Dear Doctor: I’ve heard that the keto or paleo diets are good for weight loss and controlling blood sugar. Now I’m reading that a new study says they’re bad for your heart. What’s actually true?

Dear Reader: You’re referring to the ketogenic diet, also known as keto, and the Paleolithic diet, or paleo. Both are low-carb approaches to eating that are quite popular right now.

The paleo diet, also known as the caveman diet, draws from the foods that were presumably available to our Paleolithic ancestors. Since the Paleolithic era lasted 2.5 million years and ended about 12,000 years ago, the specifics of those diets are basically guesswork. But the core tenet of the paleo diet is that if a caveman didn’t eat it, neither should we. The result is a low-carb diet heavy on meat, with a limited amount of high-fiber fruit and vegetables. Since the Paleolithic era predates agriculture, things like grains, beans, cereals, legumes and dairy products, each of which require farming, don’t make it onto the plate.

The keto diet is even more restrictive. Its roots go back to the 1920s, when researchers found that a diet containing a very low proportion of carbohydrates and a very high proportion of fat appeared to reduce the number or severity of seizures in people with epilepsy. The goal of the diet is to put the body into a metabolic state known as ketosis. In ketosis, the body has depleted its stores of carbohydrates, its first go-to for energy, and instead begins to burn fat. This results in the creation of metabolic byproducts, including certain fatty acids, which are believed to ease the symptoms of epilepsy. Another side effect of ketosis is steady weight loss. The keto diet is heavy on protein and fat, including meat, fish, sausages, bacon, oils, butter, cheeses, nuts and seeds. The diet allows high-fiber carbohydrates, but in limited amounts.

It’s true that studies have associated both the paleo and keto diets with improved blood glucose control. They each also result in better appetite control and speedy weight loss. However, we don’t yet have enough reliable data about whether these diets promote long-term weight loss, or what health risks may be attached over time. The study you mentioned in your letter found a sharp increase in a certain blood biomarker linked to heart disease risk in participants who followed the paleo diet. At the same time, they had an increase in high-density lipoprotein, or HDL, the so-called “good cholesterol.”

Another study tied high-meat, low-carb diets to a drop in the diversity of the gut microbiome. An increase in the number of harmful bacteria was also observed. A separate analysis of a number of existing studies also found links between meat-heavy diets and an increase in cardiovascular risk. Bottom line -- we’re still sorting things out.

We understand the allure of the keto and paleo diets, but our advice continues to be a focus on whole rather than processed foods, lean proteins, a wide variety of fresh fruits and vegetables, whole grains, nuts and legumes, and healthful oils. Good for the heart, good for the gut and good for the planet.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: I’m 53 years old, officially in menopause -- and officially miserable. I’ve got hot flashes, headaches, insomnia and crazy mood swings, and it’s making me depressed. My doctor means well, but he doesn’t really listen and keeps suggesting hormone therapy. Is this really my only option?

Dear Reader: Although we tend to talk about menopause in terms of the physical changes and symptoms that occur during this time of life, the experience affects us emotionally and psychologically as well. Like it or not, there’s long been a stigma attached to the ending of a women’s fertile years, which can make going through menopause an isolating time. The good news is that there are a number of approaches for managing menopausal symptoms.

Menopause is the stage of life when a woman has stopped having a monthly menstrual period. The ovaries have stopped releasing eggs, and the body is no longer producing the hormones estrogen and progesterone. Production of testosterone drops at this time, too. These hormonal changes often cause a range of physical symptoms.

From what we see in our practices, up to 80% of patients experience some degree of symptoms during menopause. These include hot flashes, flushing and night sweats, which are known as vasomotor symptoms, and they can cause great discomfort and distress. Additional symptoms can include the insomnia and mood swings that you have been experiencing, as well as urinary incontinence, vaginal dryness, changes to skin tone and elasticity, and a drop in sex drive. Anxiety, depression, headache and changes to the ability to concentrate can occur as well.

