Lightheaded & Excersise
 

I have a history of blacking out. It comes pretty randomly and all docs I've talked to have been unhelpful. Last time I went biking which was after starting the diet I passed out pretty hardcore. I thought I'd hurl. I'm paranoid if I try to workout on this very low cal diet I'd pass out and may not wake up. Or something.

I hope you find out what is wrong. If your Dr has approved you working out then my advice is as follows:

I wouldn't advise working out hardcore on a low calorie diet. For example if you are eating 1200 calories I wouldn't think you would do 700 calorie burning workout (not in your condition) I have done this and I am perfectly healthy. And it left me weak sometimes!! Maybe you should increase the amount of calories you eat and do low impact workouts (several if you need a certain calorie burn). Walk Away the Pounds, Pilates, Yoga until you find out what is up.

This is a medical issue, above all else, I do suggest calling your Dr (the office/nurse) and asking for their recommendation on your calories and workout. Best of luck!

You mentioned a "very low cal diet" but did not say how many calories you are eating. Sounds like you definitely need to be under a doctor's supervision with your dieting. I do that even though I am basically healthy and do not diet but just do a healthful eating and exercise plan (but I do not do "very low cal" because I don't think it is good for my health).

That's very serious matter. If the doctors could not explain it you must not do anything before you can find an expert opinion about it. Take good care. Thank you.

I'm assuming you've had your blood work done if you've talked to a doctor about this...? I had this issue and found out it was my iron levels, maybe try taking an iron supplement or perhaps just a really good multi-vitamin and see if that makes a difference... It could also be dehydration, are you drinking enough water?

Definitely get blood works done. I have a habit of fainting too, thanks to low iron and blood sugar so I have to be very careful. I would also think about how many calories you're taking in. Maybe it's better to lose the weight a bit slower, than risk an injury from blacking out?

I know I am bumping a zombie thread here...but if you experience lightheadedness/blackouts during or after exercise...or any time really....don't stop with just blood work. And don't just assume it is lower than normal calories. It might not be iron, blood sugar, thyroid, ect. Get an EKG. It might be your heart. And a lot of doctors aren't going to just do a random EKG on something like this unless, especially if the only symptom is passing it. I recently have found I have to learn a lot, more than I care to admit, in regards to this. Something I never thought I would have to think about. Blood work came back normal, all tests have shown to have no reason to cause my dizzy/blackout spells. Doctors were stumped. I had a pulmonologist try to get a more concrete answer and sent me for an EKG. That's how they discovered I have a genetic disorder. Still in the process of getting it all figured out, it is less than a week old diagnosis. But none the less, get EVERYTHING checked out. That's my two cents.

I had the exact same problem for years. Over time, the events have become less often, but they do occasionally occur from time to time (once every couple of months). Sometimes I get faint when I'm doing nothing but standing around. When I went to the doctors about this issue (about 5 years ago), they ran all sorts of tests and nothing showed up. I had bloodwork done (to test for anemia, thyroid problems, diabetes, etc.), an ultrasound of my heart, x-rays of my chest, and I wore a heart monitor for 3 days. Everything came back normal and the doctors had no answers for me, so I just ignored it.

Hopefully you'll have better luck with the problem and the doctors can actually diagnose you.

I agree with zoesmom on the EKG referral. You should get one ASAP. I was born with a heart problem that is confusing in and of itself but when I started experiencing dizzy spells and fainting spells accompanied with nausea, I immediately went to my cardiologist. After many tests, they determined it wasn't heart related and referred me to a neurologist. No results there either, even after an MRI. So I just dealt with it. When I went to work out and I felt like I was gonna faint, I would stop, sit down, wait it out and then get back to my workout. I wasn't going to let it stop me (though it did make me DREAD going to the gym). It wasn't until the beginning of 2012 when my cardiologist, having heard my symptoms of dizziness and fainting went and scored over the echocardiogram I had taken and found that I had an ASD (atrial septal defect) that was out regular view for years. He determined it was too big not to take action on and gave me a month to get my school assignments in order to have an ASD repair. They found out it was FIVE TIMES the size he originally thought which accounted for my horrible dizziness and propensity to faint a lot. The night after surgery, I was up and practically buzzing around my hospital room. I had so much energy (oxygen) to my brain that hadn't been there in years and years. And to this day (2 years later), I haven't once felt dizzy or fainty while working out. This may not be your situation, but ASDs are pretty common.
In any case GOOD LUCK and BE CAREFUL about your workouts because this is a serious thing and you should not take it lightly. At all.