Dear Doctor: Now that I've turned 50, I need to get a colonoscopy, but I just can't drink that disgusting prep solution. I've tried three different times, but I wind up so nauseated that I can't finish. Is there any other way to prepare?

Dear Reader: Let us reassure you that you're not alone in your struggles with preparing for a colonoscopy. Many of our patients say that the procedure itself is a breeze compared to drinking the solution. However, the preparation phase, which thoroughly empties the intestines, is vital to a successful procedure. Alternatives do exist, but they don't have the same effect, and therefore the results of the colonoscopy may not be as accurate or useful.

A colonoscopy is a procedure in which a gastroenterologist examines the inside of your colon and rectum using a long, flexible tube. Known as a colonoscope, it's equipped with a lighted tip and a camera. A colonoscopy can reveal whether colon tissues are irritated or swollen, if polyps have formed, and whether cancer is present. When polyps are found, a small wire loop on the colonoscope can be used to remove them.

For the best view, the colon must be clean. In fact, the state of your colon is the most important variable in the exam. Unless every last vestige of fecal matter has been eliminated, it's possible that polyps, which are small growths with the potential to become cancerous, or other abnormalities may be missed.

And here's where the dreaded prep solution comes into play. Available under brand names like Golytely, Colyte, Nulytely and Trilyte, these are powders that consist of a laxative, along with essential electrolytes like potassium and sodium. You mix the prep powder with 4 liters of water and drink it according to your doctor's orders.

The laxative, along with the volume of water, empties and cleanses the bowel. The added electrolytes compensate for those you are losing. Because electrolytes are basically salts, the prep solution tries to compensate for the taste with the addition of super-sweet flavorings. The mix of the two, as you have found, is challenging.

An alternative is a low-volume prep solution that you mix with significantly less water. You still have to drink a full 4 liters of fluid prior to the exam, but other than the 2 cups or so of the low-volume prep solution, the rest of that 4 liters can be water or any other clear liquid.

But -- and this is important -- low-volume prep solutions won't get the colon as clean. Also, there is the risk that your electrolytes can be sent out of balance. If there's really no other way, then discuss the low-volume prep with your doctor. And if you're willing to give traditional prep just one more go, try these tips:

-- Chill the solution well before drinking.

-- Sip it through a wide straw (it'll go faster) placed far back on your tongue.

-- Alternate gulps of solution with sips of something that tastes good.

It's not fun and it's not easy, but it's worth the investment because you'll get the best results from your colonoscopy. And, remember: When it's caught early, colon cancer can be successfully treated.

Dear Doctor: I am a 72-year-old male with no health problems other than GERD, which is well-controlled, and neurological problems associated with a back injury and surgeries. But in the past eight months, I've gone from 189 pounds to 142 pounds. Initially, I attributed this to stress over my wife's death six months ago, but now I don't know. A general physical, along with blood tests, CT scans of the chest and head, and X-rays of the chest have found nothing unusual. What should I do?

Dear Reader: I can understand why you're worried. Although unexplained weight loss is relatively common -- an estimated 15 to 20 percent of adults over 65 will have unintentional weight loss if followed over 10 years -- your degree of weight loss needs to be investigated further. After all, you've lost 25 percent of your initial weight.

In 15 to 37 percent of cases, cancer is the underlying cause of unintentional weight loss. The tests you list show that your doctor has searched for a possible malignancy and ruled out many cancers already. He or she should also rule out gastrointestinal malignancies. Together, a colonoscopy and upper endoscopy can detect cancers of the colon, stomach and esophagus.

Other potential causes of weight loss, seen 10 to 20 percent of the time, are stomach ulcers, inflammatory bowel disease or another gastrointestinal disease. I would expect some symptoms with this, such as poor appetite, stomach pain or diarrhea. Again, an endoscopy and colonoscopy can help rule out these causes.

As for infection, that too can be a cause of weight loss, but it's often associated with sweats and fevers, and the imaging studies or blood work likely would have found the cause. Similarly, blood tests would have identified high thyroid levels, uncontrolled diabetes and adrenal insufficiency, all of which can lead to weight loss.

