Can skinny be fat?

You're going to hate this.

Dr. Romero-Corral and colleagues from the Mayo Clinic presented an analysis of the National Institutes of Health-funded National Health and Nutrition Examination Survey (NHANES-3) at the recent American College of Cardiology meetings. (Science Daily also has some coverage on this report.)

Their analysis identified 2127 adults from the NHANES database who had normal body-mass indexes (BMI) between 18.5 and 24.9 units), average age 41 years old. When broken down by percent body fat (measured with bioimpedance, meaning a small electrical current is passed through the body, much like what the store-bought Tanita devices do), with normal-weight obesity defined as >20% body fat in males, >30% body fat in females, 55% of participants met criteria for designation as normal-weight obesity.

Compared to people with similar BMI's but who fell below these body fat percentage cut-offs, the normal-weight obese men had increased ratios of Apo B to Apo A1; were much more likely to have increased blood sugars or be diabetic; have higher C-reactive protein (CRP); were several-fold more likely to meet other criteria for diagnosis of metabolic syndrome; had lower HDL cholesterols; and had higher blood pressure. Women with normal-weight obesity were four-fold more likely to have coronary disease.

While preliminary, this suggests that a substantial number of people with apparently favorable body weights and BMIs are, in actuality, overweight when judged by metabolic parameters. This then probably leads to increased risk for heart disease. We can then fairly readily extrapolate the argument that a reduction in weight to even lower BMIs likely reduces or corrects these patterns.

This argument is similar to that proposed by several others, arguing that BMI is a flawed measure, since it does not incorporate muscle mass or skeletal factors ("big- or small-boned"). Instead, they have argued that waist circumference is preferable.

The normal-weight obesity syndrome was originally identified by Dr. Antonio de Lorenzo and colleagues at the University of Tor Vergata, Rome, Italy, and reported in Normal weight obese (NWO) women: an evaluation of a candidate new syndrome. Their studies of women with this "syndrome" have suggested that heightened measures of inflammation are present despite apparently normal body weight and BMIs. One such report, Normal-weight obese syndrome: early inflammation?, is available in full-text.

Is there a lesson to be learned for the Track Your Plaque program? I believe there is. I believe it means that, if you have any weight-sensitive parameter, such as low HDL, small LDL, high triglycerides, high CRP, high blood sugar, high blood pressure, etc., then further weight loss might be considered, even if BMI is around 25. Obviously, there is a rational limit to how far you can push this concept. (Anorexia is not good for you either.)

I find this a useful concept. It provides yet another potential strategy to pursue when the above patterns are encountered. Perhaps it's also a way to cap reliance on niacin, whose effects closely mimic that of weight loss.

Now that's a lot more preferable to more and more statin drug, isn't it?

Copyright 2008 William Davis, MD

Comments (6) -

  • Anna

    4/29/2008 5:42:00 AM |

    Very interesting.  I've been paying attention to this issue as the reports have come out the last few weeks.  As a mid-40s female with a BMI hovering around 22 (5'3.5", 125 #), despite losing about 20# 4 years ago with a LC diet, I know I am still carrying more fat on me (and in different places) than I did 15 years ago at about the same weight.  

    What about strength training to build muscle mass  and drop body fat % instead of losing weight?   I don't really want to lose any more weight and I think I have hit the limit of weight loss from carb restriction.  I don't like to restrict calories, nor do I think it is effective for me.

    I've never liked exercise for the sake of exercise, but I think it was those incredibly boring cardio routines that put me off gyms and exercise routines (plus I found it was much easier to lose and maintain weight through carb restriction than through exercise).  

    But I've been reading up on the "slow strength" routines and they seem like a very efficient way to enhance my metabolism and muscle/fat ratios, especially since my glucose metabolism is already impaired.

  • Richard A.

    4/29/2008 2:00:00 PM |

    Maybe another approach for the normal weight obese is to take up weight lifting.

  • Anonymous

    4/29/2008 3:07:00 PM |

    My brother in law liked this post.  He is a former rugby player, 6 foot, 200 plus lbs. in size.  He looks like he is chiseled out of granite with the muscles he has.  I doubt there is more than 10% body fat on him, but he tells me that for years he has been considered obese by the BMI.

  • Zute

    4/29/2008 3:46:00 PM |

    I'm curious why the association it seems most medical people leap to is that it is the obesity causing the issue rather than the obesity being yet another symptom.

    Strangely if you cut out the refined carbs, grains, sugars, excess starches, all the symptoms correct themselves.  Sure, you can do the same thing with calorie restriction but we should know from Keyes starvation experiment that that doesn't really work long term with a high carb diet.

    Is there any real evidence it is the fat causing metabolic syndrome versus the metabolic syndrome causing the fat?

  • Anonymous

    4/30/2008 3:50:00 PM |

    This article pretty much describes me.  5'8" male, about 165lbs and a BMI of 25.  I've always had a problem gaining muscle so although I look normal my body fat was about 23% and I had high triglycerides.  I bought a bowflex and have worked hard to gain some muscle.  I'm now about 21% body fat and there is some muscle gain.  I don't know if I'll ever make it to 15% body fat, but I'm trying.  BMI is pretty much a joke.

  • Anonymous

    5/1/2008 3:03:00 PM |

    BMI is a fairly crude measure.  For the majority it probably has some value.  As others have pointed out it can incorrectly identify some heavily muscled people as overweight whilst suggesting some overweight people aren't overweight.  Perhaps a better indicator of obesity is waist measurement, or the waist to hip ratio.  In particular It doesn't appear to be healthy to carry significant amounts of weight around the middle.  

    Looking at old black and white films or photographs of crowd scenes, its noticeable that most people are lean: much more so than today.  I have been struck by how lean, and healthy, many soldiers look in what must have been harrowing and stressful times.  Maybe it was the more active lifestyle and spartan lifestyles.

    I doubt you could look at many modern day crod secenes and be impressed by how lean and healthy the people looked.  Even the London marathon contained quite a high proportion of overweight participants!