Nora Gedgaudas in this AHS video
makes the point that plenty of animal sourced fats and proteins in your diet signal to your body that "hunting is good". This is the condition in which the cost benefit analysis of keeping extra fat tissue tips toward it being an impediment rather than a survival tool as it would be if your body is getting the signal through a low fat WW diet that there is a famine going on.
Taking that and running with it just a bit further, I have this working hypothesis. So some background info.
Plant matter in significant quantities is a "Plan B" food, something to keep you from starving when the hunt does not go well.
In this TED talk Dr Christina Warinner does a poor job of "debunking" paleo strawmen but there were some interesting points in her talk nonetheless.
Watch "Debunking the paleo diet: Christina Warinner at TEDxOU" Video at TEDxTalks
She points out how Paleolithic vegetables and fruits would have had little resemblance to the benign and nutritious stuff we have created and engineered which now fills the produce department. She cited the anti nutrients, fibrousness, and spiky defenses we have bred out of them and the sugar content we have bred in. No self respecting Grok would have bothered to collect wild broccoli or wild lettuce unless s/he was starving. It would just not have been worth the energy expenditure to do so unless the tribe was seriously hungry and had no other alternatives.
So, hypothesis: If you feed your body a lot of veggies, you are giving it the chemical signals that hunting sucks and it had better hold on to every available calorie for dear life. If you feed your body meat and fat on a regular basis, it gets the idea that hunting is great and it can relax and run the metabolism a bit higher even, catch some more of that yummy meat.
What do you think?