3 Things a Tape Measure Tells You

If you want to know about your heart health, what do you use as a reference point?

Maybe you go by how you feel when you climb a long flight of stairs or run for the bus. Things like that are a sensible example of heart health expressed in functional abilities.  What about your weight?  In many cases that does give a good clue to heart health, but there are people who are overweight but fit, and people with a “normal” weight who are metabolically unhealthy.  Many people focus on their LDL-cholesterol.

Here’s a simple tool you should check out: a tape measure.

Research now shows that different types of LDL-cholesterol don’t all pose the same heart risk.  LDL (low-density lipoproteins) come in different sizes.  Big ones, it turns out, don’t do nearly as much damage as the small dense LDL (sdLDL).  These sdLDL can more easily get into blood vessel walls to promote development of the plaque that defines atherosclerosis.  These small LDL are not cleared from the blood as easily as larger LDL, so they are available longer to unload their cholesterol load.  And the cholesterol they carry is more easily oxidized, which is the form that does most damage to our blood vessels.

Blood tests beyond the standard tests most doctors use are needed to test for sdLDL.  That’s where a tape measure comes in.  Increased levels of sdLDL tend to occur along with other metabolic changes that together are referred to as “Atherogenic Dyslipidemia”. It includes elevated levels of insulin and blood triglycerides and low levels of HDL (“good” cholesterol).

Tape Measure Message #1: Coronary arteries, beyond LDL

Using coronary angiography, researchers found that elevation in two factors doubled the risk of finding at least one coronary artery with at least 50 percent narrowing.  This narrowing was strongly related to what they call the “hypertriglyceridemic waist”.  Metabolic syndrome, a constellation of abnormalities, has long been linked to at least a doubling of heart disease risk.  These researchers found, however, that this blood vessel narrowing could be identified just about as well by the combination of two factors: blood triglycerides and waist size.

With that link to narrowed arteries measured by angiography, you’d probably assume that this “hypertriglyceridemic waist” was also linked to LDL cholesterol, right? But it wasn’t.  Total LDL was no different among groups with or without this two-factor elevation, nor was it different among groups who did or did not meet the full criteria for metabolic syndrome.

However, the women with increased waist plus elevated triglycerides were more likely to show the constellation of disordered lipids referred to above:   besides having higher triglycerides, they also tended to have lower HDL (“good”) cholesterol levels. And even though their LDL itself was not higher, they had more of the small dense LDL that pose greatest risk.

Tape Measure Messages #2 and #3: Looking beyond the heart

Women with “hypertriglyceridemic waist” showed the metabolic abnormalities that often go along with this lipid pattern. Insulin is a hormone that goes up after you eat to help convert food into fuel, and then levels go back down.  For women with elevated triglycerides and waist, the fasting levels of insulin in their blood were higher, and a measure of insulin resistance was also higher.

Insulin resistance occurs when the body doesn’t respond to insulin normally, so higher and higher amounts get pumped out to keep blood sugar under control. Insulin resistance is often the driving force behind lipid changes like elevated triglycerides and low HDL.  But it raises another red flag:  insulin resistance is also how type 2 diabetes begins.  The “hypertriglyceridemic waist” women did include more women who already had known diabetes, but that was only about a third of the women.

That means that not only were these women – identified by elevated triglycerides and increased waist size – more likely to have at least 50 percent narrowing of one or more coronary arteries, they also showed in their signs that they were more likely to develop diabetes.

Research in the field of cancer now suggests that this metabolic environment with high insulin, often accompanied by chronic low-grade inflammation, may be fertile ground for development of some types of cancer. In fact, increases in waist size are directly linked to increase in risk of colon cancer.

Not Just a “Woman Thing”

This particular study with angiography of coronary arteries involved only women, and some research does suggest that women’s heart health may be especially affected by this constellation of lipid abnormalities. However, increased waist plus elevated triglycerides clearly raises a red flag in men, too.  In a large population study known as EPIC, men with this profile had more than double the risk of developing heart disease over 9.8 years.  Women were even more strongly affected, with almost four times the heart disease risk as women who did not have this dual elevation.

Another research team, focused on the abnormalities likely to accompany waist and triglyceride elevations – elevated fasting insulin, increased levels of small dense LDL and increased levels of a protein called apo-B that goes with LDL.  They found that compared to men who had normal levels for at least two out of these three factors, men with all three elevated  were more than five times as likely to have a heart attack or other heart “event” that characterizes atherosclerotic heart disease.

