Research Reviews

Research review: Can your belt predict your fate?

by Helen Kollias

Forget palm reading, horoscopes and crystal balls. If you really want to know what’s going to happen to you, check your closet. Your belt may hold your destiny… and if that belt is too big, the “tall, dark, handsome stranger” predicted might just be your cardiologist.

It’s time to confess: At PN we’re fattists. We believe that when it comes to health, all fat isn’t created equal.

What? Isn’t fat, well fat?

Nope. Just like real estate, it’s all about location. Two people who are equally overweight, with the same percentage of bodyfat, can have different risks of disease and early death if their bodyfat distribution patterns are different.

Apples vs pears

You may have heard of fruit-based descriptions of body shape — apple shaped versus pear shaped.  These fruits are used to describe bodyfat distribution.

Apple shaped individuals carry most of their fat around their middle (abdominal fat), while the pears carry most of their fat around their hips and legs (gluteofemoral fat).

Apples are sometimes known as android, meaning male-type, since most men tend to be shaped this way. Pears are sometimes known as gynoid, or female-type, since most women tend to be shaped this way.

If you’ve got a “spare tire” or a “beer belly” on top of relatively lean legs, you’re an apple. If you’ve ever been described as “bootylicious” or “an hourglass with most of the sand at the bottom”, then you’re a pear.

It turns out that you while can’t compare apples to oranges, you can compare apples to pears.

And being a pear is better, because apples have higher risk of disease and premature death than pears. So in terms of health, abdominal fat (apple) is worse for you than gluteofemoral fat (pear).

Visceral vs subcutaneous fat

Actually, there is a little more to the importance of abdominal fat.

You see, abdominal fat includes subcutaneous fat and visceral fat. Subcutaneous fat is the fat you can pinch; it’s the stuff that sits just under your skin. Abdominal subcutaneous fat is what stands between you and your six-pack (and what is taken out with liposuction).

Visceral fat sits deep in your abdominal cavity around your internal organs (aka the viscera). Visceral fat is more important than subcutaneous fat in determining overall health.

In small amounts visceral fat is good. It pads and cushions your organs like oily bubble wrap so that when you jump, fall or change direction quickly your kidneys or liver don’t smash into your vertebrae or ribs, causing damage. But in large amounts, visceral fat is a problem.

Too much visceral fat has been linked to things like systemic inflammation, high blood pressure, cardiovascular disease and type 2 diabetes.  Visceral fat increases as we age, which is why many types of bodyfat calculations take our age into account.

In general, although overfat pears do have some visceral fat, overfat apples tend to have a lot more.

(Interestingly, despite being overweight, sumo wrestlers don’t have much visceral fat and subsequently are in good health – that is until they retire.1 It’s believed that their physical activity protects them from accumulating visceral fat.)

Even though it has been established that visceral fat is key to accessing risk, current health guidelines are mostly based on body mass index (BMI), which doesn’t necessarily reflect visceral fat or fat at all.

Note: BMI = weight (kg) / [height (cm)]2.

Table 1 – BMI and Weight Classifications 2

BMI Classification
18.5 or less Underweight
18.5 – 24.9 Normal
25.0 – 29.9 Overweight
30.0 – 39.9 Obese
40 or greater Extremely obese

bmi chart Research review: Can your belt predict your fate?

While BMI does identify individuals who are over-weight, it has a few problems.

  1. BMI doesn’t distinguish between fat and muscle. Many muscular athletes and bodybuilders may fall into the “overweight” or “obese” category.
  2. BMI doesn’t account for fat distribution. And as you’ve seen earlier, fat distribution is key to determining risks of disease.

Table 2 – Classification of Overweight and Obesity by BMI, Waist Circumference, and Associated Disease Risks3

Disease Risk* Relative to Normal Weight and Waist Circumference
Waist Circumference
BMI Men <102 cm (40 in)
Women <88 cm (35 in)
Men > 102 cm (40 in)
Women > 88 cm (35 in)
Underweight < 18.5 - -
Normal 18.5 – 24.9 - -
Overweight 25.0 – 29.9 Increased High
Obesity 30.0 – 34.9 High Very high
35.0 – 39.9 Very high Very high
Extreme obesity 40.0 + Extremely high Extremely high

*Disease risk for type 2 diabetes, hypertension, and cardiovascular disease.  (Increased waist circumference can also be a marker for increased risk even in persons of normal weight).

Today’s research review article asks whether waist girth and hip to waist ratios are better indicators of risk of death.

Pischon T, et al. General and abdominal adiposity and risk of death in Europe. N Engl J Med. 2008 Nov 13;359(20):2105-20.

Methods

359,387 participants were measured throughout Europe. Measurements included height, weight, waist girth and hip girth. Participants were excluded if they had a previous history of cancer, heart disease or stroke.

