Under the lithium theory, the amount of lithium in water/food accumulates as water sources go downhill, thus explaining the altitude connection, so just an altitude connection is strictly less “cuckoo”.
From the obesity map and my experiences living across the country, I would be surprised if regional cuisine/habits ends up mattering more than altitude, but might be worth testing more rigorously.
Under the lithium theory, the amount of lithium in water/food accumulates as water sources go downhill, thus explaining the altitude connection, so just an altitude connection is strictly less “cuckoo”.
From the obesity map and my experiences living across the country, I would be surprised if regional cuisine/habits ends up mattering more than altitude, but might be worth testing more rigorously.