DEAR DR. DONOHUE: I have been taking a product for seven to eight months, at a considerable cost, to gain weight. I now weigh only 112 pounds. Am I wasting my money or clogging my arteries? I am 68. I have been examined. – R.L.

ANSWER: There is some important information missing from your letter. How tall are you? (Even if you are short, 112 pounds must put you on the very low side when it comes to body weight.) How much weight have you lost and in what period of time? (I take it you were heavier.)

Unexplained weight loss can result from some serious conditions. Cancer tops the list of those conditions. Cancer of the colon, lung, breast, ovary, prostate, kidney, bladder or blood (leukemia) might present with weight loss being the only sign.

Illnesses that interfere with the absorption of food come next on the list of weight-loss causes. Ulcerative colitis, Crohn’s disease, pancreatic troubles and celiac disease are examples of malabsorption conditions that lead to weight loss. Granted, they have other symptoms, but those other symptoms might be so subtle that you are overlooking them.

An overactive thyroid gland; infections such as TB and heart valve infection; congestive heart failure; and kidney disease are other conditions where weight loss can be prominent.

Even though you say you have been examined, I urge you to be re-examined, and perhaps a third time if a cause cannot be found on the second exam. You might need some more-involved diagnostic tests like X-rays, scans or scope exams.

The product label you sent is Ensure, a very reputable product for providing lots of calories in a small volume – 350 in 8 ounces. Don’t rely entirely on it. Eat other calorie-dense foods – foods that contain many calories in small amounts. One slice of pizza, for example, has 290 calories. Ensure is not clogging your arteries.

DEAR DR. DONOHUE: I had problems with hemorrhoids until I started taking Metamucil on a daily basis. I do try to eat lots of fiber as well. Is there any harm in taking this on a regular basis? – L.P.

ANSWER: Are you afraid of getting the laxative habit? Don’t be. I don’t consider Metamucil a laxative. It’s a “bulk-forming” agent. It increases fecal volume and keeps moisture in the feces just as fiber does. The soft, moist waste material can easily pass through and out of the colon.

Everyone needs between 25 and 35 grams of fiber a day – about an ounce or so. If you can’t get enough fiber with fruit, vegetables and whole grains, then something like Metamucil is fine. You can also buy bran, which is the outer coat of grains. Bran is the stuff removed during refining. It’s sold in some grocery stores and in just about all health food stores

A good investment is a little paperback that lists the fiber content of foods. You’ll find one in most bookstores. You can save yourself the money by asking your local librarian for a book that has the fiber count of foods in it.

The pamphlet on constipation and laxatives provides information on how to deal with irregularity and how to use laxatives wisely. Readers can order a copy by writing: Dr. Donohue – No. 504, P.O. Box 536475, Orlando, FL 32853-6475. Enclose a check or money order (no cash) for $4.50 U.S./$6.50 Can. with the recipient’s printed name and address. Please allow four weeks for delivery.

DEAR DR. DONOHUE: In my city, we have drivers who play their car stereos so loud that the floors and walls of my home vibrate from the noise. What are these drivers doing to their hearing? – A.H.

ANSWER: They’re destroying it. Continuous exposure to noise in the 90-decibel range can lead to irreversible damage to the hearing mechanisms. A loud shout is 90 decibels. Musicians in rock bands often experience hearing loss at young ages.

DEAR DR. DONOHUE: I had chickenpox as a child and have had shingles twice. I am 77.

My two daughters also had chickenpox. One daughter had a severe case. They are now 50 and 47. Is there anything they can do now to prevent shingles? – J.R.

ANSWER: Once the chickenpox virus gains entrance into the body, it never leaves. It stays hidden in nerve cells.

From time to time, the virus wakens from sleep and travels down the nerves to the skin, where it blossoms as the rash and pain of shingles. That usually happens later in life, and for most it is a one-time episode.

I wish there were a way to prevent the chickenpox virus from wakening. I know of none.

The severity of a case of chickenpox has little influence on the later development of shingles.

That ought to cheer your daughter who had the bad case.