely stored) calories to slower to digest, less available sources.
It's entirely possible for sugars locked up in a web of dietary fiber (i.e. fruit) to pass through the small colon and be consumed by bacteria in the large colon producing flatulence, or pass through entirely. If that same sugar was consumed in more accessible form, as with a cup of coffee, it would entirely be available to the person at a fast rate, accompanied by an insulin response making the energy likely to be stored as fat.
Understanding this is key to appreciating how one could even increase their oral caloric consumption and still be losing weight, all else the same. Just because it goes down the hatch doesn't mean 100% of those calories reach the bloodstream. What you eat matters a great deal, both in terms of availability and hormonal response.