Category: SPORT

Various versions of low-carbohydrate diets have been popular for many years. The details of what is allowed and what is not vary quite a bit, and the amount of carbohydrates also differs. The common impression is a plate devoid of bread, pasta, and starchy vegetables, piled high with bacon, meat, eggs, and cheese, and maybe a small amount of vegetables and nuts. Due to the high saturated fat content in these diets, doctors and nutritionists worry about their potential adverse effect on cardiovascular disease.

Recently, a new study published in the American Journal of Clinical Nutrition has found that a low-carbohydrate, high-saturated fat diet might not be as bad as we feared. That sounds like good news, but is it that simple? Let’s take a look at what this randomized diet trial did and what the results really mean.

What did the study actually involve?

The 164 participants in this study were all considered overweight or obese, and had just finished a weight loss trial to lose 12% of their body weight. They were randomly assigned to one of three diets containing different proportions of carbohydrates and fat. Protein content was kept the same (at 20% calories) for everyone. They were not planning to lose any more weight.

The three diets were:

• Low carbohydrates (20%), high fat (60%), saturated fat comprising 21% of calories: this resembles a typical low-carbohydrate diet and has much higher saturated fat than recommended.
• Moderate carbohydrate (40%), moderate fat (40%), saturated fat comprising 14% of calories: this is not far from the typical American diet of 50% carbohydrates and 33% fat, and it is quite similar to a typical Mediterranean diet, which is slightly lower in carbohydrates and higher in fat than an American diet.
• High carbohydrate (60%), low fat (20%), saturated fat comprising 7% of calories: this meets the recommendation of the Dietary Guidelines for Americans and is a typical high-carbohydrate diet, including a lot of grains, starchy vegetables, and fruits or juices.

The study participants received food prepared for them for 20 weeks. They had their blood measured for a number of risk factors of cardiovascular disease, and a lipoprotein insulin resistance (LPIR) score was calculated using a number of blood markers to reflect the risk for cardiovascular disease. (LPIR is a score that measures both insulin resistance and abnormal blood cholesterol all in one number, and it is used for research purposes.)

The researchers found that at the end of eating these diets for five months, the low-carbohydrate group, which also had consumed the highest amount of the presumably worrisome saturated fat, did not have the worst cardiovascular disease blood markers. The amount of good and bad cholesterol in the blood was not different from the other groups. In fact, the LPIR cardiovascular risk score and two other disease markers (Lp(a) and adiponectin) also were improved the most in this group. This seems to suggest that we can go ahead and not worry about the saturated fat that typically goes with a low-carbohydrate diet.

What were the participants actually eating?

Alas, those who were eating the low-carbohydrate diet were not piling up their plate with steak and bacon, and those eating the high-carbohydrate diets were not drinking unlimited soda. All three diets were high in plant foods and low in highly processed foods (it is easier to stick to a diet when all the food is prepared for you). Even the low-carbohydrate group was eating lentils, a good amount of vegetables, and quite a bit of nuts.

And although the diet was quite high in saturated fat, it was also high in the healthy poly- and monounsaturated fats as well. The meat was a combination of higher amounts of healthy (salmon) and a small amount of unhealthy (sausage) choices. In addition, fiber intake (at about 22 grams/day) was slightly higher than the average American intake (18 grams/day). Overall, except for saturated fat being higher than recommended, the diet as a whole was quite healthy.

What is the take-home message?

It seems that among a relatively young and healthy group of people (the average age of those who completed the study was 45 years old), higher amounts of saturated fat in the context of a healthy diet do not seem to adversely affect certain cardiovascular risk markers in the short term. How it would affect actual disease — such as heart attack, stroke, and diabetes — in the long run is unknown. However, there is ample evidence showing that a diet that consists of healthy foods and has moderate amounts of carbohydrate and fat can lower the risk of these diseases.

Preventing diseases is a long-term process; a healthy diet must not only be effective, but it should also be flexible enough for people to stick to in the long run. Therefore, a healthy diet with moderate amounts of healthy carbohydrates and ample healthy fats may be the easiest with which to achieve good health. Lower-carbohydrate diets might be promising, but further long-term testing is needed.

