Sunday, May 29, 2016

Successful Weight Control

A recent article in the New York Times showed that people who succeeded in losing large amounts of weight – say from 430 pounds to 190 – were rarely able to stay at their new weights. Most of the dieters in the New York Times article had lost large amounts of weight rapidly, as contestants in The Biggest Loser television program.  When they began dieting they had normal metabolisms for their body size.  When they had lost weight, their metabolisms had slowed radically and their bodies were not burning enough calories to maintain their thinner sizes.  As the years went by their metabolisms did not recover, so they kept gaining back weight.  It seemed that their bodies were working to pull the dieters back to their original weights.  Investigators also found that the dieters had very low levels of leptin, a hormone made by fat cells that inhibits hunger.  They were unable to detect satiety (feeling full). 

This is discouraging news to people who want to lose weight for health reasons, such as having diabetes or certain kinds of heart disease.  Research is ongoing on ways to improve this situation. 

Are there other models of weight loss that would be more effective in the long term?  We will look at the National Weight Control Registry for ideas.  This organization was started by researchers from Brown Medical School and the University of Colorado, to look at people who have lost weight (at least 30 pounds) and kept it off for a year or more.  People enroll voluntarily; 80% are women, and 20% men.  On the average, weight loss has been 66 pounds, kept off for 5.5 years.  Most people report maintaining a low calorie, low fat diet (25% fat) and doing high levels of physical activity.  78% eat breakfast daily; 75% weigh themselves at least once a week; 62% watch less than 10 hours of TV per week; 90% exercise, on average, about 1 hour per day. Changing beverage consumption to low/no calorie sweetened drinks is felt to be very important for weight loss and maintenance by the participants. People in the registry varied in the amount of exercise they did, and in their dietary plans.  There was no ‘one size fits all’ formula being followed. 

Dr. Barbara Rolls at Penn State University has written several popular books on making weight loss easier.  Her latest is The Ultimate Volumetrics Diet.  She has looked at ways to change the amount of water in foods, thereby adding weight and volume but no calories. This is done by adding vegetables to each recipe, and making sure the food is tasty. The result, found in careful studies, was that people reduced their calorie intake by about 25%. In a trial of 700 people, she found that when people ate a diet that was less calorie dense (more vegetables included) they were eating significantly more food – about a pound more food a day – yet they were eating fewer calories and easily losing more weight. She has many good ideas, backed by research, that keep people healthy while losing weight slowly.  Read this book if you are frustrated about your weight.  Aim to lose weight slowly, so that your metabolism can adjust more easily,  And, whenever possible, keep moving! 
Sadja Greenwood, MD,MPH  back issues on this blog, including a column on Dr. Rolls & volumetrics,

Does Exercise Impact Your Cancer Risk? Some Recent Studies

Scientists at the National Cancer Institute, Harvard Medical School and other centers published a paper last week in JAMA Internal Medicine, showing that exercise appears to substantially reduce the risk of developing 13 different varieties of cancer.  The benefits seem to hold true even if someone is overweight.  The researchers looked at 12 large studies, pooled together, involving 1.44 million men and women.
They focused on specific information for each of those 1.44 million people about whether they exercised, how vigorously and how often. They also zeroed in on whether and when, after each study’s start, the participant had been diagnosed with any type of cancer. People who reported exercising moderately, even if the time that they spent exercising was slight, had significantly less risk of developing 13 different types of cancer than people who were sedentary. The researchers found a reduced risk of breast, lung and colon cancers, which had been reported in earlier research. But they also found a lower risk of tumors in the liver, esophagus, kidney, stomach, uterus, blood, bone marrow, head and neck, rectum and bladder. When the researchers compared the top 10 percent of exercisers, meaning those who spent the most time each week engaging in moderate or vigorous workouts, to the 10 percent who were the least active, the exercisers were as much as 20 percent less likely to develop most of the cancers in the study.
On the other hand, they found an increased risk of two types of malignancies — melanoma and slow-growing prostate tumors — among people who exercised the most. Those findings can most likely be explained by certain characteristics of active people, said Steven Moore, an investigator at the National Cancer Institute who led the study. “People who exercise generally go in for more checkups” than sedentary people, he said, resulting in more screenings for conditions such as so-called indolent prostate cancers. (There was no discernible association, positive or negative, between exercise and aggressive prostate tumors.) “They also often exercise outside,” he continued, “and are more prone to sunburns” than people who rarely work out, potentially contributing to a greater risk for melanoma.
Encouragingly, the associations between exercise and reduced cancer risks held true even when the researchers factored in body mass. People who were overweight or obese but exercised had a much lower risk of developing most cancers than overweight people who did not move much.
The authors cautioned that this was an observational study, so it cannot directly prove that exercise reduces cancer risks, only that there is an association between more exercise and less disease. It also relied on participants’ memories of exercise, which can be unreliable.  But even with those limitations, the findings sturdily suggest that exercise may help to reduce the risk of many types of cancer. Here in West Marin we have walking and hiking trails, dirt roads, gyms in Stinson and Point Reyes, tennis courts, classes at the community centers, and the ocean!  Let’s keep moving.

