Jon is correct, it is simply a mathematical equation for weight gain or loss, and watch heart rate as stated. However, keep in mind calories are the fuel to burn that relates to skeletal muscle energy and can be stored for future use, but the heart uses and needs blood/oxygen (does not store oxygen) on a real time basis for an energetic and normal output. The faster the heart beats more oxygen for fuel increases and can be a vicious cycle...calories do not matter, but an abnormal heart rate can be an indication the heart is not meeting the demands and the heart is being overworked.
You state the symptom is angina...did your mother have a test that indicates there is a lack of good blood flow to certain areas of your heart? Often chest pain is not angina! Angina would be chest pain, etc. that is related to the heart not receiving an ample supply of oxygenated blood. Your mother's doctor can help determine if the chest pain is angina by providing a nitro med. The nitro will or should dilate the coronary vessels providing a better flow of blood to the heart muscles and relief from angina. Also, often angina develops as a result of exertion, and there is relief with rest..
The information provided on this forum should be considered a guide, insight and a perspective on the issues of interest to better provide introspection for productive communication on the health matter with your health professional. Generally acknowledged, your mother should get involved with aerobic exercise that can help maintain a healthy heart and a healthy diet to maintain proper weight.
Thanks for your question, and if you have any further questions or comments you are welcome respond. Hope your mother and you have good health going forward in the New Year. Take care
For the most part, weight gain is simple mathematics, you take in m ore calories than you burn and the excess is stored in fat cells. Your mother can do some sort of exercise to burn calories, she just needs to watch her heart rate and work load. Just moving burns calories so a simple walk will do it. If walking is too much, some time moving in a pool is very helpful.
In any case, she needs to cut back on her calories to match what she burns in a day. Just being awake burns calories, but if she is gaining weight she needs to find a way to take in less or burn more, its that simple.
She needs to talk to her doctor about what is safe for her.
Good luck,
Jon