There are many reasons to maintain a healthy body weight, but preventing the chronic swelling condition known as lymphedema is probably one that you’ve never heard of.
In fact, there’s a good chance that your family doctor hasn’t heard of the connection between obesity and lymphedema either. This is not surprising. The link between obesity and lymphedema was discovered only relatively recently, and this type of swelling can be difficult to diagnose in individuals who are obese. When swelling is noticed, venous insufficiency is usually the go-to diagnosis for physicians.
This is a potentially harmful misstep; missing or incorrectly diagnosing lymphedema can lead to worsening of symptoms and potentially permanent health complications – including irreversible lymphedema.
What is lymphedema?
Lymphedema is chronic swelling in an area of the body, usually a limb, caused by a failure of the lymphatic system to adequately remove ‘lymph’ fluid.
The circulatory system delivers oxygen and nutrient rich blood throughout the body. A fluid called ‘plasma’ leaves the blood to deliver nutrients to cells, and to collect cellular waste. Most but not all of this fluid returns to the blood stream and is pumped back to the heart through the veins. The remaining fluid, called ‘lymph’, is collected by lymphatic vessels and ultimately dumped back into the blood stream to rejoin the body’s circulatory system.
The circulatory and lymphatic systems work together to continuously balance fluid levels throughout the body. If the lymphatic system fails to function normally in an area of the body, the circulatory system cannot compensate for the excess fluid, and swelling occurs. When left untreated, lymph fluid accumulation will progress and can cause disfiguring swelling, tissue changes including a hardening of the skin and underlying tissues, susceptibility to infection and skin ulcers, reduced range of motion in the limb, and diminished quality of life.
There is currently no cure for lymphedema, patients with lymphedema must instead manage and monitor their symptoms on an ongoing basis.
Obesity and lymphedema: an underappreciated health hazard
Lymphedema usually occurs as a side effect of cancer and cancer treatment. Tumor growth, surgery, radiation and chemotherapy can all be sources of damage to the lymph vessels and lymph nodes that comprise the lymphatic system. Most people are unaware that the lymphatic system can also be damaged by excess fat deposits.
A link between obesity and lymphedema has long been hypothesized. For example, increased body weight has been shown to increase the risk of lymphedema in breast cancer patients (ref. 2) whose cancer treatment predisposes them to developing it. But the first strong evidence of a connection between obesity and lymphedema in otherwise normal individuals appeared in a 2012 study published in the New England Journal of Medicine (ref. 1).
These researchers found that every participant in their study who had a body-mass-index (BMI) of 59 kg/m² or more (but who were otherwise healthy) presented with insufficient lymphatic flow in the lower extremities – a hallmark of lymphedema.
How obese do you need to be before you get lymphedema?
In 2015 the same research group sought to answer this question using a group of patients referred to their center for suspected lower-extremity lymphedema (ref. 3). The authors examined 51 patients with a BMI over 30, and with no other pre-existing condition or risk-factor associated with lymphedema. All patients with a BMI over 60 had an abnormal lymphoscintigram (a test for lymph flow) characteristic of lymphedema, while all patients with a BMI under 50 had normal lymphoscintigrams. This suggests that there may be a threshold of 50-60 BMI, above which lymphedema of the legs may become all but a certainty.
But this threshold also depends on other factors, and so for some individuals the BMI threshold for developing lymphedema would be expected to be much lower than 50-60. This group would include people with undiagnosed preexisting lymphatic deficiencies arising from cancer treatment, injury, or who were born with a congenital lymphatic malformation (but who are currently symptom free). For this group a much more modest increase in body weight might be enough to tip the scales in favor of developing lymphedema.
The existence of preexisting lymphatic deficiencies in otherwise outwardly healthy individuals might help explain an interesting observation reported in this study: in 25% of cases of lymphedema believed to be caused by obesity, lymphedema was found to affect only a single leg, rather than both as might otherwise be expected.
How common is lymphedema in people who are obese?
Studies suggest that the frequency of lymphedema in overweight individuals who are otherwise healthy should increase with body mass index (BMI). Having a BMI of over 30 appears to place you at heightened risk of lymphedema, whereas if you have a BMI of 50-60 or more, you are at very high risk.
As populations in the developed world grow progressively more obese, lymphedema caused by obesity should therefore become more prevalent. For that matter, shouldn’t we already be seeing an epidemic of obesity-related lymphedema in the heaviest of nations?
A German study published this month appears to offer early evidence of this (ref. 4). The authors found that prescription of manual lymphatic drainage (a treatment for lymphedema) is increasing in Germany disproportionate to the burden of lymphedema, and instead correlates with a growing prevalence of obesity in that country.
As awareness of obesity-related lymphedema grows, along with interest and capacity to measure and track it, we are likely to discover that it is already very prevalent in our population.
Why would obesity cause lymphedema?
Lymphedema is the persistent accumulation of excess lymph fluid in a tissue or limb. Tissues of the body are continuously bathed in fluid, some of which returns to the heart via the venous system, while the remainder is collected by the lymphatic system. Any disruption of the lymphatic system should therefore cause an accumulation of fluid in the affected area. It is hypothesized that excess fat deposits in the legs might physically compress lymph vessels and thereby reduce lymph collection, much like pinching a drinking straw would prevent you from drinking. But this is not likely to be the whole story.
For obese individuals a combination of factors is likely at play. In addition to a physical compression of lymphatic vessels by fatty tissue, local inflammation caused by the presence of excess fat is hypothesized to further damage the vessels. To make matters worse, obese individuals are especially susceptible to overburdening their lymphatic systems to begin with, in particularly in the legs and feet where fluid is naturally prone to accumulate. This is due to the fact that excess fat increases the body’s production of lymph (so there is more to contend with in the first place), and can also promote venous insufficiency, a condition that in itself causes swelling.
