>This probably explains the obesity crisis too
>Meat is much more calorie dense compared to vegetable
>I wonder how much this accounts for obesity
From my experience, probably very little. I've been hard-core keto for almost 10 years now. I initially lost 100lbs and I've easily maintained a healthy weight ever since. The vast majority of my diet is meat and fat and I do not count calories.
I agree it would be quite hard to get obese from eating a diet rich in meat, because protein is very satiating and expensive to digest.
If you are obese, eating more protein (including meat) is a good idea, and doing a lot of strength training, to get your metabolism working.
It is very easy to become obese from eating bread, pasta, dairy, and sugar in processed foods, I have done that.