[timbit42]

It would taste like crap and no one would eat it.

[darawk]

You could use artificial sweeteners. Also, there's plenty of lean meats or plant-based diets that are low in fat and sugar while remaining reasonably palatable.

[grondilu]

Where is the energy supposed to come from if there is neither fat nor sugar?

[proteinman]

Protein. And there are carbonhydrates besider sugar...

[smartbit]

Try a proper Vegan meal and you’ll be astonished how good a low fat meal would taste without sugar. The app Happy Cow can help you find a nearby Vegan restaurant.