The effects of trying to lose weight.

So far I've lost 15 lbs. I just cut out cream, butter, bread, and sugar. I limit my carb intake. No cookies, candy, pop, cake... sometimes i lose control and inhale a donut but then i compensate with carrots and celery for the rest of the day. Skim milk, yogurt, and Beans are ok. Drinking water with lemon. But what has it got me? Gall stones for one. Having gall bladder removed on Wednesday. The other thing so far is bradycardia. My heart beat has gone from 60 to 48 beats a minute to conserve energy. Might also explain why i feel so lethargic. Combatting that by redoing the basement. Took a vitamin and have been taking potassium in several forms to prevent leg cramps. What else do i need to watch out for?