Paradoxes in medicine: What do they really mean?

When studies have unexpected results, I feel the need to investigate further.
In life we run into paradoxes all the time. A paradox is defined as a statement or opinion that seems to contradict itself. For instance, “You should not go near the water until you learn to swim” is a paradox. You can’t learn to swim until you get in the water.

There are two recent apparent medical contradictions, both obesity paradoxes. One refers to heart attacks and the other to type 2 diabetes.

Obesity paradox in heart attacks

A newly published meta-analysis involving two studies finds that obese patient are more likely to survive a heart attack at year one than are patients who have a normal body mass index, known as BMI (Am J Med. 2012 Aug;125(8):796-803).

In other words, the results show that a patient’s risk of mortality from a heart attack is inversely related to weight. Those who were obese had the lowest mortality rate from a heart attack: 4.7 percent. Those who were overweight had a 6.1 percent mortality rate, and those with normal weight had a 9.2 percent mortality rate. This is a paradox. It’s logical to assume the higher the weight the higher the risk of mortality, but that isn’t the case.

Although the reasons were unknown, the authors surmise that this effect may occur because obese and overweight patients seek medical attention with their symptoms earlier than normal weight patients. Overweight and obese patients may have a heighten awareness of their heart attack risk.

So what do we do about the paradox? At face value the study would seem to imply that it is better to be obese, because your prognosis may be better after suffering a heart attack. However, if you look below the surface, it is a more complex issue. Obese patients may be at higher risk for all-cause mortality and
cardiovascular disease.

Obesity’s impact on all-cause mortality

Obesity was found to increase the risk of all-cause mortality. This was demonstrated in a very large observational study, The Nurses’ Health Study, which showed a linear relationship with risk. Patients who were overweight had a 30 to 60 percent increased chance of all-cause mortality, while obese patients had over a 200 percent increased risk of death (N Engl J Med. 1995;333(11):677). Also, gaining 22 pounds or more after age 18 resulted in increased risk of all-cause mortality in middle age.

Obesity and cardiovascular risk

Obesity seems to be an independent risk for heart disease beyond high blood pressure, high cholesterol and type 2 diabetes, according to the American Heart Association (Circulation. 2006;113(6):898).

The Framingham Heart Study, a large observational study, showed a statistically significant increased risk for cardiovascular disease in both overweight and obese patients, with some patients followed for as long as 44 years (Arch Intern Med. 2002;162(16):1867). Those who were obese had the highest risk, with a 46 percent increase in men and 64 percent increase risk in women.

Obesity and fatal heart attacks

In an observational study following men over approximately 15 years, obesity in middle-aged men significantly increased their risk of death from heart attacks (Heart 2011;97:564-568). Interestingly, this study, just like the obesity paradox study, controlled for other risk factors, and even with these taken into account, the men had a 60 percent greater risk of dying from a heart attack. The authors suggest the reason is that inflammation underlies obesity’s effects.

The obesity paradox in type 2 diabetes

There were counterintuitive results in a recent meta-analysis, involving a group of five studies, with participants who became type 2 diabetes patients during the study (JAMA. 2012;308:581-590). The patients who were normal weight were two times more likely to see an increase in total mortality compared to patients who were obese. There was no significance difference in cardiovascular mortality.

The authors could not explain why there was a higher mortality in normal weight patients except to hypothesize that it may have to do with inflammation, pancreatic beta cell functioning and/or the extent of plaque development in the arteries. However, only 11 percent of patients who had type 2 diabetes were of normal weight, whereas 89 percent were overweight or obese.

It is interesting because more than 80 percent of cases of type 2 diabetes are associated with obesity (www.uptodate.com). Some in the medical field have taken to calling the phenomenon “diabesity.” This study reinforces that notion. Even though the normal weight patients had a higher mortality rate, the overall risk of developing type 2 diabetes was much higher in obese patients.

In the accompanying editorial to the diabetes study, the author refers to diabetes patients of normal weight as MONW (that is, metabolically obese normal weight) individuals (JAMA. 2012;308(6):619-620).These are obviously not healthy patients, despite their BMIs being in the normal range. The author recommends healthy weight loss — an alteration in body composition so that there is a loss of fat mass and an increase in lean body mass. This, she suggests, can occur with a Mediterranean-type diet and exercise.

The caveat with normal weight

Normal weight does not necessarily equal health. It is a paradigm that is long overdue for a shift. I hear people say all the time that this person is thin, so he or she must be healthy, and we know that is not necessarily true.

Chronic diseases occur in patients of all different BMIs — cancers, heart disease, autoimmune diseases and even diabetes — although weight may exacerbate or increase risk. The scary part is that almost one quarter of patients in the U.S. are metabolically abnormal, according to the Third National Health and Nutrition Examination Survey (Arch Intern Med. 2008;168(15):1617-1624).

The moral of the story is that it’s important to read between the lines in some studies. Whatever you do, know that there are many complications that are associated with obesity.

Just because there may be an apparent benefit to obesity, there are more downsides. Thin or normal weight does not imply fit or lean body mass. Monitoring body composition changes in combination with a healthy lifestyle is the best defense against getting caught up in the aforementioned paradoxes.

Dr. Dunaief is a speaker, author and local lifestyle medicine physician focusing on the integration of medicine, nutrition, fitness and stress management. For further information, go to the website www.medicalcompassmd.com and/or consult your personal physician.