If you are 5' 8 and weigh 236 pounds how many calories should you consume to lose weight?

It depends. The younger and more active you are, the higher your metabolism. Personally, I'm sixteen and a runner, so I burn off all the food I eat. With your weight, I'd say you burn at least 3.5 thousand calories a day - that's equal to a pound of fat. So if you really were desparate, fasting would drop about a pound a day. Just remember to drink water. G'luck.