The Atlantic magazine's May 2010 issue features a very well written obesity article that I thought to share on here. As a recent graduate of a public health program the statistics and overall rates are not surprising, albeit, difficult to see and when placed in the context of future population growth and medical expenditures, still overwhelms.
It seems to me, that nutrition and physical activity policies are a great place to start. In the article, obesity and healthy weight legislation is often compared to anti-tobacco legislation and policies. In the US, at least, these policies (along with state and federal regulation) have reduced smoking rates. It then would seem that policies really are a smart way of targeting the many issues that pop up when discussing overweight and obesity, at least it provides some regulatory power both to states and at the federal level. Tackling the weight issue is going to be best pursued with healthy weight legislation (which I think sounds better than obesity legislation) and above all is going to have to be based on so many more factors.
For example, their are rigorous debates in shifting the blame towards the individual, and by extension also blames these enablers: big agriculture, food marketing, and the medicalization of treatments for overweight and obesity. Other issues of course discussed in the article include: calorie labeling, point of purchase calorie labeling, food deserts, food marketing to young children (and this definition really should be extended to include 0-18 years), school nutrition reform, taxation of junk foods, zoning laws and restrictions, and promoting access to healthy foods in low-income areas, among many others. Its difficult to link any one of these reasons as being the sole cause of overweight, and obesity, but there is stronger evidence linking multiple factors as risks in becoming overweight, which the article did a good job of explaining.
I think the outcomes of good policies weren't discussed as well in the article; it provided more the view of "single issue" policies such that taxation of sugar-sweetened beverages will reduce childhood overweight, instead of focusing on nutrition policies and programs currently in place, and that are working towards improving nutritional status among the population and reducing chronic diseases, and overweight and obesity. Further these "single issue" policies take greater blame, receive more media attention and coverage, and detract away from the issues at hand. I would like to see policies in place that address multiple issues, but that also work to support the current nutrition programs and policies that are already in place such as but not limited to...WIC the Women, Infants and Children Program, a supplemental food and nutrition program for low-income pregnant women and children up to the age of 5, the Centers for Disease Control's Preventative Health and Health Services Block Grants which provide yearly funding to every state and allows them to target their health issues (!), multiple Federal Food Programs which include the National School Lunch Program, the Fresh Fruit and Vegetable Program, the Child and Adult Care Food Program among others all working to increase access to healthy foods through public schools and other centers. These programs are never free from criticism, but they operate on federal and state budgets, and could be improved and supported by additional national and state policies. Overall these would increase momentum in changing the social norms associated with nutrition, health, and weight.
The US is the heaviest country in the industrialized world! The health care debate has certainly brought up health indicators within our population as being worse off than many other industrialized countries, of which many fall in Europe. The article really focused on increasing medical costs (which I think is a key issue in the obesity debate). There is this notion that Europe is more progressive and stricter with it's policies and regulatory powers. However the EU is also disjointed in many ways, having multiple cultures and languages represented in which social norms vary (food culture, access to health, smoking and tobacco use, and exercise). Comparing these indicators to US indicators seems futile, although not without merit, it seems inappropriate to use indicators for weight when comparing populations with very different governmental programs and oversight.
One thing I would like to see more of in the US is the built environment. There is plenty of healthy debate on zoning laws, and removing fast food, and limiting food advertising, but we really need to be thinking of how to rebuild physical activities into daily life. Biking and walking are HUGE forms of physical activity that have been replaced by cars, sprawl, urban decay, and poor mass transit. The overall amount of calories burned (and if those calories are from highly junk processed foods) by 1-2 hours stints in the gym is never going to reverse weight gain. This is the worst uphill battle of our generation. Without infrastructure that is provided by local, state and federal governments, policies that are put in place to improve nutrition and physical activities are going to stagnate. Which is also another great reason we need these policies in the first place!
Finally, the health care debate. Let's hope there is more universal access to those that really need it - to those that could not afford or maintain coverage, and that it drives preventative medicine further. Part of health care is being able to go to a doctor or health care professional when you need it, and having it be available to you at a clinic or within the community, at a reasonable cost. Escalating costs in chronic disease management exacerbate the problem, and as is, there isn't much available to those that really need it (as the author of the article points out having undergone bariatric surgery). Another factor driving medical costs upwards is going to a doctor or hospital when your symptoms are past the manageable phase and require immediate medical supervision. There needs to be access and support of chronic disease management at all levels of the population. Overweight and obesity are linked to many other metabolic disorders, ones that can be reversed or managed with modest, 5-10%, reductions in body weight. This is a realistic goal, but one that cannot be executed or maintained without medical and nutrition support. As a community health advocate and public health dietitian it is not appropriate to assume that task fall solely to the individual. There are great programs within communities that operate at the local public health department level that need further support, need further funding, need competent health professionals and political advocates that can vouch for their positive contributions in assessing and addressing their population-level health.
