The best thing about this is that people can try it out for themselves; try eating a carnivore diet, basically beef, butter, bacon and eggs, for 90 days. Then, if you're feeling brave, try eating refined grains, cereals, skim milk, etc for another 90 and let your body tell you what it feels best on.

If you want to check your glucose spikes, you can also purchase a continuous glucose monitor and see which meals spike it the most (spoiler, it's not the fatty meat).