Here’s my high level summary:
Carbs are a cheap solution for getting someone out of total starvation mode, but so is alcohol. So I’d argue, they are not meant for living and thriving.
Alcohol is a fuel source and can be used calorically. I’m not calling it nutritious. It is easily transported. A bottle of wine has about 600 calories. Very few spoil-free foods can pack 600 calories into that relatively compact format. Consider how much space it would take to carry the wheat you’d need to make 600 calories or indeed the grapes. So alcohol is a solution for starvation mode. But that makes it very temporary.
Carbs are also to be a temporary solution for starvation or pre-winter planning. Your body can hold – in it’s accessible forms – about a day’s worth of carbohydrate/glucose calories. They are best for getting someone out of starvation mode. But they won’t improve you. So if you are unhealthy now, you need to get healthy first. If you are healthy, you don’t need carbs but they probably won’t hurt you.
If you get hangry, you are on the carb cycle. Fuel with carbs; crave more carbs. Break the cycle by focusing on fat and you’ll stop getting hangry.
A bit more:
Alcohol – no storage in the body. You will use this up first. The body cannot store alcohol as fuel. So it will use any ingested alcohol before it uses your glucose, fats, etc. It is a legit fuel source. It is not a nutritious fuel source. There’s no body or brain benefit to consuming alcohol. That said, there’s clearly a social benefit for many of us so use your powers wisely.
Carbs – this includes veggies, yeah, I said it – limited storage in the body. You can hold about a day’s caloric requirements in the body. Some of these have possible health benefits, many do not. Choose your carbs wisely. Let’s stop selling ourselves that there’s much nutrition benefit. You’ll know you’re consuming too many carbs if you crave them. It’s a dastardly cycle. You eat carbs, your body craves more – why? It wants you to pack on fat for winter. If you over consume carbs (especially fruits because #fructose), the excess gets shoved into fat cells and becomes harder to reach immediately but is ready for you when starvation aka winter hits.
Fats – this seems to be the money maker with respect to body fuel. Your body – a lean body – holds about a month’s worth of calories in fat. If you’re overweight you have even more stored potential. It’s possible for any healthy adult to fast for about a month. I’m not recommending that, but know you won’t starve if you decide to make the switch to keto or keto-like diet. The bugs in your gut may yell at you, but you’re not starving it’s just noise. Within a few days those gut bugs will be replaced by different gut bugs who will be far more amenable.
Proteins – mixed bag here. In the presence of carbs protein will act like a carb with respect to digestion. Yes you have X equivalent calories stored as muscle, but your body does not want to use protein or muscle as fuel. It’s the last thing that gets pulled apart. So eat your protein and stay active. But don’t sweat using protein as fuel.