However people aren't zero carving. People just reducing it to a sensible level.
They also aren't saying all fat is healthy and at any quantity.
However high carb, and sugar in particular foes spike insulin which causes a crash, which is what a lot of us struggle with and why a lower carb approach works.
If you have a "lower carb approach" then you are basically always in the depressed state. If you really are having big crashes after eating carbs then you should see your doctor and get tested for diabetes, that isn't normal in a healthy adult.
When you wake up in the morning after 8-10 hours of fasting that tired, hungry grouchy, lazy body is simply missing blood glucose. Best way to perk yourself up is to absolutely eat carbs. Getting tired and struggling to finish your workout at the gym, that's you running low on sugars- make sure you eat plenty of carbs the day (replace glycogen storage) and hours (raise blood glucose) before a good workout.
Carbs and especially sugars are digested quickly which is exactly why they are so useful in your diet, combined with fats and proteins will prevent any kind of "crash" or felling of hunger until the next meal time.
If you demonize any one kind of food you are really missing out on the big picture.
The biggest causal factors of type 2 diabetes is being overweight and under exercised (which of course are correlated). Exercising for 30-60 minutes a day massively reduced Diabetes risk, as well as risk form all kind of other diseases from strokes to heart disease and cancer. Worrying that fruit has a lot of sugar in it and" therefore is bad" is about the last thing you should be worrying about.
I'm not saying there aren't benefits to watching the carbs you eat but it is pointless demonizing them and looking for a quick fix by blaming the food industry for adding sugar. If I am forced to be more sedentary then I will drop my carb intake a little - but that is by no means a healthy alternative to exercise. If I am trying to loose weight then I also loose carbs because it is easier to reduce calories by reduces starches than meat, but I will also reduce fat simply because it is so calorific. And at no chem will I reduce fruit and vegetable consumption over the fears of carbs.
Also, instead of low carbs if you are really worried about insulin spikes then you need to follow a low glycemic index diet,, many carbs actually have a relatively low GI and a digestive time comparable to proteins and fasts, and many fruits have a similar GI to vegetables despite the "OMG so many sugars!!!!"