The average age of participants was 51.5 years old +/- 10.4 years.

Waist girth was measured either at the narrowest circumference of the torso or the mid-point between the lower ribs and iliac crest.

Hip girth was measured horizontally at the largest part of the hip or over the buttocks.

Follow-up occurred after an average of 9.7 years and in that time there were a total of 4,723 deaths in the group.

Obesity was defined a bit differently than the National Heart Blood and Lung Institute. In this case, obesity meant:

  • having a BMI over 25 (up to 34.9)
  • a waist girth >102 cm (40″) for men and >88 cm (35″) for women
  • a waist to hip ratio >1.0 (men) and >0.85 (women)

Results

BMI, waist and hip girths

First, BMI was very strongly correlated to waist circumference (Pearson partial correlation coefficient = 0.85 (men) & 0.84 (women)). And BMI was correlated to waist-hip ratio though not as strongly (Pearson partial correlation coefficient = 0.55 (men) & 0.38 (women)).

In other words, if your waist is big, particularly if it’s big relative to your hips, you probably have a higher BMI too. Not much of a surprise there.

But here is something more unexpected: BMI and risk of death is not linear: as your BMI goes up your risk of premature death does not necessarily go up with it. BMI actually had a “J-shaped” relationship to the risk of premature death.

This means that people with the lowest risk of death were in the middle: men with a BMI of 25.3 and women with a BMI of 24.3. People with BMIs higher or lower had higher risks of death.

That’s right — people with low BMIs had increased risk of death compared to those with slightly higher BMIs.

Larger waist girth and hip-to-waist ratio was also associated with increased risk of death. But it turns out that these were more accurate predictors in smaller people.

Waist girth and hip:waist ratio in individuals with a BMI of less than 27.7 in men or less than 26.6 in women was a much better risk indicator than those with BMI greater than 27.7 (or 26.6 as the case may be).

What does that mean?

  • If you have a BMI of less than 27.7 (or 26.6) or are relatively smaller, then go with your waist girth or a waist to hip ratio to figure out if you are in trouble.
  • If your BMI is greater than 27.7 (or 26.6) you need to lose weight (assuming you aren’t bodybuilding).
  • With a high BMI – waist girth and waist to hip ratios were NOT very good at assessing increased risk of death. So with a high BMI (>27.7 in men or >26.6 in women) you are still at great risk, but waist girth and waist:hip ratios don’t do any more to explain or predict your risk.

Skinny-fat

What’s going on with the lower BMI people? Well, the low BMI people are the skinny-fat people of the world.

Yup, these people have little to no muscle. Thus they can have relatively low BMI values (if you consider 27.7 low), but they actually have a high bodyfat percentage.

Interestingly, these skinny-fat people were more likely to be smokers and have higher waist girths and higher waist:hip ratios. The authors think that smoking may change fat distribution and cause more visceral fat deposits.

Yes! If you didn’t think smoking was bad enough it may be causing your beer belly –- though I’m sure beer is not completely innocent.

“Adjustment for BMI”

For a given BMI in both men and women, risk of premature death increased as waist size increased. For every 5 cm (2″) increase in their waist girth, their chance of death increased by a factor of 1.17 (for men) or 1.13 (for women).

For example, if we take two men who are the same height and weight, but Guy #1 has a waist 5 cm larger than Guy #2, then Guy #1 is 1.17 times more likely to shuffle off this mortal coil a little earlier.

The same holds true with the waist:hip ratio. For a given BMI every 0.1 increase in ratio there was a 1.34 increase in risk in men and 1.24 increase in risk in women.

Obviously, there is a point where if your waist girth is very small that’s not good either.  But, in this group the lowest measurement for waist girth was 60 cm (about 24”) – slim but not shockingly thin.

Waist and hip measures

So why don’t health care professionals use waist and hip measurements more often? I’ve never had my waist or hip measurements taken at the doctor’s office. One bizarre explanation suggested by the authors was that it’s too hard to take waist and hip measurements accurately. Ummm… Don’t doctors go to medical school for 4 or 5 years and then do years of residency? Don’t they learn to do things that are much more complicated than measuring waist and hip girths -– like, uh, surgery? If I can’t trust my doctor to measure my waist then I think I should be really worried.

The more likely explanation is that there just aren’t enough data yet to have a clear understanding of what’s “normal”, and the doctors haven’t been trained to take the measures in a standardized way.

Conclusion

People with lower BMIs or lower bodyfat should pay more attention to waist girth and waist to hip ratios.

People with higher BMIs (>27.7 for men or >26.6 for women) who are not bodybuilders should focus on fat loss regardless of waist girth and waist to hip ratios.

Most of us shouldn’t rely too much on our scales but on the measuring tape or more conveniently, on how our clothes and belts fit.

References

Click here to view the information sources referenced in this article.

Learn more

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