Does anyone know whether this diet induces a grotty mood, perhaps because of just 'being hungry' or any other reason? DP has been on it for 3 weeks now, but seems to have morphed from a generally relaxed and generous person into a slightly aggressive/cutting/unpleasant man, which frankly is making me feel anxious and wanting to be well away from his company right now. It's happening a bit to other people, but more in my direction right now. I'm interested to know if anyone else has experienced this, whether I just need to encourage him to stop or whether it goes away once your body is used to it.
He shouldn't be hungry. If he's hungry 3 weeks in, he's not eating enough fat - unless he has cheated a few times his body should be used to not getting carbs by now (I think you can feel 'hungry' in the first few days but it's a craving for carbs).
One possibility that just struck me - I was re-reading Volek and Phinney last night and they suggest that people who low-carb-high-fat and eat mainly soybean/peanut/sunflower oils etc feel crap. Whereas those who eat animal fats, olive oil, coconut oil feel much better. What fats is he eating?
It takes some people longer to fat-adapt so the spell where they are sort of 'under-fuelled' is longer. The blood glucose is lowering but the body is a little more reluctant to use the ketones instead. Hopefully it will pass fairly soon. Maybe try more fat and possibly a few nuts between meals. The other possibility is something more on the lines of Paleo where they don't drop the carbs quite so low. That seems to suit blokes. Because they carry more muscle their sugar needs can be a bit different.