Here’s the dilemma. Obesity raises your likelihood of contracting many serious diseases. However, once you have those diseases, obesity improves your chance of survival.
These are results that seem to rate a high five for obesity. If your weight is pushing up as you get older, are you ready to celebrate? The Snake Oil Willie Band seems to be, singing in this just-released video:
…I don’t look good naked anymore
I’m a deep-fried, double-wide version
of the man I was before.
Body Mass Index (BMI)
The evils of overweight have been widely publicized. The National Institutes of Health recite a scary list of weight-related health problems:
– Heart disease or stroke
– High blood pressure
– High cholesterol
– Gallbladder disease
– Some types of cancer
– Osteoarthritis (joint erosion)
– Sleep apnea (lack of oxygen during sleep)
Just how much extra weight is a problem? Most health professionals use a simple measure, the Body Mass Index or BMI, to measure overweight or obesity. It uses a formula that was invented in 1832 in an attempt to describe the standard proportions of the human build. Renamed the Body Mass Index, it was adopted as a good way to describe individual fatness.
Here is a typical interpretation of an individual’s BMI number:
BMI less than 15: very severely underweight
BMI from 15 to 16: severely underweight
BMI from 16 to 18.5: underweight
BMI from 18.5 to 25: normal healthy weight
BMI from 25 to 30: overweight
BMI from 30 to 35: moderately obese
BMI from 35 to 40: severely obese
BMI over 40: very severely obese.
Of course, we know that an individual cannot be represented by a number, or even a large group of numbers, so it’s not likely that a person’s health can be represented by a single number. Nevertheless, let’s follow this trail and see where it leads.
Your BMI is calculated from your weight (mass) and your height. I try to never give you an equation, but in this case an equation saves a lot of words:
You can also find your BMI from a chart like the following, which is credited to Wikipedia user InvictaHOG:
The solid lines mark BMI of 18.5, 25 and 30. The dashed lines in the colored sections mark BMI of 22.5, 27.5, 32.5, 35, 37.5 and 40. I’m not sure what BMI numbers are intended by the dashed lines in the white section.
Of course, you can simply look up your BMI in a table of numbers like this one.
What is Normal?
It’s been known that people who are seriously overweight are subject to more physical problems and die sooner. Since BMI is easy to measure, it became a convenient way to classify medical risk.
When researchers looked at mortality as a function of weight, they consistently found that among nonsmokers, the minimum risk of death occurs for a BMI between 20 and 25. (For current smokers the minimum occurs between 24 and 27.) Risk increases for people who are above this range, and also who are below this range. Data of this type led to the current designation of 18.5 to 25 as “normal weight.”
The Obesity Paradox
However, a mystery soon appeared. When specialists studied the treatment of people who had already been diagnosed with a serious disease, it turned out that “normal” weight is a liability. The patients who survive best are those classified as overweight, with a BMI between 25 and 30. This “obesity paradox” was first noted in coronary heart disease, and quickly observed many other cardiovascular conditions: hypertension (high blood pressure), acute myocardial infarction (heart attack), coronary artery blockage, heart failure, peripheral arterial disease and stroke. Researchers studying other chronic diseases took note, and soon an obesity paradox was found in other conditions as well: recovery from general surgery, type 2 diabetes, chronic obstructive pulmonary disease, kidney failure, osteoporosis and illnesses requiring intensive care. Additional studies show the obesity paradox in kidney cancer patients and in the ability to recover from severe infection.
The “obesity paradox” is generally agreed to be a real phenomenon. It is described in scholarly articles in, for example, Diabetes Care and the Journal of Sports Sciences. The paradox is also discussed in articles for the general public in the New York Times, Huffington Post, Detroit Free Press, HowStuffWorks and ScienceBasedMedicine.
A fascinating trio – OK, if you prefer, trifecta – of articles appeared in the August 2014 issue of Mayo Clinic Proceedings, in which the obesity paradox was successively confirmed, re-framed and perhaps explained:
– Confirmation. An article by Abhishek Sharma et al reviewed 36 studies involving more than 100,000 patients. The researchers confirmed that after treatment for coronary artery blockage, mortality is lower for overweight patients (BMI above 25) and higher for those who are underweight (BMI below 20). A BMI of 27.5 appeared to be best.
