I do think people can easily get confused between the two, I am type 2 and have started doing allot of exercise. I was warned off at the gym with bloods being low because they didn’t understand the difference.
Your bloods rise a bit when you exercise hard - thats your body giving you the energy you need and is a good thing. With me, they come down pretty quickly and if they are down in a few hours i wouldn't worry about it (Think of it like eating a meal but you’re eating your internal sorts of energy). There is a limit to how much energy your body can convert quickly which is why the below applies.
I’m not going to talk in terms of "hypos" because that is something to do with diebetics on medication and has already been covered. I will however talk about normal function during exercise while on that diet.
If you don’t have enough fuel in your body, because you have not taken enough calories this can cause issues for other reasons not really to do with diabetes. It depends on your intensity of exercise; you can get away with low to medium intensity exercise on a low amount of calories.
If you take 220, minus your age and about 30 - 50% of that is low to moderate exercise (if you measure your heat rate).
70% + of that number is high intensity.
So for me, 220 – 34 = 186 bpm. 70% of this is 130bmp – so if my heart gets that high its considered higher intensity exercise.
In simple terms, if I train hard in the high intensity zone, without eating before I dont perform as well, feel weak towards the end and can also get a bit nauseous. This is normal and is caused by a lack of fuel – for me I lose less weight on low calorie because I need the fuel to exercise which gives and overall better weight loss for me.
I can however do plenty of moderate exercise without fuel – just keeping my heart rate in the lower range at <100bpm.
Your not going to “hypo” org et very ill, but if you don’t take on enough calories and do allot of exercise you will more far more likely to tire easy, perhaps feel sick. I now eat something before I train because I need the energy as my intensity is increasing as my fitness increases.
If your keen on the exercise and will keep it up, I would go for a lower calorie but not crazy low calorie diet until you loose the weight. My aim was to lose to healthy weight range normally, then hit something like the 800 calorie diet if I cant drop my bloods. As it happens losing 4 stone has (at least for now) fixed my bloods given my current varied and not specially low carb diet. This was aided by intensive exercise.
You don’t need to monitor your heart rate, that’s a new one for me to be honest recently - but its more to point out that if you plan to work out hard, you will find it very difficult on a low cal diet, if you work moderately - you may well find you can cope. You will not however "hypo" you will just totally suck at what ever your doing and maybe feel sick if you don’t have enough energy - that’s normal and totally different from a drug endused lack of glucose.