Is it ok to take a blood test after eating?

Blood tests & eating: Only a few blood tests require that you be fasting--most particularly tests for sugar (glucose) and a lipid panel (because the triglycerides go very high after eating. Most other tests do not require a fasting state--including electrolytes, thyroid tests, liver tests, total cholesterol & HDL cholesterol, kidney function, and blood counts.

Depends on type: Many tests require you to be fasting (blood glucose for one), but there are many others that do not. If you do draw blood of eating all of the fatty molecules and triglycerides form a layer that can precipitate out other substances that need to be evaluated.