There's no doubt about it: The majority of people with heart disease are overweight. They may not be grotesquely overweight, just a few pounds over. But weight plays a crucial role in activating numerous factors that heighten risk for heart disease.
Excess weight reduces HDL cholesterol, raises triglycerides, increases small LDL (enormously), fans the fires of inflammatory responses (CRP, IL-6, TNF-alpha, etc.) raises blood pressure, increases resistance to insulin and raises blood sugar. Overweight people tend to be less physically active, may develop diseases of obesity like sleep apnea, and on and on. You've heard this all before.
But why do slender people develop heart disease? If we can't blame weight, what is to blame? By slender, I mean body mass index (BMI) of <25. (Yes, I know there are other ways, better ways, to gauge healthy weight. But, for simplicity, I'll use BMI.) Let's put aside the two obvious causes of heart disease, cigarette smoking and Type I diabetes. (I'd be shocked if any cigarette smokers read this blog.)
Slender people develop heart disease because:
1) They have lipoprotein(a)--The big, big neglected risk factor. In fact, the Lp(a) genotype is, in my casual observation, associated with a slender phenotype (genotypic expression). The prototypical example that makes headlines is the marathon runner--slender and superbly fit, but develops heart disease anyway. People wax on about the uncertainties of exercise and fitness when they hear about Jim Fixx and Alberto Salazar. But one factor would explain it all: Lp(a).
2) The murky category of the normal weight obesity . These people are generally recognizable by their flaccid tummies despite falling into a favorable BMI <25. Small LDL is the standout red flag in these people.
3) They were previously overweight but lost it.
4) They were former smokers.
5) Vitamin D deficiency--Deficiency of vitamin D is important for everyone's health. But there appears to be some people for whom it is the dominant risk. I believe that one of our great Track Your Plaque success stories, Neal, falls into this group. Some people who are vitamin D deficient develop colon cancer, others develop diabetes, others develop osteoporosis or multiple sclerosis, while others develop coronary heart disease and plaque. The likely reason for the varied expression is variation in vitamin D receptor genotypes (VDR genotypes).
6) The murkiest of all: Hypertension genotypic variants. This is a poorly sorted-out category, and one principally based on my observations along with scattered observations in such things as variations in the angiotensin converting enzyme genotypes. But I am convinced that there is a small percentage of slender people who show variation in some genetic type that predisposes to hypertension and heart disease. They also show a propensity towards enlargement of the thoracic aorta. This group is also among the most difficult to control in the Track Your Plaque approach, i.e., they have difficulty slowing or stopping the growth of heart scan scores. While blood pressure control in this group is important, it does not seem to remove the excess source of risk.
So, yes, being slender does put you into a lower risk for heart disease category. But it does not mean you are immune.
You can also be an overweight person who still harbors some of the features of the slender--you're an overweight slender person. The above list can still therefore apply.