No I totally get that, makes a lot of sense to me. Populations that derive from fertile, stable climates with a history of large scale agriculture have far less incidence of obesity. Whereas hunter gather populations don't seem to deal well with the introduction of grains, dairy and alcohol.
Although I think in the future they might have more sophisticated methods than blood type, perhaps something based on haplogroups or something?
Myself I have to avoid grains and sugar otherwise I become consumed with thoughts of food.
I didn't like red meat as a child. I would spit hamburgers out in a napkin, and since I was raised in an old-school working class family, this was an outrage to my grandparents. Then again, I also didn't care for peas, and I absolutely love them now, so IDK.
Any food related problems I've had are due to compulsive behaviors, like emotional or stress eating, rather than eating any particular food.
On the other hand, I feel tremendously better when I stay away from junk food, and from what I understand, eating certain foods (pizza, ice cream, donuts, cookies, etc.) can actually chemically CAUSE compulsive over-eating because they don't send "full" signals to the brain due to lack of fiber plus the combination of fats and simple sugars triggers the starvation "store up for the winter" response in the brain, which worked for us in times where people suffered famine or less food in winter time, but works against us now in a time of plenty.
So I think it's best for all people to avoid eating a lot of sweets, processed white bread, and to only eat foods like pizza and cheeseburgers once a week or less, as a treat or once and a while thing, lest they be chemically inclined to ...keep eating. And if you keep eating high sugar, high fat items, it helps you to pack on weight.
I've tried doing low-carb and it made me feel terrible. However, trying to be completely vegan also makes me have weird PHYSICAL symptoms, like the last time I went vegan for a week, after 7 or 8 days my food was processing through my gut so fast it was bright green, which is indicative apparently of bile, and foods going through the system too quickly without proper nutrient absorption. Nice. Even after three or four days of vegan after a yoga retreat, I had this persistent "empty" feeling, like some vital nutrient was missing in my body. I can do vegan for a day or two, like to cleanse, but three days is probably max I can do vegan in a row.
I think low-carb is absolutely DISGUSTING. When people say they've been doing low-carb for years, I'm frequently surprised they aren't insane, clinically depressed, or suffering from kidney failure, heart disease, or intestinal blockages. Then I'm only left to presume that they're actually eating GOOD CARBS (whole grains) and not completely low-carb.
If some people really are healthier on low-carb, then they are definitely physically built differently than me, and the people who suffer things like heart disease from high protein, low-carb diets.
From all my research, apparently the healthiest people in world consume diets with lots of whole grains, veggies, fruit, olive oil or soy, some fish or limited lean meats, lots of beans and pulses, and many of their meals are vegetarian though they do eat meat or fish a few times a week, no more than once per day. The Mediterranean and Japanese diets are the healthiest in the world, as far as I can tell. Neither of them are low carb.
Vegetarian women also tend to weigh less than their meat-eating counterparts and have less health problems, like heart disease and breast cancer.
I'm completely convinced that many of the world's diets were formed out of necessity because of what was available, and may have even worked better for people in times when there was less food available part of the year to kind of balance out the consumption of fatty high-protein foods.
Still, I've also gathered that all people, in general, ate less meat before 1900, even in countries, like many in Europe not in the Mediterranean, consume a lot of sausage and red meat, but they didn't eat it all day long in huge portions. Even the French with their fatty, creamy, meaty diet actually only eat that way about once per day and the rest of the day eat a lot of whole grains, yogurt, fresh vegetables, and smaller portions in general, and don't consume processed snack foods.
If high protein, low carb diets work for some people, good for them, but I definitely don't think it's good for all people, and it's definitely not good for people's finances if they're on a strict food budget, nor is it very sustainable for the environment, unless a lot of your protein comes from things like nuts, cheese, and beans.