Clinical Perspectives
Obesity’s impact
A North American perspective By Paula Stewart The fact that North America is becoming increasingly obese is well recognized. What remains unclear is exactly why this has occurred in the latter half of the 20th century and the first half of the 21st-century. And what are the health implications of this growing epidemic?
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pidemiologic records indicate that the obesity epidemic really began with the end of the Second World War. At that time, food preparation became industrialized and convenience foods became the hallmark of the modern family. There was also the rise of fast food loaded with calories, carbohydrates, harmful fats, and production beef, i.e. beef produced with estrogen implants to increase weight at the market 1,2. Additionally, in the 1960s and 70s, there was an awareness of the role of cholesterol in heart disease and therefore the low-fat diet acquired widespread endorsement. The fats removed from foods in production were replaced by sugars, most often fructose3. Only now are we recognizing the negative effects of fructose (as well as artificial sweeteners) on weight gain and the development of obesity4. These changes in our food intake and food production, combined with changes in our physical activity have accelerated the obesity epidemic. North America has embraced an increasingly sedentary lifestyle. There has been the rise of energy saving aids such as escalators, elevators, driving, TV as a leisure activity, video games, and delivery services
USA and Canada BMI Classifications Classification
United States BMI Category (kg/m2)
Underweight <18.5 Healthy (normal) weight to height
18–24.9
18.5 – 24.9
Overweight
25.0 – 29.9
Overweight: (Class I)
25-29.9
30.0 – 34.9
Obese: (Class II)
30-39.9
35.0 – 39.9
Morbidly obese: (Class III)
40-49.9
< = 40
Super morbid obese
50 +
for everything imaginable. To effectively communicate about obesity there must be a recognized way to measure it. The body mass index (BMI), although flawed, is most widely accepted. This is the: weight (kilogram) / height (meters 2). There are slight variations in the classifications between the USA and Canada (see chart above). Changes in food production and an increased sedentary lifestyle have resulted in
Paula Stewart, MD, MS, CLT-LANA received her undergraduate and Master degrees from Stanford University. She attended medical school at the University of Minnesota in Minneapolis and completed her residency in Physical Medicine and Rehabilitation at the Mayo Clinic. Dr. Stewart co-founded LANA, The Lymphology Association of North America, and now serves as Vice president on the executive board. Dr. Stewart is currently in the process of developing a lymphedema outpatient clinic in the Chattanooga, Tennessee region.
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Canada BMI Category (kg/m2)
overweight levels increasing from 44% of the US population in 1960 to 66% of the population in 2004. Obesity increased within that same timeframe from 13% to 32%. More alarming is the increase in childhood obesity from 4% in 6 to 11-year-olds in 1971, to 19% in 20075. Childhood obesity is especially concerning because of the risk of associated health issues that increase with the length of time obesity has been present. Pediatricians are noting that rates of Type II diabetes, hypertension, fatty liver disease, gallstones and heart disease risk are soaring in children6. Complications of obesity in adults include increased mortality due to diabetes, heart disease, stroke and cancer, pregnancy complications, increased surgical risk, and psychological disorders such as depression. Increased annual medical costs related to obesity disorders are estimated to be in excess of $117 billion per year. Ly m p h e d e m a p a t h w a y s . c a 5
“Changes in food intake and food production combined with changes in physical activity have accelerated the obesity epidemic.”