If I reduce my BMI will my lymphedema go away?
The answer appears to be maybe. The 2015 study looked retroactively at patients who once had a BMI over 60 but who had since reduced their BMI to below 50. In this subpopulation some patients had lymphedema, while others did not, suggesting that perhaps a subpopulation could recover completely, but this data is far too weak and speculative to draw definitive conclusions.
To further explore the hypothesis that obesity-induced lymphedema could be irreversible the authors of this paper followed it up with a second very small qualitative study where they measured lymphatic function for one significantly overweight patient before and after weight loss surgery. The patient went from a very high BMI of 80 to a BMI of 36 18 months later, and no improvement in lymphatic function was observed by lymphoscintigraphy (ref. 5).
Considering the underlying physiology of the lymphatic system, it seems probable that lymphedema would subside only in those patients where the underlying lymphatic architecture has not (yet) been irreparably damaged. Given that lymphedema is typically both a chronic and progressively worsening condition, it is reasonable to expect that the sooner a patient can reduce their weight, the greater their chances will be of a full recovery. Unfortunately, if sufficient permanent damage to the lymphatic system has already taken place, life-long lymphedema management will be required.
I’m obese – now what?
Reduce your BMI
The accumulating evidence strongly suggests that patients with a BMI of over 30 are likely at an increased risk of lymphedema, particularly if they have preexisting lymphatic insufficiency that is currently asymptomatic, such as those who have undergone cancer treatment such as lymph node dissection, radiation, and chemotherapy.
All individuals should certainly attempt to keep their BMI below 50 (something that is advisable for a myriad of health reasons), or they will be at high risk of developing a potentially irreversible lower extremity lymphedema.
This is certainly not as easy as it sounds, and unfortunately, might in fact be more difficult than normal if your lymphatic drainage has already started to weaken. New research suggests that weakened lymphatic drainage promotes fat storage even before noticeable swelling is present. The study in question demonstrated that microenvironmental changes in adipose tissue caused by weakend lymphatic drainage actually discourages the tissue from converting fat into energy – both while at rest and in response to exercise. Since fat will in turn exacerbate #lymphedema, this finding reinforces the necessity of maintaining a healthy body weight.
Monitor for the symptoms of obesity-related lymphedema
Lymphedema caused by obesity usually occurs in the legs, and for perhaps three quarters of patients, both legs simultaneously.
At early stages of the condition swelling appears much like other forms of swelling. For example, you should be able to push on an area of swelling with your finger and make a small temporary indent (called the ‘pitting’ test). Swelling will also tend to be reduced or absent in the morning and worsen throughout the day. At later stages of the condition, tissue hardening occurs making the swelling feel denser and the limb feel heavier.
Lymphedema of the legs also typically includes the feet. To help you determine if your feet are swollen you can perform the ‘Stemmer’s sign’ test. Pinch and lift the skin on top of the foot in the area where your toes connect to your foot. If you are able to pinch and lift the skin, then you do not have fluid swelling or fibrosis in your feet and are therefore less likely to have lymphedema.
Unfortunately, the symptoms of lymphedema can be more difficult to identify in an obese individual due to larger limb size. These individuals may also suffer from other conditions that present with similar symptoms such as venous insufficiency or lipedema (see our patient guide to self-diagnosing lipedema), making accurate diagnosis more difficult.
If you are obese, in particular if you are approaching a BMI of 50, discuss lymphedema with your family doctor to make sure they are aware of your increased risk of developing this condition. Your family doctor may have little or no experience with lymphedema, and so you should not expect this condition to be top of mind for them.
If you suspect lymphedema, don’t wait to seek help
If you are overweight and are experiencing fluid swelling in your legs talk to your doctor about your symptoms and the possibility of lymphedema.
If lymphedema is suspected, seek professional help for reducing your bodyweight. Some degree of weight loss is critical in order to relieve the pressure on the lymph vessels and hopefully regain normal lymphatic function before irreversible damage is done. Even if your swelling has already become permanent, weight-loss will reduce your symptoms and help prevent further disease progression.
Individuals with suspected lymphedema should also seek out a specialist trained in Complex (or ‘Combined’) Decongestive Therapy (CDT), the international gold standard treatment for lymphedema.
A CDT therapist can help reduce the swelling and limb size through manual drainage techniques and compression garments, provide education on reducing the risk of infection and exercises specific to the lymphatic system, and offer guidance for ongoing self-monitoring and self-management of the condition.
While lymphedema awareness is growing, the link between bodyweight and lymphedema remains largely underappreciated. Consequently, overweight individuals who suspect they have lymphedema must be strong self-advocators and self-educators.
- Greene, A.K., et al. Lower-Extremity Lymphedema and Elevated Body-Mass Index. N Engl J Med. 2012; 366:2136-2137 article
- Helyer, L.K., et al. Obesity is a risk factor for developing postoperative lymphedema in breast cancer patients. Breast J. 2010 Jan-Feb; 16(1):48-54. abstract
- Greene, A.K., et al. Obesity-Induced Lymphedema: Clinical and Lymphoscintigraphic Features. Plast Reconstr Surg. 2015; Feb 20 Epub ahead of print. abstract
- Kroger, K., et al. Correlation between obesity and manual lymphatic drainage in Germany – a retrospective analysis from 2008 to 2016. Vasa. 2019 Dec 6:1-6 Epub ahead of print. abstract
- Greene, A.K., et al. Obesity-induced Lymphedema Nonreversible following Massive Weight Loss. Plast Reconstr Surg Glob Open. 2015 Jul8;3(6). abstract