When it comes to hot flashes, hormone replacement therapy -- which can be oral, topical or vaginal -- is certainly effective. If this seems the best route for a particular patient, we always focus on using the lowest dosage for the shortest amount of time. Studies have shown that low doses of the antidepressants Paxil and Effexor can also offer relief. Their use in menopause treatment has been approved by the U.S. Food and Drug Administration. Other medications may provide some women with relief from hot flashes are gabapentin, an antiseizure medication, and clonidine, a high blood pressure medication. Although black cohosh, an herb sold as a dietary supplement, can be effective in relieving menopause symptoms, it can have adverse effects that range from mild -- stomach upset and headache -- to severe, including liver damage.

We help our patients explore nonpharmacological lifestyle interventions before moving to hormone replacement therapy. Acupuncture and yoga can improve sleep, concentration and mood. Mindfulness, relaxation, hypnosis and cognitive and behavior therapies can relieve stress, anxiety and fatigue. Foods like soybeans, chickpeas, lentils, flaxseed, grains and beans, which contain plant estrogens, may help. There is also evidence that sugar and sugary foods can worsen hot flashes.

Post-menopausal women are at higher risk of osteoporosis and heart disease, so a balanced and healthy diet becomes even more important. We are fans of MenoPro, a free app offered by the North American Menopause Society, which is designed to help you and your physician identify problems and make treatment decisions.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctor: Is it true that eating ultra-processed foods raises your risk of cancer? I really don’t want to give up my comfort foods, like a handful of potato chips or an order of chicken nuggets every few weeks.

Dear Reader: If those chips and chicken nuggets make it onto your plate only occasionally and in limited quantities, you’re probably OK. But for people whose diets are high in ultra-processed foods, there’s no end to the bad news. Not only have recent studies tied these foods to an increased risk of cancer, they have been shown to play a role in heart disease, stroke and Type 2 diabetes.

So what is ultra-processed food? Cooking, canning, drying and freezing are ways to process various foods to make them edible, enhance flavor and preserve them for future use. But ultra-processed foods go several steps further. These are foods that have been repeatedly manipulated to alter their appearance, shape, flavor and texture, and that have been amped up with lots of added sugars, salt, hydrogenated fats, modified starches and artificial flavorings. Ultra-processed foods include everything from the packaged sweet and savory treats in the snack aisle, to convenience foods like canned soups and frozen entrees, to canned and bottled beverages, to much on the menus in fast-food chains.

The ingredient labels of these products start with recognizable foods like corn or wheat or potatoes, but quickly veer into the world of inorganic chemistry with a list of preservatives, colorings, stabilizers and additives. The nutritional information, meanwhile, is long on fat and sodium, and short on vitamins, minerals and fiber.

With an entire branch of food science dedicated to making these foods irresistible and addictive flavor bombs, it’s little wonder that studies show that up to half of calories consumed in the U.S. come now from ultra-processed food. And consumers pay a steep price. Close to 40% of Americans are obese. Type 2 diabetes has become an epidemic. As you mentioned in your letter, a small study found evidence that this type of eating is associated with a rise in cancer risk. Specifically, researchers associated a 10% increase in the proportion of ultra-processed foods in the diet with a 10% increase in the risk of cancer. The same study found that diets high in minimally processed foods like fruits, vegetables, milk and lean proteins, including fish, were associated with a lower cancer risk.

When it comes to diet, we’re realists. We want our patients to commit to eating habits that they can maintain over the long haul. For those in good health, we think a split of 80% being good about diet and 20% “cheat” is OK. For those with diabetes, hypertension or any kind of cardiac issues, the ratio drops to a minimum of 90% healthful eating and a maximum of 10% treat eating. When eating less healthful choices, our advice is to opt for whole food versions of your favorite treats and steer clear of ultra-processed foods.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10880 Wilshire Blvd., Suite 1450, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)