Fat is Bad - But Not for the Reasons You Think

If you are surprised to learn that America is facing a fat epidemic, then you've been living under a rock. Why such an epidemic exists is both very, very simple and very complex. I won't be dealing with the complex reasons here - that is not the topic of this piece. Moreover it is by nature of its very complexity (touching on society, politics, economics, biochemistry, psychology and more) impossible to prove and thus only exists in the realm of speculation.

The very, very simple reason is that we eat too much. And/or don't exercise enough.

See? Simple. Very, very simple, even.

I will go into some of the rather complex science of weight gain and loss in a companion piece. The issue here is to discuss some of the not-so-obvious reasons why fat is bad. There are a lot. Enough for several posts, at least. We all know that being fat is the root cause of Type II Diabetes, complicates high blood pressure and high cholesterol and leads to heart attacks. But fat almost literally affects every system of the body and has profound impact on the practice of medicine apart from the health effects. Did you know about . . .

The Body Mass Index. More commonly known as the BMI. While not a perfect tool, the BMI is a surprisingly accurate predictor of weight related morbidity ("ill health"). We talk about folks with a BMI of 18-25 as normal, greater than 25 as being "overweight," over 30 as "obese" and over 40 as "morbidly obese." Some may be surprised to know that these numbers are not arbitrary.

If one plots all causes of morbidity against BMI one gets a rather "J" shaped curve. The broadest, flattest part of the base represents the least morbidity and corresponds to the 18-25 range. Below 18 the curve raises as we get into malnutrition and starvation territory. On the other side of the curve there is a series of inflection points at or around 25, 30 and 40, each steeper than the one before it. Not surprisingly the curve above 40 is the steepest on the graph. The higher your BMI the higher your chances of having serious health issues.

The moral of the story is that your BMI is directly related to your risk of all disease.

Ultrasound imaging. Ultrasound is a wonderful imaging modality. It requires a very low energy form with no known direct health consequences and is harmless to developing fetuses. It can take real-time moving images. It can easily show rates of blood flow in the vessels. And ultrasound devices are now about the size of a laptop computer, relatively cheap and don't require a lead-shielded room making them readily accessible to office providers or even traveling health care workers.

However, the problem with ultrasound is also that it is very low energy. Which means it has a limited ability to penetrate tissue. It can't see through bone at all, and even softer tissues attenuate it quickly. Tissues like fat. Ultrasound is of limited use on obese people. Two inches of adipose tissue and what's underneath it is essentially static.

So, what's the option? Either something more invasive, or relying on CT (a great tool, but involving exposure to radiation). I recently had a patient who weighed nearly 400 pounds and was suffering from heart failure (essentially caused by his weight). We needed to get an echocardiogram. But the TTE (TransThoracic Echocardiogram), where we "look" directly through the chest wall from the outside, which could give us the information we needed was not effective because of his size. The alternative? A TEE (TransEsophageal Echo), a procedure where the transducer is slid down the esophagus to look at the heart from behind. Obesity forced us to use a more invasive and dangerous procedure.

Palpation: One of the fundamentals of physical exam is actually feeling the patient. The doctor doesn't mash on your stomach for fun - she's trying to feel if there's something in there that there shouldn't be. A huge inflamed liver, maybe, or an aneurysm of the abdominal aorta. But on a obese person palpation is of limited use. Imagine feeling for your toes through a pillow versus a sock.

One of the least favorite aspect of the pelvic exam for women is the "bimanual exam" - one hand in the vagina, one on the abdomen. We feel for the dimensions of the uterus by pressing from side to center on the abdomen and feeling for motion on the cervix. This doesn't work well on obese women. We feel for the ovaries by stroking down the abdomen and trying to "catch" them between our two hands. It's tough even on thin women since a normal ovary is only about 2 cm in diameter. Nearly impossible on heavy women. What we hope to (never) find is a mass. I shudder to think how much larger an ovarian cancer would have to be for me to feel it in a 250 pound woman versus a 150 pound one. And care to take any guesses on the relationship between size of a tumor and the prognosis? It's not positive.

Childbirth: I recently completed ALSO - Advanced Lifesaving Skills for Obstetrics. We talked about shoulder dystocia, a potentially life threatening situation where the infants shoulders get stuck behind the pubic bone. One of the later maneuvers to try is to have the mother get on her hands and knees. (This has the potential to shift the infant and possibly dislodge it). But since shoulder dystocia occurs late in the labor process it is not unusual for a mother to be too physically exhausted to do this. So you have to find enough nurses or family members to hold her up. One of the instructors told a really scary story about what it took to get a 250 pound mother on her hands and knees. Four nurses. Nurses who had to be pulled away from their own laboring patients.