Get expert advice on gathering safely from Harvard Health Publishing. Spoiler alert: vaccination is key to helping keep everyone healthy. Below, our faculty contributors share their own plans and advice for safely enjoying the holidays this year while answering three important questions.

Roger Shapiro, MD

Associate professor of immunology and infectious diseases, Harvard T.H. Chan School of Public Health, Boston

What are your plans this year for gathering — or not gathering — with family or friends during Thanksgiving and other winter holidays, and why?

Unlike 2020, my family will be gathering for Thanksgiving in 2021. Everyone in the family is vaccinated, and most are now boosted as well. We are all comfortable with the protection that being vaccinated brings, and there is agreement that if a COVID-19 exposure were to occur, it is unlikely to cause severe illness.

What advice can you offer people planning to gather in person to reduce the chance of getting or spreading the virus that causes COVID-19?

Everyone who can get vaccinated should be vaccinated, and those who qualify for a booster should get one. Children 5 to 11 may not have their second shot by Thanksgiving but can certainly be fully vaccinated by Christmas. If there are unvaccinated members of your family, your situation is no different than in 2020: gathering is unsafe for the unvaccinated because the first exposure to this virus can be lethal without protection from a vaccine. Additionally, people who are unvaccinated are more likely to be infected before traveling, so they are more likely to bring the virus to the table, possibly causing illness (even if mild) among those who are vaccinated. For families that are all vaccinated and wishing to further reduce the possibility of transmission, taking a rapid antigen test prior to gathering can add a layer of protection.

For people planning to travel to gatherings, what would you advise?

If you are all vaccinated, enjoy the return to a normal holiday season. Vaccines are your main source of protection. If you want to add additional protection, you can consider using rapid antigen tests just before gathering to confirm that everyone is negative. If there are immunocompromised members of your family who may not be fully protected by a vaccine, you should discuss the risks case-by-case with your doctor.

Suzanne Salamon, MD

Chief of clinical programs in gerontology, Beth Israel Deaconess Medical Center, Boston

What are your plans this year for gathering — or not gathering — with family or friends during Thanksgiving and other winter holidays, and why?

Let me start by saying my 99-year-old mother lives with us, and even though she’s had her third shot of the COVID vaccine, I’m very concerned about immune status. I also have a two-year-old granddaughter who cannot yet get the vaccine. So, everyone’s immune status is not equal. Certainly older people, even those who’ve had their third shot, may not have the same immune status as a 35-year-old.

We have really curtailed the size of our Thanksgiving dinner to under 10 people, since the CDC recommends smaller groups. Nobody wants to see people sitting at home alone during the holidays, but we have to make it as safe as possible for those who are there.

What advice can you offer people planning to gather in person to reduce the chance of getting or spreading the virus that causes COVID-19?

COVID cases are on the rise now in many places, even though a month ago the numbers were trending down. Unfortunately, we need to be more vigilant once again.

Many people are afraid to insult family and friends by asking them about vaccine status before they come. Tell people that you really want to see them, but some family or friends may be immune-suppressed or at higher risk if they get COVID-19, and you’re trying to make the gathering safe for everyone. That’s why I’d ask people to let you know their COVID vaccine status. Even after the two-vaccine series, research is showing diminished antibodies after six months, which may put people at higher risk for getting and/or spreading the virus. I would ask people who are not vaccinated not to come.

When people gather, ventilation is really important in reducing the concentration of any virus that might be present. Have the gathering outside or on a screened porch, if at all possible. We hosted Thanksgiving last year in our garage. We left the garage doors open and set up small tables and little space heaters for warmth. People could be social yet stay separated, and ventilation was great. You can decorate small tables with colorful plastic tablecloths and candles, even put down a rug. If you’re inside, windows and doors can be kept open, which will help move the air around. Have some small space heaters and sweaters available.

Ask everyone to bring a mask, or keep a box of masks available. Wear masks while you’re all chit-chatting until you sit down to dinner. In the bathroom, have a roll of paper towels or paper guest towels rather than a cloth towel, and leave the fan on for ventilation.

For people planning to travel to gatherings, what would you advise?