Sadja Greenwood MD, MPH  back issues on this blog

Sunday, May 1, 2016

The Latest about Your Spleen

Here are three things you should know about your spleen:  it filters your blood and holds a reserve of red blood cells in case of emergency; it is an important part of your immune system, and it is connected directly with the vagus nerve from the brain.

The spleen is an organ in the upper left part of the abdomen, left of the stomach, and protected by the rib cage. Think of it as fist shaped and about4 inches long.  It is the largest lymph node in the body.

Blood filtering:  as blood passes through the spleen old red cells are removed; their hemoglobin is broken down into amino acids and their heme (a molecule containing iron) is metabolized into bilirubin, removed by the liver and excreted in bile, feces and urine.  Iron is returned to the bone marrow, where new red cells are made. The spleen holds a reserve of red blood cells , used in pregnancy and in case of serious bleeding.  It also stores platelets, used for blood clotting, and white blood cells.

The spleen’s role in the Immune system: as blood flows through the spleen, it detects infectious particles such as bacteria and viruses.  Along with your other lymph nodes, the spleen puts out lymphocytes, a type of white blood cell that can produce antibodies to neutralize bacteria and viruses, and other substances toxic to the invading cells.  The spleen stores half the body’s supply of monocytes – another kind of white blood cell that moves to injured tissue and promotes healing.

The spleen’s connection with the central nervous system (the brain): the spleen is an important connection between the brain and the immune system.  In 2008, for the first time, fibers of the vagus nerve were found in the spleen.  The vagus nerve supplies parasympathetic fibers to most organs in the body and influences heart rate, digestive processes, sweating, speech and other functions.  In contrast to sympathetic nerve fibers (think fight or flight, excitement, anger), the parasympathetic branch of the nervous system is associated with relaxation, a slower heart rate,  lower blood pressure, and feelings of calm. Research is ongoing on vagus nerve stimulation in people with severe seizures, depression and severe pain.  Activation of the parasympathetic nervous system is also associated with decreased inflammation in the body. In situations of severe septic infections, stimulation of the vagus nerve gives increased survival in laboratory animals.

Long slow breathing, preferably through the nose, is one of the simple ways that you can derive the benefits of vagus nerve stimulation.  Most ways of meditation use this kind of breathing.   Establishing a daily practice of relaxation can lower blood pressure, help digestive disorders, decrease anxiety and possibly improve your immune system.  Research is ongoing in this area.

Take care of your spleen:  Most trauma to the spleen occurs in serious auto accidents.  Sometimes the spleen has to be removed as a result.  You can live without a spleen, but not as well.  Drive cautiously and defensively, banish road rage, wear your seat belt, and forget texting while you drive.  A healthy, intact spleen is worth the effort.
Sadja Greenwood, MD, MPH   back issues on this blog