Category Archives: Health & Fitness explainer

Everyone knows what fat is. It’s where the extra calories you eat end up and the reason your clothes fit too tightly. But beyond that, it doesn’t do much, right? While fat, or adipose tissue, is a place to store excess energy, research shows that it also plays an active role in health and disease. In fact, your fat may be keeping you fat! The good news is that weight loss and regular exercise can reverse the negative health effects of excess body fat. This is the topic of my Health & Fitness column in the Aiken Standard this week.

Body fat is essential for storing extra energy, something that allowed our caveman ancestors to survive times when food was scarce. But fat cells have important biological functions beyond storing extra energy. It turns out that fat cells release chemical signals called adipokines that have effects on other organs and tissues.

For example, type 2 diabetes is strongly linked with obesity. Type 2 diabetes is a condition of high blood glucose caused, in large part, by cells not responding to the hormone insulin. Resistin, which is produced by fat cells, has the effect of causing insulin resistance in the liver and muscle, the two major places where excess glucose is stored. The result is high blood glucose, the hallmark characteristic of diabetes.

Fat cells also secrete adipokines such as leptin and TNF-alpha that promote inflammation and abnormal function of blood vessels. This is associated with atherosclerosis, the development of cholesterol-containing plaques that form in blood vessels. These plaques may be unstable and rupture, leading to clot formation that causes a heart attack. This is one reason why obesity is a major risk factor for cardiovascular disease.

The hormone leptin also plays an important role in regulating body fat stores. Leptin signals the brain about the amount of fat stored in the body. When body fat stores decrease, leptin stimulates appetite to increase energy intake and storage as fat; when body fat increases, appetite is reduced.

At least that is the way it is supposed to work. The effect of leptin on appetite is only a suggestion, and it is easy to eat despite it. The result is excess energy intake which leads to obesity. Worse, the brain develops a resistance to the high levels of leptin produced by the excess body fat and establishes a new “normal” level. When someone loses weight and leptin levels go down, the brain responds by increasing appetite. Is it any wonder why losing weight and keeping it off is so difficult?

The good news is that losing weight and body fat, no matter how difficult it can be, can reduce the negative effects of these adipokines. The even better news is that exercise can reverse some of this damage, even if you don’t lose weight. The reason is that, like adipose tissue, muscle produces chemical signals, too.

These myokines also have beneficial effects include improving insulin sensitivity and reducing inflammation. This is one way in which regular muscle activity (exercise) is thought to promote good health. Myokines can also counteract the negative effects of adipokines by creating a balance between the two opposing effects.

In fact, the myokines that are stimulated by exercise can have a greater effect than the adipokines. This helps explain why being obese but physically fit may actually be healthier than being a normal weight but unfit.

The bottom line is that excess fat is unhealthy and we are starting to understand the mechanisms that explain why. Losing weight is important for improving your health. And exercise may be even more important, so you should strive to be more active regardless of your body weight

If you want to learn more about the role of adipose tissue on health, these two articles are a good place to start (fair warning–they are high-sci):

George Ntaios, Nikolaos K. Gatselis, Konstantinos Makaritsis, George N. Dalekos. Adipokines as mediators of endothelial function and atherosclerosis. Atherosclerosis 2013;227(2): 216-221. http://dx.doi.org/10.1016/j.atherosclerosis.2012.12.029

Coelho M, Oliveira T, Fernandes R. Biochemistry of adipose tissue: an endocrine organ. Arch Med Sci. 2013;9(2):191-200. http://dx.doi.org/10.5114/aoms.2013.33181

Nutrition, exercise, and health information can be confusing. 
But it doesn't have to be that way.
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 drbrianparr@gmail.com | http://twitter.com/drbrianparr

When I write about health I routinely use terms like exercise, activity, and fitness. Some people have asked why I use these different words since they all have a similar meaning. That is an excellent question, since these terms are related they have different applications for health and wellness. This is the topic of my Health & Fitness column in the Aiken Standard this week.

Physical activity (PA) is defined as any movement produced by muscles that expends energy. Physical activity can be classified as occupational, what you do at work, and leisure-time, what you do in your free time. Occupational PA can vary greatly depending on the job, but it is low for most of us who spend much of our work day sitting. Leisure-time PA is all activity outside of work. This is of great interest to researchers since it reflects how we chose to spend our discretionary time. Physical activity can be measured by questionnaires or using devices such as pedometers, which count the steps you take, or accelerometers, which measure how much you move.

Exercise is a type of physical activity that involves planned, structured, and repetitive movement to improve or maintain physical fitness. Physical fitness, then, is a set of attributes that relate to the ability to perform physical activity and exercise. The components of physical fitness include endurance, strength, and flexibility. Basically, participation in physical activity and exercise improves your fitness and the greater your fitness, the better able you are to participate in physical activity. This is true for completing occupational tasks as well as traditional exercise, such as jogging or lifting weights.

The good news is that both physical activity and exercise have health and fitness benefits. Physical activity can vary in intensity, from light (slow walking), moderate (brisk walking), or vigorous (exercise like running). The 2008 U.S. Physical Activity Guidelines recommend that, at a minimum, all adults participate in moderate-intensity physical activity for 2 hours and 30 minutes per week or vigorous activity for 1 hour and 15 minutes per week along with strengthening exercises at least 2 days per week. You can meet this recommendation by going for a brisk walk for 30 minutes on 5 days per week or running for 25 minutes on 2 days per week or some combination of the two. Additional benefits come from doing more, either higher intensity or longer duration activity.

Vigorous exercise is the best way to improve fitness while moderate-intensity activity is strongly linked to health benefits. Fitness benefits result from adaptations in the heart and muscles, which get stronger and become better able to resist fatigue. These changes also lead to health benefits including lower blood pressure, cholesterol, and glucose as well as helping with weight loss and weight control.

Research suggests that health and fitness benefits also result from light-intensity or intermittent activity, especially if it replaces sitting. At home or at work, the more time you spend sitting, the poorer your health, even if you exercise every day. One study shows that getting off the couch and stepping in place during TV commercials results in nearly 25 minutes of activity per hour and burns about 150 calories, compared to 80 calories just sitting the entire time. You won’t get in great shape doing this, but it will increase your overall activity.

With this is mind, a good recommendation is to reduce sitting time in favor of light activity—stand while you read the paper or walk around while you talk on the phone—and participate in moderate or vigorous activity each day by going for a brisk walk or doing other exercises, including strength training.

Nutrition, exercise, and health information can be confusing. 
But it doesn't have to be that way.
What can I help you with?
 drbrianparr@gmail.com | http://twitter.com/drbrianparr