Thank you for the question @marko37
Every body responds differently to (Queal) meals, but feeling tired should of course not be the response.
Although our products are made so that they release energy throughout the day, it could for instance be that it might be a bit much to process. Could it be that you've maybe replaced a smaller meal with a full Steady shake?
Could you try and drink the meal over a longer period of time?
If you haven't had any other problems with feeling tired after eating a meal, then I don't expect any problems with insulin regulation in your body (but please do consult with your physician if you're feeling sluggish after other meals too).