Yeah, as mentioned by other this is BS. I have been living on a diet consisting of less than 30grams of net carbs/day for over 3 years and my primary food is from meat, chicken, and fish. The only carbs (sugar of any variety) that I eat are from berries (strawberries, blackberries raspberries, etc) and pecans walnuts and almonds.
In fact I went from 2200 kcals to 3400kcals and in that time, I am lost 65lbs (first 6 months) and have kept it off; my total cholesterol has decreased from 150 to115, my HDL is up and my LDL is down. My blood pressure when from 130/75 to 110/65. My memory has improved and I have WAY more energy.
The body IS much better off using ketones for energy.