For best results in weight loss, use moderate means

Q: I've heard that when you're on a diet and you decrease caloric intake by a lot, your body will start to consume muscle for energy. It that really true? How can you lose weight and not wind up losing muscle?

A: Discussions about losing weight typically focus on pounds, as in, "I want to lose 10 pounds." The important follow-up question here is: pounds of what? Work up a sweat with a vigorous set of tennis, and the scale will show you've immediately dropped a few pounds - of water weight. You'll gain it right back with your next beverage. (A quart of water weighs 2 pounds, in case you were curious.)

Diets that involve a drastic calorie cut do lead to weight loss, but participants wind up burning not only fat, but also significant amounts of lean muscle. That's a bad idea, because we rely on our muscles for both strength and endurance. Muscle tissue also plays an important role in resting metabolic rate.

The answer to the "pounds of what?" weight-loss question is, of course, fat. When we set a weight-loss target, the goal is to lose fat. Or, to view it in more useful terms, we want to achieve a more healthful ratio of lean tissue to fat. Achieving and maintaining a healthful weight has many benefits, including reducing the risk of diabetes, high blood pressure, coronary artery disease, depression and even certain cancers. And, while it's tempting to try some of the more extreme low-carb and high-fat diets that are now popular, which promise swift and painless weight loss, we believe a moderate approach yields better and more sustainable results.

To maximize fat loss and minimize the loss of lean muscle mass, you need a three-pronged approach. This begins with cutting back calories enough that you're operating at a slight deficit, but not to the point that your body thinks it's starving. A recent study in the Netherlands followed volunteers on a five-week diet of 500 calories per day, and those on a 12-week plan of 1,250 calories per day. Both groups lost the same amount of weight - about 19 pounds. However, the crash dieters lost almost three times as much muscle mass as those who followed the more moderate weight-loss plan.

To stay healthy as you lose weight, eat a wide range of fresh foods, with a focus on lean proteins, healthy fats and fresh fruits and vegetables. Take care to avoid simple carbohydrates and processed foods. You want a diet that, once you've reached your goal weight, you can continue to sustain.

Finally, it's important to incorporate two kinds of exercise into your daily life: cardio and resistance. Cardio helps to burn fat, and resistance maintains and builds the lean muscle mass that you want to conserve. Again, the aim here is a new set of habits that you're willing and able to maintain even after you've reached your goal weight.

Insulin is at the heart of both types of diabetes

Q: We keep hearing about Type 2 diabetes, and I'm embarrassed to say, I don't actually know what it is. What does it do, and how do I know if I have it?

A: To understand diabetes, we should first talk about glucose. That's the sugar our bodies make from the foods that we eat, and which our cells use as their main source of fuel. Glucose travels throughout the body via the blood, which is why it's also often referred to as blood sugar. However, it's not immediately available to the cells. That's where insulin, a hormone manufactured by the pancreas, comes into play. Insulin helps transport glucose from the blood into the cells, where it can be used as energy.

When someone has diabetes, it means that the insulin part of that energy equation isn't working properly. Either the body isn't manufacturing enough - or any - insulin, or it isn't responding properly to the insulin that is present. That leads to blood-glucose levels that are too high.

Over time, high blood levels of glucose are dangerous. Adverse health effects include damage to the circulatory system, vision problems, nerve damage, stomach or intestinal problems, slow healing, kidney disease and an increase in the risk of heart disease and stroke. Extremely high blood sugar levels can lead to coma, and even death.

In Type 1 diabetes, the pancreas makes little or no insulin. It often develops early in life, but can occur at any age. This type of diabetes is managed with diet and exercise, plus the use of medications and insulin.

Type 2 diabetes, once referred to as adult-onset diabetes, often develops later in life. It occurs when the body doesn't make or use insulin well. Type 2 diabetes often begins as insulin resistance, which is a condition in which the body stops responding properly to the insulin in the blood. This leads to a loss of the ability to control blood sugar.

Some people can manage Type 2 diabetes with diet and exercise alone. Others may also need medication or insulin to keep their blood sugar in control. Medication needs often change over time, so it's important for everyone with diabetes to have medical care.

Symptoms of Type 2 diabetes often develop gradually. They include persistent fatigue, increased thirst and urination, blurry vision, frequent infections, slow healing and unintended weight loss. Risk factors for developing the disease include being overweight, storing excess fat mainly in the abdominal region, a family history of diabetes, inactivity and being over the age of 45. These last two factors are associated with a drop in lean muscle mass, which some researchers think may play a role.

Type 2 diabetes used to be seen most often in middle-aged adults. Unfortunately, in recent years it has increasingly been seen in young adults, adolescents and even children. If you suspect you have developed the disease, it's important to see your doctor. Diagnosis is usually via a blood test. Treatment includes weight loss, changes to diet, exercise, blood sugar monitoring and, possibly, the use of medications or insulin.

Readers offer useful additions to previous columns

Welcome back to our monthly letters column. Like many of you, we're adjusting to shorter days and longer nights, and we are gearing up for the challenges of winter. This makes us even more appreciative of your staying in touch.

• Regarding a column about older adults and falling, a reader from Wallingford, Connecticut, asked us to add an important risk factor to the list. "Distractions were not noted in the article," he wrote. "Distractions can make a loose carpet, stairs and other obstacles even more dangerous. And distractions are spontaneous, which makes them even more dangerous. 'Once you take your eye off the ball, get ready for a fall.'" Agreed, and thank you.

On that same topic, a reader asked why we said that even a minor injury from a fall can affect quality of life. Although straining a muscle or twisting an ankle aren't in the league of a broken bone, they do cause pain, restrict movement and affect mobility. Each of those things makes getting through the day more of a challenge.

• A reader from Virginia Beach, Virginia, who started a fitness plan with her husband, wonders what qualifies as water. "I don't love having water early in the day, so I drink several cups of tea, all using the same tea bag," she wrote. "I count the tea as water, but my husband insists only plain water really counts. Do I need to switch?" Although caffeine has a mild diuretic effect, it's not nearly enough to offset the hydration of a cup of tea. Plus, you're stretching a single tea bag to three cups of tea, so, yes, your morning beverage ritual counts toward your daily water total.

• A recent column about vitamin D included guidelines for both vitamin supplements and sun exposure. "What about those of us who have had skin cancer, including melanoma, and need to avoid sunlight?" a reader asked. "How much vitamin D should we get from vitamin supplements?" This is important, so we're happy to repeat our advice: People with any history of skin cancer, or who are at risk for skin cancer, should rely on diet and vitamins for their daily allowance of vitamin D.

• In response to a column that referenced wigs for cancer patients, a reader from Nags Head, North Carolina, shared a discovery about medical expenses. "I was very surprised to learn wigs are a write-off on the annual returns!" he wrote. "Had we known, my wife probably would have gotten the more expensive natural hair wig she felt better in, rather than the cheaper wig she didn't really like. Please let your readers know this very important fact." You're correct that the costs of a wig for hair loss due to a medical condition, such as alopecia or cancer treatments, are tax deductible.

We'll close with a reminder that we can't offer a diagnosis or a second opinion, and we can't comment on specific treatments or medications. Also, we continue to get requests for previous columns. The good news is that a searchable archive is available online at uexpress.com/ask-the-doctors.

• Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu.