Underweight Can Be a Killer

"You can never be too rich or too thin" seems to be an adage adopted by American medicine. While there is no doubt that you can never have too much money to pay for American healthcare, it is in fact possible to weigh too little for good health. Here are some examples:

• Len had been a stand-out (American football) quarterback in high school, and had won a full athletic scholarship at a Big Twelve school. He was ripped, proud of his six-pack, and proud of his six percent  body fat. Just three weeks before he was to report to summer training before his freshman year, he suffered a freak accident. He tripped over his girlfriend's cat at the head of a staircase, fell to the bottom, broke his jaw, and fractured his neck. For a week in the hospital, Len only received intravenous fluids to stop dehydration. In just a week his body started to cannibalize muscle tissue, and in three weeks the gastrocnemius muscles of both legs were so badly deteriorated he could only walk with braces. His college football career never materialized.

• Susan also ate perfectly balanced, organic, wholesome meals. She was as thin at age 50 as she was at age 15, in fact, a little thinner. When she developed breast cancer and was given chemo, it was only three months before she developed cachexia, the wasting disorder. She survived cancer, but died of wasting because her body did not have the fat reserves she needed to survive weeks of not being able to eat.
• Throughout human history, periods of famine have been followed by periods of "pestilence and plague." Hungry people's immune systems become highly susceptible to infections, and when masses of people have survived starvation, infections tend to become epidemics.

When scientists reviewed 230 studies involving over 30,300,000 people that looked at the relationship between body mass index (BMI, a measure of weight taking height into account), they found a "U shaped" relationship between BMI and risk of death. It wasn't surprising that the risk of death of all causes in the morbidly obese (people who have a BMI greater than 45, which generally corresponds to weighing approximately 300 pounds or 140 kilos or more) was four and one-half times greater than the risk of death for people who had a BMI between 25 and 27, which corresponds to "normal" weight for height. It was surprising that the risk of death was 50 to 100 percent greater for people who had a BMI of 15 to 20, which corresponds to being 10 to 20 percent underweight or maybe a little more.

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Underweight was particularly predictive of mortality in people who had ever smoked cigarettes. However, in people who had been underweight for 20 years or more, there was almost no additional risk of death. The combined data of the 230 studies suggested that losing weight may be an early sign of a slow disease process, which causes weight loss years, perhaps 10 to 15 years, before it causes other symptoms.

What Kinds of Diseases Are More Common with Being Underweight?

When is being skinny a sign of being sick? Unintentional weight loss (losing weight without dieting) is a common sign of several conditions.

• The first symptom of severe, uncontrolled diabetes often is unexpected weight loss. The insulin resistance that leads up to diabetes is associated with weight gain, but when the insulin making cells in the pancreas are finally depleted by the disease, which may precede any obvious symptoms, then the body starts burning fat instead of sugar and getting rid of sugar by urination. People who have been pleasingly plump for many years can lose 10, 20, or even 30 percent of their body weight while eating ravenously, and only realize that they have diabetes when they become dehydrated and wind up in an emergency room.

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• The processes that lead to lung cancer seem to cause long-term weight loss even after people stop smoking. Smokers tend to be thinner than non-smokers even when they do not develop cancer. However, people who ever smoked who are destined to develop lung cancer tend to stay thin even after they quit and even if they seem to be eating too many calories for their activity levels.
• Both thin and normal-weight people are less likely to survive heart disease after stent procedures than the obese. Data analysis of twelve studies combined found that thin and normal weight people were up to twice as likely to die in the 30 days after a stent procedure, and up to 50 percent more likely to die in the first year after having stents placed in coronary arteries.

So does this mean that gaining weight could actually be a good idea? If you are thin because you simply don't have access to food, yes, you probably need to eat more. If you are losing weight without trying, especially if you are losing lots of weight without trying, you probably need to see a doctor to get testing for diabetes and your need to have appropriate cancer screening. However, for most people, the real question is whether you need to fight to lose weight just because you are a certain BMI. Always follow your doctor's guidance, but in general:

• If you are over 60, losing weight by dieting probably won't decrease your risk of deadly diseases. Losing weight may take stress off your joints and help you maintain your mobility, however. It's also helpful for most obese people over the age of 60 to get treatment for sleep apnea.
• If you are under 60, losing weight without dieting is usually a sign of disease. In particular, undiagnosed diabetes can be the reason for sudden weight loss without diet or exercise. 
• No matter what your age, eat for health. First make sure you are eating healthy meals with a minimum of saturated fat, preservatives, coloring agents, and sugar. Then eat to live, don't live to eat. Make a habit of deferred satisfaction with regard to eating. Get regular exercise. Let weight take care of itself unless your doctor tells you must lose weight.