What’s Your Number?

You may be used to hearing healthy waist limits cited as 40 inches in men and 35 inches in women.  But these are waist sizes associated with obesity, and risks associated with insulin resistance begin at lower levels of abdominal fat. The researchers doing the work discussed here used waist sizes equivalent to 36 inches in men and 34 inches in women as the cut-off points.

Research is still underway on this subject, trying to identify waist sizes that are most helpful to identify people that might be at risk and missed by other screening tests, without tagging so  many people that “high” loses its meaning.  Representatives of organizations involved in research on heart disease, diabetes and metabolic syndrome convened, and their temporary agreement was to use the equivalent of 37.5 inches in men and 32 inches in women.

Asian men were identified as exceptions to this guideline, with a cut-off of 36 inches, or possibly even 34 inches for men of Japanese ancestry.  If waist size is going to be regarded as an important screening tool, more research is needed to define standards for people of different ethnicities, because genetics does influence patterns of body fat distribution, which is what waist size is assessing.

What to Do About Your Number?

Since insulin resistance seems to be a driving force behind the metabolic abnormalities and health risks tied to increased waist, look at strategies in light of that as a goal.

#1:  Go for a walk.  Physical activity directly reduces insulin resistance and insulin levels.  The effect lasts for 24 to 72 hours, so experts advise 30 minutes of moderate exercise daily or 60 minutes every other day.  Don’t let more than two days go by without moving.  Researchers are looking at how timing of a walk may affect results, and we’ll come back to that in the future.

#2 Break up your sitting time.  As you heard in my video interview with researcher Barry Braun, an expert on exercise and its metabolic effects, even if you get recommended amounts of physical activity, too much extended sitting poses problems. If you sit for long periods of time because of work, travel or lots of time in front of a computer or TV screen, getting up and moving for just a few minutes every hour or so seems to actually make a difference to body metabolism. You’ll find more details about these findings and some ideas about what you can do in my Smart Bytes® blog post, Extended Sitting: Why researchers see health impact & What you can do.

#3 Cut a few hundred calories. To begin to burn off the extra fat around your waist you need to burn up more than you consume.  Research shows that for most people, it’s hard to lose body fat only by exercise; they need to make some sort of eating change, too.  For now at least, don’t try to revamp your whole eating pattern.  Make one or two simple changes that you can put in place today.

It’s body fat you want to reduce, but don’t assume that means eating less fat is the answer.  Fat is a concentrated source of calories, so for some people, switching to lower fat options or adding less fat is a great strategy.  However, people with this metabolic combination of elevated triglycerides and insulin may be especially sensitive to too much carbohydrate.  These are the people for whom switching from chips to pretzels, or ice cream to fat-free ice cream, for example, may not bring desired metabolic changes.  Instead, cut the sugar-sweetened drinks, enormous glasses of juice, or all-you-can-eat pasta bowls.  We’re not talking about giving up carbohydrates; but check for places you might be going overboard on refined grains or high-sugar foods as a good place to start cutting some calories.

Let’s talk:  What simple small changes have you made – or are you considering – that could cut about 100 calories without leaving you feeling deprived or hungry? Have you seen some good lists in magazines or websites? Please share!

Resources: 

For more about Metabolic Syndrome, check this research update.

References

LeBlanc S, Coulombe F, Bertrand OF, et al. Hypertriglyceridemic Waist: A Simple Marker of High-Risk Atherosclerosis Features Associated With Excess Visceral Adiposity/Ectopic Fat. J Am Heart Assoc. 2018 Apr 13;7(8):e008139.

Neeland IJ, Ross R, Després JP, et al. Visceral and ectopic fat, atherosclerosis, and cardiometabolic disease: a position statement. Lancet Diabetes Endocrinol. 2019 Sep;7(9):715-725.

Blackburn P et al. Hypertriglyceridemic waist: a simple clinical phenotype associated with coronary artery disease in women. Metabolism. 2012;61(1):56-64.

Arsenault BJ et al. The hypertriglyceridemic-waist phenotype and the risk of coronary artery disease: results from the EPIC-Norfolk prospective population study. CMAJ. 2010;182(13):1427-1432.

Alberti KG et al. Harmonizing the metabolic syndrome: a joint interim statement of the International Diabetes Federation Task Force on Epidemiology and Prevention; National Heart, Lung, and Blood Institute; American Heart Association; World Heart Federation; International Atherosclerosis Society; and International Association for the Study of Obesity. Circulation. 2009;120(16):1640-1645.