only by the type and amount of food that you are eating. start a food diary and keep track of what you eat and then look up these values on the internet. check on how many calories you are taking in each day...
Is there any way of checking the amount of protein and carbs present in the body??
At 18 with a BMI of 13 you are undernourished ... electrolytes and vitamins are not nutrients...you need protein and carbs otherwise you are not going to heal your ulcer and there will be continued muscle damage.
My levels of nutrients like electrolytes calcium and vitamins are in normal range. My vit d got low so i got it treated. So if there are no nutritional deficiency then is heart disease still a factor
Nutrition is a very important component for good health, and an improper diet can cause CAD and heart problems in the long term. You may want to consult with your doctor to bring your physical conditioning to an acceptable level with a diet and exercise protocol. I don't know the significance of the ulcer for your low BMI, but that may need an intervention as well.
Thanks for sharing,
Ken