Showing posts with label public health. Show all posts
Showing posts with label public health. Show all posts
April 22, 2010
November 16, 2009
Muscle Energy Metabolism
The Department of Health and Human Services 2008 Physical Activity Guidelines recommends the following physical activity guidelines:
Children 6-17 should engage in 1 hour of moderate physical activity on most days of the week, and should perform bone strengthening or muscle strengthening exercises at least 3 days out of the week.
Adults 18-64 years old should engage in 2 hours and 30 minutes of moderate activity per week where at least 2 days out of the week activities are muscle strengthening and conditioning. OR adults should get 75 minutes of vigorous activity during the week where at least 2 days out of the week activities are muscle strengthening and conditioning.
Adults older than 65 years old should follow the recommendations (within their physical limits) for adults, and healthy pregnant women can follow the same for adults.
Why does it all matter? Exercise increases the oxidative capacity of muscle and inactivity causes reductions in the oxidative capacity of muscle. This oxidative capacity allows muscles to generate enormous amounts of kinetic energy. Skeletal muscle contributes to lipid and glucose homeostasis, and imbalances in this homeostasis can contribute to dysmetabolic disorders including insulin resistance, type 2 diabetes, dyslipidemias (increased LDL and VLDL's with reductions in HDL, and overall high trigylcerides). Exercise promotes weight stabilization, weight loss, and weight maintenance, blood glucose control, and calorie imbalance. In addition, exercise increases the capillary density promotiong the oxygen carrying capacity of muscles and can contribute to increasing the VO2 max. Exercises causes muscle fiber hypertrophy, or increases in muscle mass size. Oxidative capacity is increased by increasing the mitochondrial density, increasing TCA cycle enzymes, and increasing beta-oxidation enzymes. Together, these functions make exercise a necessity in maintaining and achieving health.
1. Why does skeletal muscle have a major impact on energy balance and body weight?
Ultimately, muscles perform mechanical energy, and their ability to do this relies on several biochemical processes and physiological functions. Muscles are the major sites of fatty acid oxidation and muscles take up glucose from the body to sustain the energy needed for glycogen synthesis, amino acid repair and muscle triacylglycerol synthesis. When you exercise you burn energy either as glucose or fatty acid oxidation (the substrate depends on the length, duration and type of conditioning) which leads to a caloric imbalance which can be related to body weight. Too little activity results in an imbalance of calories because calories in does not equal calories out. Weight is maintained (through many other mechanisms) but calories in = calories out.
2. How does skeletal muscle contribute to glucose and lipid homeostasis?
Muscle is dynamic tissue in that it performs a series of metabolic processes that has a wide range of effects. Essentially in healthy exercised muscles, glucose and lipids are readily and rapidly taken up into muscle. In unhealthy non-exercised muscles glucose and lipids interfere with cell signaling because so much is getting stored within the muscle, and more wants to get into the muscle. This imbalance can cause insulin resistance, dyslipidemia, cardiovascular disease, and other dysmetabolic states.
Glucose enters muscle cells via GLUT 4 receptors. These receptors translocate or move to the surface of the muscle cell and allow entry of glucose into the cell. GLUT 4 receptors mediate the entry of glucose in the cells for physiological function of the muscle cell. This contributes to glucose homeostasis because glucose is readily cleared from circulation and put into "storage." Problems occur when this balance is not achieved.
Skeletal muscle is a major site of fatty acid oxidation so healthy active muscles account for a large clearance of serum lipids including fatty acids, chylomicron, triaclglycerol, and VLDL's. After activity the muscle takes up lipids and uses the energy for glycogen resynthesis, muscle TAG synthesis and protein synthesis. This is caused by an increase in lipoprotein lipase activity. The way muscle contributes to lipid homeostasis is by burning energy, taking up lipids for fuel and refueling essential muscle functions (growth, repair). It also decreases VLDL and LDL, but raises HDL. These major functions contribute to lipid homeostasis.
Too much lipid or fat stored within the muscle as a direct effect of inactivity and calorie imbalance may result in insulin resistance and be on the causal pathway to developing diabetes. Lipids secrete adipokines, which are fat proteins that signal the general health status of the fat cell. Some adipokines such as TNFa are inflammatory markers and the presence of these in tissues where they should not normally be may contribute to abnormal cell signaling. The mechanism of action here is that the GLUT 4 receptor is not able to translocate to the cell surface, because of a defect in the insulin signaling pathway. Peripheral insulin resistance can be linked to skeletal muscle. Activity and exercise can reverse or improve insulin resistance by increasing or returning the oxidative capacity functions.
Muscles play an integral role in lipid and glucose homeostasis and chronic disease development. Exercising promotes the oxidative capacity of muscle tissue. This is directly linked to prevention of many chronic diseases including type 2 diabetes, metabolic syndrome, and cardiovascular diseases. In addition, exercise promotes weight maintenance and weight loss, improves circulation, promotes healthy blood pressure, strengthens the blood vasculature, promotes bone and skeletal health, and may prevent cancers of the breast and colon.
