Some athletes can adapt to performing in ketosis after a long time (years), but the more general trend is that a mix of VLC diet and exercise destroys people’s metabolism. Many end up putting on weight with hypothyroid symptoms. Your muscles need glycogen for workouts and without carbs, your body has to break down protein and fats to make glucose. Some people, especially those with liver trouble, have a limited capacity to do this and end up with a glucose deficiency. This can cause mucus deficiency, which can lead to constipation and dry eyes. Extracellular immunity also requires glucose. The glucose conversion process (GNG) also involves stress hormones, so anxiety and sleep irregularities are other common symptoms.
Working out can be good for improving health, but if you’ve busted your metabolism, you’ll need to stop until you resolve that. Otherwise keeping glycogen stores topped up will avoid the burnout you’re experiencing, as well as any potential for the symptoms I mentioned. It is a good idea to eat after a workout, but protein is another option. It’s not surprising you get flare ups with carbs, because avoiding them creates insulin resistance and ruins your glucose handling. Your blood sugar probably sky rockets, especially if you don’t blunt the GI with fat, which will make candida happy. It’s a good idea to get a good amount of rest to begin with though.