– Re-Framing. An article by Alban De Shutter et al looked at both BMI and Lean Mass Index (LMI) in a group of 47,866 heart disease patients. LMI is defined as BMI multiplied by the fraction of body weight due to everything except fat, that is, bone plus muscle plus water. The researchers found that although higher BMI led to lower mortality, it was because people with higher BMI also tend to have higher LMI. When the effects of body composition were considered, it was high LMI and not high BMI that seemed to protect the patients.
– Explanation. An accompanying editorial by Kamyar Kalantar-Zadeh et al proposes that the apparent benefit of overweight in surviving serious diseases may arise from increased skeletal muscle mass. Skeletal muscle is muscle that we can voluntarily control, as distinct from heart muscle and the smooth muscle found in blood vessel walls and elsewhere in the body. The article suggests that muscles may help us fight serious disease by producing myokines, which are biological molecules that support tissue regeneration and the immune system. The editorial hastens to add “The findings in these studies should not be considered as an attempt to undermine the legitimacy of the anti-obesity campaign in the best interest of public health.” In other words, restrain yourself from that extra trip to the buffet line!
Science Speculation: The relationship of obesity to health is a complex one that is just beginning to be unraveled.
In many ways, medicine is becoming more personalized. Just as DNA tests can predict susceptibility to certain diseases, eventually physicians who counsel their patients on weight will also take into account many details specific to the individual: their amount and location of body fat, their physical fitness, the chronic conditions that may affect them, and even their genetic makeup.
Since the day of uniquely personalized medical treatment has not arrived, here are some principles that are suggested by research results to date on obesity and disease:
Control Your Body Fat. If you have access to enough to eat and are not threatened with famine and starvation, you should try to minimize your body fat, especially fat around your midsection where the abdominal organs are located. But beware of garcinia cambogia and other quick-fixes supposedly endorsed by Dr. Oz. It’s your balance of “calories in” versus “calories burned” that really counts.
Build Your Muscle. Building muscle now will help you if and when you get seriously ill. Muscle mass helps you survive wasting diseases such as cancer, organ failure and serious infection, and also boosts your immune system.
Build Your Bones. Our genes predispose us to having heavier or lighter bones. However, bone mass can be increased and bones strengthened by weight-bearing exercise. Stronger bones decrease your chance of breaking your hip in a fall, an injury that often puts an older patient on a pathway to overall deterioration and premature death.
Strive for a Reasonable BMI. It’s easy to measure weight and height, and to calculate your Body Mass Index. If you are sedentary, keep your BMI in the range 20 to 25. Muscle weighs more than fat, so if you regularly exercise your muscles you can expect your BMI to increase, and it may go above 25. The more strongly you exercise, the higher your BMI can safely go, but keep it below 30 in any case.
Track Your Body Fat Percentage. This recommendation will probably be unpopular because it’s a nuisance. However, if you really care about your health, it’s not enough to read the scale. If your doctor can measure your body fat percentage, for example using ultrasound, that’s great but not very convenient for everyday monitoring. You can sacrifice accuracy but gain a lot of convenience if you use a skin fold caliper or even just measure your waistline. The most practical combination is to get a medical measurement of body fat percentage at your annual physical exam (you do have an annual physical, don’t you?), and then estimate changes between exams by skin fold or waist circumference.
Be a Proactive Patient. If you acquire a serious medical condition, ask a lot of questions. If your doctor wants you to lose weight, make sure that he or she is not giving you a cookie-cutter recommendation, but one that is tailored to your specific condition.
These suggestions can help you be the healthiest person you can be, until that glorious day arrives when medicine can tell us exactly what to do, to optimize our own individual health.
Are obesity and weight a concern for you? How do you manage both weight and fitness?
Acknowledgement: My thanks to Irving Cutter III for sharing with me the Snake Oil Willie Band video
Drawing Credit: tom, on openclipart.org