Planes are thought to be very safe. In the air terminal, sit apart from people. Keep your mask on during the flight.

Traveling by car is pretty safe. If you get out to go to the bathroom or get coffee, wear a mask and wash your hands. Traveling by bus or train is tricky, because even though there is a mask requirement, people will take off their masks. Be sure to wear your own mask. I personally double-mask. Two surgical masks block out a lot and can be a bit more comfortable than the N95 masks we wear in the hospital. A plastic face shield over the mask may be a good idea for added protection.

John J. Ross, MD

Hospitalist with specialty in infectious diseases, Brigham and Women’s Hospital, Boston

What are your plans this year for gathering — or not gathering — with family or friends during Thanksgiving and other winter holidays, and why?

We are having an unmasked, multigenerational, fully-vaccinated, traditional Thanksgiving dinner at my in-laws, just like the Before Times.

What advice can you offer people planning to gather in person to reduce the chance of getting or spreading the virus that causes COVID-19?

Everyone in attendance should have a primary COVID vaccination. Getting vaccinated against COVID reduces the risk of hospitalization or death due to COVID by more than 90%. It also reduces your risk of death from any cause. People who are eligible for booster shots should get them. That includes anyone over 65, and people over 18 with underlying medical conditions, high occupational risk, or those who live in high-risk settings such as group homes, shelters, and long-term care facilities.

Certain vaccinated people are more likely to get breakthrough COVID. This includes people of advanced age, and those with serious medical conditions or weak immune systems. These people should be extremely cautious around those who are not vaccinated or partly vaccinated. I would recommend that they mask around unvaccinated people, physically distance, and use extra ventilation (opening windows, or ideally moving the whole shebang outdoors). Rapid antigen tests may also be helpful in the setting.

For people planning to travel to gatherings, what would you advise?

For those who have long distances to travel, I would recommend flying if possible. Airplanes have excellent ventilation, and masks are mandatory. While masks are also required on trains, they are not as well ventilated as planes, and train travel has been associated with significant COVID risks.

Amy Sherman, MD

Division of infectious diseases, associate physician, Brigham and Women’s Hospital, Boston

What are your plans this year for gathering — or not gathering — with family or friends during Thanksgiving and other winter holidays, and why?

This Thanksgiving, my fiancé and I are driving to New Jersey and New York (with our dog!) to visit our families. We will have dinner with 14 others from my close family — larger than last year’s Thanksgiving, but smaller than pre-COVID years. Everyone has been vaccinated, and most have received a third dose. We will then visit with my fiancé’s 94-year-old-grandma, choosing to see her independently instead of bringing her to a large gathering.

Although no measures can absolutely make an indoor gathering 100% safe, we will apply layers of protective measures to reduce risk, with vaccinations as the base layer. Additionally, everyone will get tested for the virus that causes COVID-19 before gathering, limit exposure risks in the week before Thanksgiving, avoid public transportation, and drive instead of flying. When we’re together, we’ll spend time outdoors as much as possible. Maybe this year will bring new traditions — an outdoor bonfire instead of nighttime movie marathons, or Friday morning jogs instead of Jazzercise with my aunt!

What advice can you offer people planning to gather in person to reduce the chance of getting or spreading the virus that causes COVID-19?

We are in a much better place this year compared to last year. Connecting with family and friends is important for our mental health and well-being. However, we still need to be cautious, especially when gatherings include people who are older, immunocompromised, or at risk of severe COVID-19. We also have seen recent outbreaks in school-age kids who are not yet vaccinated. I would encourage your family and friends to get vaccinated if they haven’t already. For those family members at higher risk, consider smaller and more intimate gatherings, or do hybrid in-person/Zoom meetings. And layer up with the other risk reducing strategies I suggested!

For people planning to travel to gatherings, what would you advise?

Avoid public transportation if possible. If this is not possible, wear a mask on the bus, train, or airplane, even if you’ve been vaccinated. Vaccinations decrease the severity of disease, but you still could become infected and transmit the virus to others.

