I would dispute that we need carbs for fuel. The body can switch over to burning ketones if necessary. And the body can make glucose from protein. It is possible to live for long periods of time with very little carb in the diet. The traditional Eskimo diet, for example, is low on plants - for obvious reasons. Eskimos were actually healthier when they were eating their traditional diet.

I suspect that just eliminating obvious sources of sugar would help some people with unstable moods. Unfortunately so much of what we eat is processed crap that has added sugars, you'd still be getting a lot of sugar even after eliminating cookies, candy, ice cream, etc. Nevertheless, it's a good place to start. Sweets are necessary, and they play havoc with your blood sugar.

More and more I'm just cooking real food. It requires more effort, but I know what I'm putting in my mouth. Last night I made stuffed peppers. I used grass-fed beef (which is higher in omega-3's), green bell peppers, olive oil, tomato paste, some spices, and a little rice. Except for the rice and the tomato paste, none of it was 'processed' or 'manufactured' (why do we have food manufacturers! )