Obesity is driving the evolution of disease and medical treatment. In adults we now recognize a common phenomenon called the metabolic syndrome, which is the development of belly fat causing subsequent health risks. Specifically, the metabolic syndrome is defined as the presence of three of the following risk factors: • E xcess waist circumference: – Men: Waist size greater than 40 inches or 102 cm – Women: Waist size greater than 35 inches or 88 cm • Hypertension • E levated triglycerides • L ow HDLs (high density lipoproteins or the good cholesterol) •H igh fasting glucose levels Treatment of obesity based on BMI For those who are overweight, with a BMI greater than 25 and less than 30, reducing calories can be effective. Multiple studies from Harvard, Stanford, Duke, and others have shown more weight loss, sustained longer, with corresponding reductions in triglycerides and increases in HDLs along with decreased fasting glucose and insulin and lower blood pressure on low carbohydrate diets. Classic examples of these types of diets are the Atkins diet and the ketogenic diet. In addition, those with a BMI greater than 25 and wishing to lose weight should increase activity. It is recommended that all persons exercise for 30 minutes, five days per week or 150 minutes per week. One quarter of Americans get no exercise at all. Additional benefits of exercise include increased energy, improved mental function, reduced risk of eight types of cancer, and improved insulin sensitivity and increased lean body mass. For those with Class II obesity with a BMI 6 Ly m p h e d e m a p a t h w a y s . c a
greater than 30, there are in addition to diet and exercise some pharmacotherapeutic agents that may be beneficial. However these same drugs may or may not be approved for use in Canada. There are agents that will prevent fat absorption from the gut and will result in approximately 3 kg of weight loss on average. Unfortunately, these agents very often cause significant diarrhea and can be quite expensive. There are also metabolism stimulants that reduce appetite. The average weight loss is approximately 5 kg with these agents; however, they have been shown to possess significant cardiovascular risks, rapid tolerance and dependence on these medications. Thus, if used, there must be close medical monitoring. There is a great deal of research currently underway looking at increasing the metabolism of fat burning through several different mechanisms. These are not currently available but may be a part of the solution in the future. For those with a BMI greater than 40, bariatric surgery is a potential solution (however there is variable access to this in Canada). This surgery reconfigures the anatomy of the stomach and the intestines to reduce caloric intake. There are restrictive procedures such as laparoscopic adjustable banding and sleeve gastrectomy. There are also malabsorptive procedures, which are represented by the biliopancreatic diversion. And there are combination procedures such as the Roux-en-Y gastric bypass. These surgical approaches can have dramatic results with 20 to 50 kg weight loss. The weight loss is often greater with the malabsorptive procedures than with the restrictive. Some of the additional benefits of bariatric surgery include: reduction of diabetes by 77%, reduction of hyperlipidemia in 83% of patients, elimination of hypertension in 66% of patients and elimination of obstructive sleep apnea in 88% of patients. Although beneficial, there are serious and widespread complications related to bariatric surgery including a 0.5% death rate, and persistent nausea and vomiting in more than 50% of patients undergoing the
procedure. Dumping syndrome occurs in more than 70% of those who have had bariatric surgery. Malnutrition, dehydration and other gastrointestinal complications are also common. Additional treatment approaches recently investigated include combining treatment for depression, which is widespread amongst those with obesity with a weight-loss program. By integrating behavioural weight-loss treatment with problem-solving therapy and antidepressant medications, studies have shown significant weight loss and reduction in depression a year later, compared to usual care. Another novel strategy has been to impose taxes on sweetened or artificially sweetened beverages. In Philadelphia, Pennsylvania in 2017, analysis of such a tax showed a 51% decrease in sales and consumption. In summary, prudent approaches to lifestyle changes that will impact health and weight control include the following: 1 Eat more small meals and eat at the same time; avoid late night snacking. 2 Watch portions. 3 Avoid sweetened beverages. 4 Avoid processed foods and attempt to eat mostly whole grains and fresh foods. 5 Exercise at least 150 minutes a week. The impact of obesity on lymphedema It is now known that lymphedema is present in the lower extremities when the BMI exceeds 53. That means that no antecedent lymphatic injury is necessary for the development of lymphedema. Obesity alone will cause lymphedema. Lymphedema in the upper extremities will occur when the BMI exceeds 100. There are multiple factors at play when obesity is present. Not only is venous pressure increased with excess weight, but also there is a mechanical factor. Very often the pannus will occlude venous and lymphatic return from the lower extremities. Additionally, the superficial lymphatics are more vulnerable to injury in the
Editor’s Note: Dumping syndrome is a condition that can develop after surgery to remove all or part of your stomach or after surgery to bypass your stomach to help you lose weight. Also called rapid gastric emptying, dumping syndrome occurs when food, especially sugar, moves from your stomach into your small bowel too quickly.