Children 6-17 should engage in 1 hour of moderate physical activity on most days of the week, and should perform bone strengthening or muscle strengthening exercises at least 3 days out of the week.
Adults 18-64 years old should engage in 2 hours and 30 minutes of moderate activity per week where at least 2 days out of the week activities are muscle strengthening and conditioning. OR adults should get 75 minutes of vigorous activity during the week where at least 2 days out of the week activities are muscle strengthening and conditioning.
Adults older than 65 years old should follow the recommendations (within their physical limits) for adults, and healthy pregnant women can follow the same for adults.
Why does it all matter? Exercise increases the oxidative capacity of muscle and inactivity causes reductions in the oxidative capacity of muscle. This oxidative capacity allows muscles to generate enormous amounts of kinetic energy. Skeletal muscle contributes to lipid and glucose homeostasis, and imbalances in this homeostasis can contribute to dysmetabolic disorders including insulin resistance, type 2 diabetes, dyslipidemias (increased LDL and VLDL's with reductions in HDL, and overall high trigylcerides). Exercise promotes weight stabilization, weight loss, and weight maintenance, blood glucose control, and calorie imbalance. In addition, exercise increases the capillary density promotiong the oxygen carrying capacity of muscles and can contribute to increasing the VO2 max. Exercises causes muscle fiber hypertrophy, or increases in muscle mass size. Oxidative capacity is increased by increasing the mitochondrial density, increasing TCA cycle enzymes, and increasing beta-oxidation enzymes. Together, these functions make exercise a necessity in maintaining and achieving health.
1. Why does skeletal muscle have a major impact on energy balance and body weight?
Ultimately, muscles perform mechanical energy, and their ability to do this relies on several biochemical processes and physiological functions. Muscles are the major sites of fatty acid oxidation and muscles take up glucose from the body to sustain the energy needed for glycogen synthesis, amino acid repair and muscle triacylglycerol synthesis. When you exercise you burn energy either as glucose or fatty acid oxidation (the substrate depends on the length, duration and type of conditioning) which leads to a caloric imbalance which can be related to body weight. Too little activity results in an imbalance of calories because calories in does not equal calories out. Weight is maintained (through many other mechanisms) but calories in = calories out.
2. How does skeletal muscle contribute to glucose and lipid homeostasis?
Muscle is dynamic tissue in that it performs a series of metabolic processes that has a wide range of effects. Essentially in healthy exercised muscles, glucose and lipids are readily and rapidly taken up into muscle. In unhealthy non-exercised muscles glucose and lipids interfere with cell signaling because so much is getting stored within the muscle, and more wants to get into the muscle. This imbalance can cause insulin resistance, dyslipidemia, cardiovascular disease, and other dysmetabolic states.
Glucose enters muscle cells via GLUT 4 receptors. These receptors translocate or move to the surface of the muscle cell and allow entry of glucose into the cell. GLUT 4 receptors mediate the entry of glucose in the cells for physiological function of the muscle cell. This contributes to glucose homeostasis because glucose is readily cleared from circulation and put into "storage." Problems occur when this balance is not achieved.
Skeletal muscle is a major site of fatty acid oxidation so healthy active muscles account for a large clearance of serum lipids including fatty acids, chylomicron, triaclglycerol, and VLDL's. After activity the muscle takes up lipids and uses the energy for glycogen resynthesis, muscle TAG synthesis and protein synthesis. This is caused by an increase in lipoprotein lipase activity. The way muscle contributes to lipid homeostasis is by burning energy, taking up lipids for fuel and refueling essential muscle functions (growth, repair). It also decreases VLDL and LDL, but raises HDL. These major functions contribute to lipid homeostasis.
Too much lipid or fat stored within the muscle as a direct effect of inactivity and calorie imbalance may result in insulin resistance and be on the causal pathway to developing diabetes. Lipids secrete adipokines, which are fat proteins that signal the general health status of the fat cell. Some adipokines such as TNFa are inflammatory markers and the presence of these in tissues where they should not normally be may contribute to abnormal cell signaling. The mechanism of action here is that the GLUT 4 receptor is not able to translocate to the cell surface, because of a defect in the insulin signaling pathway. Peripheral insulin resistance can be linked to skeletal muscle. Activity and exercise can reverse or improve insulin resistance by increasing or returning the oxidative capacity functions.
Muscles play an integral role in lipid and glucose homeostasis and chronic disease development. Exercising promotes the oxidative capacity of muscle tissue. This is directly linked to prevention of many chronic diseases including type 2 diabetes, metabolic syndrome, and cardiovascular diseases. In addition, exercise promotes weight maintenance and weight loss, improves circulation, promotes healthy blood pressure, strengthens the blood vasculature, promotes bone and skeletal health, and may prevent cancers of the breast and colon.
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