I googled for it but found way too much information and I couldn't wade through those long words. So please keep it simple.
I've been in a 1,200 calorie diet for about 10 days. Quite simple: lean meat, veggies, legumes, fruits and some milk in very small portions. No problems here, I've done this before and it always worked.
Last Wednesday I exercised for nearly 2 hours (water workout + underwater spinning) and about half an hour later I felt dizzy and nauseated. But I forgot about it later. Then on Friday the same thing happened, only this time I got drenched in sweat and was very close to passing out completely. I was in juice shop and looked around to see if there was any hot strong guy to support me if I fell, so that I could sigh and look all delicate and helpless, but there wasn't any, so you see how frustrating the whole experience was.Kidding aside, it's just an overall unpleasant experience and I'm not used to this.
I'm not in any medication and I'm not diabetic or have any heart condition. I had those checked last year when my father had heart problems. That's why it's so problematic to find good info, google just wants to convince me I have to have those to nearly faint after exercise.Oh, and my blood pressure has always been in the normal range.
I gather there is something missing in my diet? Basically, how can I do cardio for two hours without fainting like a Victorian virgin later?
I hope this doesn't come across the wrong way.
As a fairly serious recreational cyclist (I'm currently riding about 120 miles a week and my body fat is somewhere around 10%), and I've done a considerable amount of research about nutrition and exercise.
So, feel free to take or ignore my advice as you see fit.
I think the right approach is to adopt a reasonable eating plan - something like South Beach is a good choice - and eat when you are hungry. Your goal should not to diet, it should be to come up with a plan that works long term.
But... diets like south beach are not designed for people who exercise a lot. I've run into a lot of people who have tried the approach that you are taking, but *none* of the cyclists I know take that approach. They fuel up with carbs to support their exercise.
The reasons are simple. During exercise, you burn both fat and carbohydrate, but the amount of time you can exercise is mostly dependent on how much carbohydrate you have stored. If you take in carbohydrate while you exercise, you can exercise longer. If you take in carbs immediately after, you restore the carb stores, and suppresss your appetite.
I'd suggest reading "food for fitness", by chris carmichael, and south beach if you haven't already.
Kidding aside, it's just an overall unpleasant experience and I'm not used to this.