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fatty soft tissue present in an obese person. Thus, there can be breakage of these superficial lymphatics causing accumulation of additional lymphatic fluid in the extremities. These factors together will overwhelm the lymphatic system. The development of lymphedema within two years of surgery for breast cancer is associated with the patient’s BMI and patients must be counselled about this risk factor before treatment commences7,8. We know that weight loss can positively influence treatment of lymphedema. With reduction in the volume of the limb, it is easier to provide manual lymphatic drainage, bandaging and wrapping. Additionally, there is less likelihood of skin folds causing maceration skin breakdown and infection. A study in 2013 revealed that inducing obesity in a mouse model resulted in significantly reduced lymphatic transport, reduced lymph node uptake of interstitial fluid and abnormal lymph node architecture9. With weight loss there was normalization of lymph node size and function. Thus weight management may be an important means
Obesity rates in North America Percentage of the population with a Body Mass Index (BMI) of 30 or higher
*TERRITORIES: The Canadian study did not include the territories due to insufficient data. Statistics Canada suggests the territories have high obesity rates with Nunavut possibly as high as 28%. Sources: CDC.gov for American numbers: “Current and predicted prevalence of obesity in Canada: a trend analysis” published in CMAJ, 2014, for Canadian rates. Graphic by Amanda Shendruk (aeiq.ca).
of reducing the severity of lymphedema in at risk patients. Not only can obesity cause lymphedema, but lymphedema can also contribute to the accumulation of fatty tissue on the affected limbs. Lymph stasis results in the proliferation and hypertrophy of local fat cells. These areas of fatty deposition become chronically inflamed
and large numbers of macrophages are present. This results in phagocytosis and a classic appearance of “crown like” structures due to fat cell death10. It appears that this massive up regulation of fat cell deposition, which results from accumulation of lymphatic fluid in soft tissues, is driven by activation of certain genes such as peroxisome proliferator-activated receptor gamma (PPAR-g) and CCAAT/ Enhancer – binding protein alpha (CEPB-a). There is evidence that even small amounts of lymphatic accumulation in the soft tissues can result in promotion of adipose deposition in the subcutaneous space by increasing activation of adipose differentiation. This phenomenon is responsible for the typical appearance of Stage III limb with thickened skin, papillomas, and a dense fibrotic feel to the tissues11. The difficulties of lymphedema in an obese person or lymphedema caused by obesity are further highlighted by the challenges of treating such a person for their condition. Very often clinic equipment and furniture are certified only up to 350 pounds12. The waiting room furniture is inadequate to support the weight
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of patients who weigh more. Additionally, the patient will often require two therapists in order to receive effective therapy. One therapist to hold the limb so that a second therapist can provide adequate massage and bandage the affected limb. Finding garments to fit can be frustrating, and expensive; without appropriate treatment these patients are more vulnerable to cellulitis and wounds causing expensive hospitalizations, antibiotic usage, and increased morbidity and mortality. Effective treatment of a patient with both obesity and lymphedema must include weight loss in addition to complete decongestive therapy. Often the morbidly obese patient with lymphedema is unable to exercise safely on dry land but can manage pool walking which will provide the benefits of aquatic therapy in addition to meaningful exercise. Exercise alone
can change tissue composition and has been shown to reduce the amount of fatty deposition within the limb. This is in part due to reduction in lymphatic stasis due to exercise. Exercise alone can have a singular and positive affect on lymphedema and should be encouraged in all patients with lymphedema, especially those who are obese13. A low carbohydrate diet is recommended for all those who are in need of weight loss5. In some cases, surgical intervention is recommended to achieve meaningful weight loss. There are many side affects of surgical intervention and this decision should be carefully considered before consent. Once ideal body weight has been achieved, adopting a less restrictive diet can be pursued. In conclusion, there is a reciprocal relationship between obesity and lymphedema. As the
obesity epidemic increases worldwide, more persons are at risk of developing lymphedema without an initiating lymphatic injury. Further, those with lymphedema are at risk of worsening the impact of their lymphedema with the development of fibro-adipose tissue deposition in the affected limb as they experience increasing obesity. We know that fibrosis and adipose deposition impair lymphatic function thus resulting in a forward feeding loop. Weight loss can protect an obese person from developing pathological changes of the lymphatic system and reduce the impact of lymphedema in those who already suffer from it. LP A full set of references can be found at www.lymphedemapathways.ca
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