Potential illness aside, studies have shown a consistent small degree of weight loss among people who lose a spouse, especially among older couples. For some, the weight loss is largely a side effect of difficulties in food preparation, especially if the person who passed had been the one preparing the meals. In those scenarios, taking a more active role in food shopping and preparation, or having a service deliver meals, are both good options.

But for many people, the cause is not focused on the practical, but is rather much deeper and more complex. The loss of a partner -- especially if it was unexpected -- is clearly traumatic. For that reason, I want to gently suggest that you not discount psychiatric causes as a reason for your weight loss.

Anxiety and depression can cause a decrease in appetite, which in turn leads to weight loss. Depression can also lead to isolation and dampen the desire for certain activities, such as exercise, which then leads to decreased muscle mass and weight loss. Bereavement groups, other family members or religious organizations can help manage these feelings, as can psychological therapy. For extreme cases, anti-depressants such as mirtazapine might be needed to help boost both mood and appetite.

Because many of the physical causes appear to have been ruled out, and the weight loss coincides with the passing of your wife, I would encourage you to get help adjusting to the changes you've experienced. Difficult though it may be, now is the time to focus on the life ahead.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I've read that "added sugars" should be limited to 10 percent of our total daily calories. But how are added sugars listed on nutritional labels? Are they part of the carbohydrates category? Does the sugar in a peach or a glass of milk count?

Dear Reader: Ah, nutrition labels. They're a wellspring of useful information and occasional confusion. But with a little decoding, you can use nutrition labels to set a course toward mindful and healthful eating.

Sugars are carbohydrates that are found in fruit and milk and, to a lesser extent, vegetables. They are either naturally occurring or are added to food during processing. Naturally occurring sugars are those that are present in a food, whether a banana, carrot, peach, glass of milk or spoonful of honey, exactly as harvested. Added sugars are those that are used in the cooking or processing of a food item to change its flavor.

One of the challenges to identifying added sugars is that they go by so many different names. A label that says sugar, brown sugar, raw sugar, molasses or honey is pretty easy. Move on to sugars like maltose or dextrose, and things are trickier.

One rule of thumb is that if a word ends in "ose," there's a good chance that sugar is involved. Fructose, glucose, high-fructose corn syrup, lactose and sucrose -- all these are sugars. One exception is sucralose, an artificial sweetener that goes by the name Splenda. A bit trickier are ingredients with the word "syrup," like cane syrup, agave syrup and corn syrup. And if you see something like "fruit concentrate," that's also an added sugar.

You're absolutely right that when it comes to added sugars, the federal Centers for Disease Control and Prevention (strongly) suggest that we keep them to less than 10 percent of our daily diet. That means someone who eats 2,000 calories per day should limit added sugars to less than 200 calories per day. Considering that each gram of sugar has 4 calories, that's still a hefty allowance for sweets.

So how do you track added sugars? First of all, naturally occurring sugars do not count toward the total. If you eat a fresh pear, even though it contains 17 grams of sugar, you have eaten zero grams of added sugars. Artificial sweeteners also do not factor in the added sugars count.

The challenge comes with existing nutritional labels, which don't plainly identify added sugars. The "sugars" or "carbohydrates" designation indicates both naturally occurring and added sugars. That means you have to do a bit of sleuthing. Read the list of ingredients for telltale sugars. The higher up they appear on an ingredients list, the greater percentage of added sugars the product contains. Check serving size -- remember 4 calories per gram of sugar -- and then guesstimate.

If you think this is a crummy way to track added sugars, we heartily agree. The good news is that the FDA has ordered a new nutritional label that clearly states the grams of added sugars. The bad news is that although the label was approved in 2016, it won't make its debut until July 2018.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o Media Relations, UCLA Health, 924 Westwood Blvd., Suite 350, Los Angeles, CA, 90095. Owing to the volume of mail, personal replies cannot be provided.)