Read more advice on gathering for winter holidays this year, such as who can and should get a COVID-19 vaccine booster, whether to take a rapid test or PCR test before spending time with family or friends, how to navigate tricky relationships, and healthy eating through the holiday season.

So many physical abilities decline with normal aging, including strength, swiftness, and stamina. In addition to these muscle-related declines, there are also changes that occur in coordinating the movements of the body. Together, these changes mean that as you age, you may not be able to perform activities such as running to catch a bus, walking around the garden, carrying groceries into the house, keeping your balance on a slippery surface, or playing catch with your grandchildren as well as you used to. But do these activities have to deteriorate? Let’s look at why these declines happen — and what you can do to actually improve your strength and coordination.

Changes in strength

Changes in strength, swiftness, and stamina with age are all associated with decreasing muscle mass. Although there is not much decline in your muscles between ages 20 and 40, after age 40 there can be a decline of 1% to 2% per year in lean body mass and 1.5% to 5% per year in strength.

The loss of muscle mass is related to both a reduced number of muscle fibers and a reduction in fiber size. If the fibers become too small, they die. Fast-twitch muscle fibers shrink and die more rapidly than others, leading to a loss of muscle speed. In addition, the capacity for muscles to undergo repair also diminishes with age. One cause of these changes is decline in muscle-building hormones and growth factors including testosterone, estrogen, dehydroepiandrosterone (better known as DHEA), growth hormone, and insulin-like growth factor.

Changes in coordination

Changes in coordination are less related to muscles and more related to the brain and nervous system. Multiple brain centers need to be, well, coordinated to allow you to do everything from hitting a golf ball to keeping a coffee cup steady as you walk across a room. This means that the wiring of the brain, the so-called white matter that connects the different brain regions, is crucial.

Unfortunately, most people in our society over age 60 who eat a western diet and don’t get enough exercise have some tiny "ministrokes" (also called microvascular or small vessel disease) in their white matter. Although the strokes are so small that they are not noticeable when they occur, they can disrupt the connections between important brain coordination centers such as the frontal lobe (which directs movements) and the cerebellum (which provides on-the-fly corrections to those movements as needed).

In addition, losing dopamine-producing cells is common as you get older, which can slow down your movements and reduce your coordination, so even if you don’t develop Parkinson’s disease, many people develop some of the abnormalities in movement seen in Parkinson's.

Lastly, changes in vision — the "eye" side of hand-eye coordination — are also important. Eye diseases are much more common in older adults, including cataracts, glaucoma, and macular degeneration. In addition, mild difficulty seeing can be the first sign of cognitive disorders of aging, including Lewy body disease and Alzheimer’s.

How to improve your strength and coordination

It turns out that one of the most important causes of reduced strength and coordination with aging is simply reduced levels of physical activity. There is a myth in our society that it is fine to do progressively less exercise the older you get. The truth is just the opposite! As you age, it becomes more important to exercise regularly — perhaps even increasing the amount of time you spend exercising to compensate for bodily changes in hormones and other factors that you cannot control. The good news is that participating in exercises to improve strength and coordination can help people of any age. (Note, however, that you may need to be more careful with your exercise activities as you age to prevent injuries. If you’re not sure what the best types of exercises are for you, ask your doctor or a physical therapist.)

Here are some things you can do to improve your strength and coordination, whether you are 18 or 88 years old:

• Participate in aerobic exercise such as brisk walking, jogging, biking, swimming, or aerobic classes at least 30 minutes per day, five days per week.
• Participate in exercise that helps with strength, balance, and flexibility at least two hours per week, such as yoga, tai chi, Pilates, and isometric weightlifting.
• Practice sports that you want to improve at, such as golf, tennis, and basketball.
• Take advantage of lessons from teachers and advice from coaches and trainers to improve your exercise skills.
• Work with your doctor to treat diseases that can interfere with your ability to exercise, including orthopedic injuries, cataracts and other eye problems, and Parkinson’s and other movement disorders.
• Fuel your brain and muscles with a Mediterranean menu of foods including fish, olive oil, avocados, fruits, vegetables, nuts, beans, whole grains, and poultry. Eat other foods sparingly.
• Sleep well — you can actually improve your skills overnight while you are sleeping.