when i was on a diet, i made my own recipe without using any flour or refined sugars.
instead of flour, try almond meal (crushed almonds) or crushed walnuts. They work just like flour and because it's made from nuts, it's not refined and therefore much healthier (you could also use wholemeal flour, except i'm not sure exactly how it would taste).
For your sugar component, which you're going to need since no sugar and you can't have a cake. I used a variety of berries, blueberry, strawberry etc to give the cake that "sweet" taste.
So you could make a cake and just switch ingredients...also make sure to avoid lots of butter, won't really need it, eggs are fine, maybe some pecans on top of the dessert would go good.
In the end, haven't used flour or sugar, the worst things in most desserts, but have made a cake with all natural ingredients. Obviously, still, don't binge on it, have a small slice or two, but a much healthier option overall and the taste, imo, is still quite good!