I have had 2 Impossible burgers. I am not in love with it, but as a diabetic with high cholesterol, it made it taste better, lol. Low carbs and ZERO cholesterol. Yes, the bun and toppings add carbs.
In a 2018 patent, it looks like they may get healthier with their coming Version 3.
From the patent summary>>>
"In some embodiments, the iron complex such as a heme-cofactor, e.g., a heme-protein, and the one or more flavor precursor flavor additive compositions can be soy-free, wheat-free, yeast-free, MSG-free, and free of protein hydrolysis products, and can taste meaty, highly savory, and without off odors or flavors"