DEAR DR. DONOHUE: I live with my niece. Now, at age 62, she weighs 297 pounds and is very swollen. She retains fluid. She has gone on many diets. None has helped. She takes off a little weight but then puts it back on, and she ends up weighing more. She cannot walk long distances. I pray you have some suggestion of what might help her. – A.P.

ANSWER: Even if your niece does retain fluid, the retained fluid doesn’t constitute most of her 297 pounds. She might lose some fluid if she closely watches her salt intake.

Most of her weight is fat, and fat is a true enemy of health, so she has to view her weight as an illness. I know other people like your niece who diet resolutely but can’t budge the scale downward. Weight gain is simplistically presented as an imbalance between the number of calories taken in and the number of calories burned off. A calorie deficit, therefore, ought to slim a person. In some people it doesn’t seem to, and I can’t explain why.

Your niece is at a stage when she would profit by considering weight-loss surgery. It’s an option not to be taken lightly. It’s reserved for the seriously overweight who cannot lose weight by dieting and exercise. Some of these surgical procedures can be done with a laparoscope – a viewing tube inserted into the abdomen through a small incision, along with instruments also inserted through a small incision. Recovery is relatively fast.

DEAR DR. DONOHUE: I hope you can help me. Both corners of my mouth are split and are quite sore. The doctor says it’s not a virus. What is it, and what can I do for it? – F.J.

ANSWER: It’s angular cheilitis (key-LITE-is). “Chelios” is the Greek word for “lip,” and “itis” tacked onto the end of a word indicates inflammation. “Angular” points to the corners of the lips. Saliva constantly bathing the lip corners softens them and eventually leads to painful cracks. Poorly fitting dentures, mouth breathing and constant lip-licking can cause an accumulation of saliva at the lip corners. So can age. With aging, the upper lip overhangs the lower lip and fosters pooling of saliva. In addition to saliva, the yeast Candida often takes up residence.

To cure the splits, you have to get rid of the yeast and calm the inflammation. A cream like Lotrimin AF or Micatin should be patted on the corners of the mouth and left in place for a couple of hours. Then the area is dried and a cortisone cream is applied. This procedure should be repeated at least twice a day and again before bedtime. Once the cracks heal, protect the lip corners by using ChapStick or something similar to keep saliva from collecting on that area.

You shouldn’t tackle this on your own. Get your doctor in on the act. The doctor can confirm this diagnosis and can prescribe a more powerful cortisone cream than the ones available on drugstore shelves.

DEAR DR. DONOHUE: I crave salt. I sprinkle it heavily on an egg in the morning. At noon I sprinkle it on potatoes, and in the evening on meat, corn or tomatoes. As a snack I eat raw potatoes sprinkled heavily with salt. My mother used lots of salt on her food. She lived to be 96. – B.

ANSWER: Most often, salt craving is a learned hankering. You were conditioned to grab the saltshaker by your mother, and she, probably, by her mother. You should conquer the salt habit. Even though it didn’t hurt your mother and apparently hasn’t hurt you, too much salt can raise blood pressure.

Slowly wean yourself off your high-salt diet. Cook and season with things like lemon juice, lime juice, vinegar, pepper and the large array of herbs and spices found in every grocery store. In a month or so, you’ll wonder how you tolerated so much salt on your food. You’ll experience tastes that salt had been completely obliterating.

DEAR DR. DONOHUE: Many years ago in Bolivia, I traveled a winding cliff road to the top of Mount Chacaltaya, whose high point is 18,274 feet. During my stay I had a constant dull headache. Now, many years later, I have a similar headache that reminds me of the Bolivian headaches, which were related to the drop in oxygen pressure. If I take six to 15 deep breaths, the headache goes. Does old age (87) bring on oxygen deprivation? – B.E.

ANSWER: The lungs of an 87-year-old aren’t the lungs of a teenager, but they provide people with enough oxygen if those people don’t have any lung disease. I can’t explain how your deep breaths cure the headache so rapidly. I am happy that they do, but I don’t believe the headaches are related to an oxygen deficit.

DEAR DR. DONOHUE: I have a very important question to ask you. Ever since my husband passed away five years ago, I have been eating TV dinners. My sister and I had a discussion about this, and she told me that it isn’t healthy to microwave my food. She said I won’t have an immune system left. Is she right? – L.T.

ANSWER: How can I break this to you gently and diplomatically without offending your sister? She’s all wet. That’s not diplomatic, but it is true. More vitamins and other nutrients are retained by cooking food with a microwave than by cooking it with most other methods. Microwaving food has no effect on your immune system.

You want to keep an eye on how much sodium (salt) is in your TV dinners. They can contain a lot. That’s something that could be an issue for you.

Dr. Donohue regrets that he is unable to answer individual letters, but he will incorporate them in his column whenever possible. Readers may write him or request an order form of available health newsletters at P.O. Box 536475, Orlando, FL 32853-6475. Readers may also order health newsletters from www.rbmamall.com