Probably everyone has friends who go low-carb and credit it with at least short-term weight loss and feeling better. I never know what carb means, but I usually assume pastries, donuts, etc. Seems obvious it would improve health to reduce them.
There was a big study in the Lancet published a couple weeks ago and I've had time to ponder it and hear its critics. Food versus health studies are so emotional...
I've come to believe it's an extremely credible study with a few unmistakable conclusions:
1. If you seek to replace carbs with animal-based sources of protein and fat, then the average reduction of lifespan is 4 years.
2. If you are very high carb, you are probably taking in a lot of refined carbs like soda, and it too is associated with reduced lifespan, but not as much.
3. If you replace carbs with plant-based sources of protein and fat, the loss of life expectancy can be much lower but it depends on the source. Lentils, nuts, veggies seem fine.