Dear Doctors: I’ve been doing keto for a few months to lose weight. I’ve almost reached my goal, and I’m ready to go back to eating more carbs. Is there a good way to switch from keto back to a regular diet? I’m worried that when I eat carbs again, I’ll gain back the weight I lost.

Dear Reader: When someone follows a keto diet, it means that they are severely limiting their intake of carbohydrates. These are the building blocks from which the body manufactures glucose, which is its preferred source of fuel. With carbohydrates mostly removed from the diet, the body is forced to switch to Plan B, which is burning fat for energy. This is a metabolic process known as ketosis, which gives the keto diet its name.

In a ketogenic diet, carbohydrate intake drops to about 10% of total food intake. The remaining 90% of the diet is made up primarily of either fat or protein. The proportions depend on which type of keto plan you are following. There’s a high-fat and moderate-protein approach, which currently is the most popular form of keto. Another way to put the body into ketosis is with a high-protein and low-fat diet, which many people know as the Atkins, paleo or Zone diets. Whichever version of keto you choose, it’s the limits on carbohydrates that lead to the fat-burning state of ketosis.

Keto can be a good way to jump-start weight loss, but it has its drawbacks. With such strict limits on carbohydrates, eating a nutritionally balanced diet takes careful planning and sustained effort. And whenever you follow a restrictive diet for a period of time, returning to “normal” eating can be daunting. For the best results, it’s a good idea to make the switch gradually. Plan on taking several weeks to slowly add more carbohydrates -- and also more calories -- back into your daily diet.

It’s also important to pay attention to the two different categories of carbs -- simple and complex. Complex carbohydrates have more nutrients than simple carbs. They are also higher in fiber. Because they are made up of long chains of sugar molecules, they take longer to digest. Complex carbs are found in whole, unprocessed foods, including vegetables, whole grains, legumes, nuts, seeds, leafy greens and fruits.

Simple carbs, by contrast, are short chains of sugar molecules that absorb quickly. They include table sugar and sugar syrups. Simple carbs deliver calories but lack nutrients. They can cause a spike in blood sugar and leave you feeling hungry. Fruits, vegetables and other whole foods do contain simple carbs. However, the effect is mitigated by their higher fiber content.

As you move away from keto restrictions, steer clear of simple carbs. This includes sugar, soda, candy and other sweets, and highly processed foods. Instead, concentrate on a diet that is rich in lean proteins, healthy fats and complex carbs. A good model to follow is the Mediterranean diet. Call on the same discipline that allowed you to stick to keto, and choose high-quality carbs, lean proteins and healthy fat.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: I heard a story on the news about a connection between your gut microbiome and whether you like to exercise. Is that really true? If it is, I’d like to know how the scientists figured that out. Is there a way to change your gut to make you like working out?

Dear Reader: You’re referring to the results of intriguing new research that, not too surprisingly, has found its way into the headlines.

According to the study, which was published late last year in the journal Nature, certain bacteria living in the guts of mice appear to amp up their desire to be physically active. But it’s not the microbes themselves that make the mice want to exercise. Rather, they turned out to be a crucial part of a complex metabolic pathway associated with the release of dopamine, a neurotransmitter produced in the brain. Among dopamine’s numerous functions is a key role in pleasurable reward and motivation.

The study itself is fascinating. The researchers began with a question: What motivates the desire to be physically active? In search of an answer, they looked at the exercise habits of 200 mice. When placed in cages outfitted with treadmills and running wheels, the mice voluntarily exercised at different rates and for varying durations. While some ran long and often, others exercised only sporadically. Tests found no measurable differences in either the genetic makeup or the metabolisms of the high- and low-exercising groups of mice.

But when the scientists began to study the makeup of the rodents’ gut microbiomes, significant differences emerged. They administered a range of antibiotics to the mice, each of which selectively targeted certain gut bacteria. When the researchers measured activity levels after the gut bacteria had been eliminated, they found they had been cut in half. And when bacteria were systematically restored to the guts of the mice, only two types, Eubacteria and Coprococcus, were linked to a voluntary increase in exercise. But why?

Further study uncovered a link between those two bacteria and a metabolic process that leads to increased levels of dopamine in the brain. As we mentioned before, this neurotransmitter is associated with pleasure and reward. The takeaway was that the presence of those two types of bacteria allowed the mice to get a good jolt of dopamine, which led to the enjoyable physical sensation of a runner’s high.

It’s important to remember that this was a rodent study, and the results don’t translate directly to humans. But because our tiny cousins have biological and genetic characteristics that closely resemble our own, the results are promising.

The researchers have announced plans to look for similar metabolic pathways in humans, in which the presence of certain bacteria in the gut make exercise pleasurable. In the meantime, there are steps we all can take to enhance and preserve gut diversity. Eat a diet rich in a variety of fresh vegetables, fruit and leafy greens. Steer clear of added sugars and highly processed foods. And, even if you don’t naturally crave it, exercise.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)

Dear Doctors: My father is being treated for colon cancer. It was caught early, and his doctor is optimistic. The problem is, he’s getting really depressed. His doctor suggested a cancer support group. How do those work? Are they helpful? My dad isn’t very chatty and would need to be persuaded.

Dear Reader: Most of us are aware of the physical effects of cancer and cancer treatment, such as pain, exhaustion, nausea and hair loss. But the disease can take a steep mental and emotional toll, as well.

People who learn they have cancer often feel shock, anger, fear, sorrow and disbelief. Studies show that living with a serious disease can also leave someone with a profound sense of isolation. It arises because, in that moment of diagnosis, they have suddenly become different from everyone around them. With an urgent new schedule of doctor and clinic and hospital visits, they are separated from the familiar and reassuring rhythms of daily life. It’s a burden that, when added to the physical rigors of illness and treatment, often leads to the depression you’ve recognized in your father.

Cancer support groups are gatherings of fellow patients who, in sharing their thoughts, feelings and experiences, help each other cope. Many cancer patients say they find attending a support group helps them to deal with the numerous stresses of living with the disease. When talking to another person dealing with cancer, you don’t have to explain yourself. They already know what you’re going through. The daily physical, mental and emotional battles that are unique to cancer patients are common ground.

These groups are useful not only for emotional support, but also as a place to discuss the nuts and bolts of living with this disease. Patients help each other learn what to expect at each stage of treatment, how best to deal with doctors, how to manage side effects, strategies to stay strong and healthy, what foods to eat and where to find additional support services. Even something as seemingly inconsequential as advice on the best place to park can make daily life easier.

Your father doesn’t have to be a chatty person to take part in a support group. Participation, while welcome, isn’t required. The groups take place in person and also online. Some are for anyone with any type of cancer. Others are more specific, with a focus on a certain type of cancer or a certain age group. If your dad is open to exploring support groups, it would be a good idea to research what is available in your area. His medical team, and the clinics or hospital involved in his treatment, are a good resource. So is the National Cancer Institute’s data base. You can reach it by typing supportorgs.cancer.gov/home.aspx into your web browser.

If there are several options in your area, your dad can try them out to find the best fit. People often initially focus on how they may benefit from taking part in a support group. However, over time, they often find that helping others in their same situation is equally rewarding.

(Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Owing to the volume of mail, personal replies cannot be provided.)