Bullshit.
East 5,000 calories a day of prime rib and lobster ONLY and you will gain weight if you don’t burn it off.
The reason zero carb diets work is because they suppress appetite.
You probably can’t eat that much. But if you did you would not store fat. I have been eating all the meat I want for 7 years. I lost 40 pounds. I eat what I want. I rarely exercise. And I can’t gain weight. I eat, eggs, cheese, nuts, green veggies, and lots of meat. I never touch corn, wheat or sugar in any form. Wife did the same. She lost more.
Your body is not a perfect calorie burning engine. It burns alcohol first, carbs second. And lastly it goes after fat. If those are not there it will go after protein, preferring to use the protein for muscle maintenance.
By the way we have had several complete cardio tests. We pass with flying colors. We have no arterial plaque. Our blood work is super. And we feel great. Better than before.
Some people can stay thin while eating carbs. Many can’t. If you are type 2 or boarder-line diabetic, you can’t.