Hi, First, even if you work out regularly, please respect the natural metabolism of your body. A light meal or no meal at all is advisable before any aerobic or anaerobic exercise. In fact, exercise itself increases your energy levels and preempts hunger quite effectively. Allow your body to settle after a meal before undertaking any sort of vigorous activity. This could take anywhere from half an hour to one hour and depends on your age and baseline activity levels, too. Dizziness, shaking and sweating can occur from a vasovagal syncope which means there is a sudden shock to your system from hypoglycemia/hunger/unusual activity. If this is a one off incident, you can forget about it, but if it becomes a pattern then you need to consider all these points. The possibility of a viral labyrinthitis or vestibular neuronitis may be kept in mind. These two are completely harmless and self limiting but could cause all the symptoms you have described. The tiredness and weakness might be due to a low grade infection/inflammation (and in current context even Covid, but no, you DON T need to rush for a test; just be careful of and for others around you) and also the effect for severe retching/vomiting. Second, you might be having a degree of reflex acidity (for various reasons other than diet- such as an ulcer, stress, food allergy, preservatives and chemicals in the food, or a problem such as hiatus hernia) so any intake of food or even the lack of it could trigger a wave of nausea and/or vomiting/giddiness/shaking/sweating. In such a case, you need to get thoroughly evaluated by either ENT or Gastroenterology. Third, adequate intake of water is advisable to maintain good metabolism. Plus avoidance of smoking and alcohol, except in moderation. Also, excessive amounts of tea/coffee may also increase reflux so ensure that this is not the case. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Jayita Poduval, ENT Specialist