To make matters worse, obese women tend to gain more weight during pregnancy, which translates to larger babies. And big babies are the primary cause of shoulder dystocia.

I have also spoken with doctors and nurses who are convinced that obese women have more difficulty delivering. The best reason I've heard from this is that when obese women push there is too much tissue and it tend to dissipate the force of the push.

I've got more. And am collecting new ones all the time. I'll revisit this topic on a fairly regular basis to expand my list.

It's a Mad, Mad Medical Training World

Or, "What is a resident anyway?"

Medical training in the US is an odd mish-mash of formal education, tradition and state and federal regulation. Moreover, the US model of training is very different than the European model. And while there are a few countries that follow the US model, most other places in the world follow Europe.

In the USA, the progression of training is generally undergraduate, medical school, internship, and residency, followed by either practice or fellowship then practice. The undergraduate part is pretty straightforward - before being admitted to medical school you need to have completed some flavor of bachelor degree. The odd part is that it can be any flavor of bachelor degree. Certainly things like biology, biochemistry or pre-medicine are the most degrees, but any B will do. I have one classmate whose BS is geology. Another has a BFA (bachelor of fine arts). As long as you have all of the required classes (lots of biology, physics and chemistry), your piece of paper can say anything you want.

OK, so you get into medical school (congratulations!), and eventually you graduate. Congratulations (again), you're a doctor. That is, you have completed a doctorate level degree. And while you have more medical training than, say a PhD in philosophy, you have no more legal right to practice medicine than one. To do that you need to complete your internship. Indeed the first bit of confusion stems from this quirk of terminology. To wit: a physician is not synonymous with a doctor. "Doctor" is a degree, "Physician" is a profession. Technically being a doctor only connotes that one has completed a doctor level degree.

And this where history and modernity collide. Prior to the about the mid 60s all doctors (as in medical school graduates) had to complete an internship. The internship was one year of (usually) moth long rotations in a myriad of core medical fields like pediatrics and surgery. After completing internship a doctor was eligible for licensure in nearly every state, and could hang out their shingle as a "general practitioner" or GP. All those jovial, rumpled, small town docs in Norman Rockwell paintings took this route. My dad who is currently an ER doc took this route. If a doctor wanted to be a surgeon or a obstetrician he then needed to do a residency.

Residencies varied in length from two years for Internal Medicine to four for Surgery. It was also not at all unusual for a doctor to work for several years after his internship before beginning his residency. Not surprisingly, the locations for internships and residencies were very rarely the same.

Things gradually began to change in the years after WWII. Specialty medicine became much more common and the number of doctors completing residencies grew dramatically. It became common for doctors to go directly from internship to residency with no time for practice in between. Eventually specialty programs began offering "package" residencies - internship and residency in one location. At this point the distinction between internship and residency was essentially obliterated, although it still remains tradition to call first year residents "interns."

Today there are really no more GPs, in the sense that no one goes out to practice medicine after only one year of training. (Even the GP's modern replacements, primary care physicians, have specialty training, usually Family Medicine or Internal Medicine.) The intern year is still significant though. Even under the current "internshipless" system a doctor can not be licensed to practice until they've completed their first year of residency. An intern can only practice medicine under the direct supervision of a licensed doctor (kind of like driving with a learner's permit). At the end of their intern year residents must pass a board exam, after which they are eligible for licensure and able to practice without supervision.

There are a few residencies that do not automatically include the intern year. Many anesthesia programs do not, for example, requiring residents to complete a "transition" year (i.e. an internship) at another institution before beginning their residency.

Interestingly, the law regulating licensing has not changed. It would still be entirely legal for a doctor to complete her internship and then go out and start practicing medicine. No one does it, though. I suspect this has largely to do with getting malpractice insurance - I am sure it is prohibitively expensive (if it is available at all) for docs who have not completed a residency. I also strongly doubt there would be any health insurance companies willing to reimburse a GP. Savvy patients would be understandably reluctant to been seen by such a GP when more thoroughly trained physicians are everywhere. One would also not be eligible for board certification without completing a residency. In short, no more GPs.

And none of this address fellowship, board certification or restrictions on what a license does or does not allow you to do. But that's an essay for another time.