• Obesity & Overweight
  • How does a person end up with too much body fat?
  • What are the consequences?
  • How can fat be lost?
  • Why is it so difficult?

Obesity has a more specific meaning in medicine than"just being fat". There is a line drawn in "fatness" over which a person is "obese" and under which he's overweight, but not obese. This article includes both labels in the title for a reason.

• That line between overweight and obese has to do with making more accurate calculation of the risks of diabetes, heart disease, and other health impairments for a particular perosn.
  • Important as that is, this line has no critical significance when it comes to understanding the nature of being too fat.
  • What's true for the very overweight is true for the obese, and - in the United States today - that means most adults, because something ike 60 % of American adults are one or the other.
• Further- the charts are guidelines and not exact assessments for each individual. A handful (or cubic centimeter, any given volume) of fat weighs much less than the same one of muscle, or of bone:
  • The 5 foot tall woman (with size 9-wide feet ) who holds a world record for power-lifting is not "fat" at all, and yet weighs 5 pounds more than the 5 foot tall woman (with size 4-narrow feet ) whose biceps can't be felt even when she fully flexes.
  • The first woman may have little to no extra body fat and, the second woman, dumpling-like, is likely truly obese. Yet both of them may show up as "overweight" on the height -weight or BMI charts - when neither of them can be accurately called that. The charts are only guides not scripture.

Though imperfect, it's still good that there are health science charts available that outline desirable weights for a given height, because, despite plenty of exceptions (like the two imaginary five-foot women above), reasonable guidelines provide a reality check. Without them, some people with anorexia nervosa, or with cultural biases towards seeing "too fat" (I think of the "perfect" Italian-American toddler of 1950 - with dimpled dimples on all four cheeks); or "too thin" (I think high fashion, the "social x-rays" of today and yesterday, on whom clothes drape as if still on the hanger) as ideal body types, might have no clue that their view is not considered a healthy one by experts in human health.

• The essence of having a lot of excess fat remains true on both sides of the line between obesity and overweight, and that's that it's easiest, once established as either very overweight or obese, to keep getting fatter. The forces push away from normal weight, and not back to it.
• For a couple of generations, physicians (and nutritionists) have been claiming that, when it comes to maintaining an ideal body weight, it's really very simple. All that matters is how many calories are consumed, minus how many calories are expended. That's it. More in than out, you gain. More out than in, you lose. End of discussion, over and out.

• Well, it turns out that things aren't so simple, after all, and those in the know are singing a different tune There are real physiologic forces that make it very, very easy to get fatter, even when a person is bound and determined to go the other way. Science is now supporting what many overweight people have complained about for years- there does seem to be a set point for fatness, that in them, means they have to starve to lose weight, or at least feel that way (like they are starving). Their claim that they have "no energy" unless they eat and eat and eat is now supported by the most sophisticated biology. As is the frequent claim of the fatter -than-they-want-to-be that any extra calories "go directly to my hips", that is: gets rapidly turned straight into more fat.

Of course, a surplus of calories does get stored as fat, and using up of ingested calories ( to avoid a surpus) does depends on our activity. It's not that those basic facts are not true, it's just that there is a whole lot more to it.

• Having a good amount of muscle tissue helps in burning off calories, because when a given person is bulked up a bit (meaning has developed her muscles), she'll use up more calories over a day than that same person with less muscle weight. Understanding that idea has helped many people improve fitness and decrease excess fat.
• So, yes, body composition helps set metabolism. There is more to it than muscle though, it isn't just biceps and quads and overall skeletal muscle mass that sets our metabolism. There is another major player that was never suspected to play any active role...and, that's fat itself!

Classically, body fat has always been viewed as a passive blob that has nothing to do with our metabolism- not directly, anyway. Big-time fat has been disparaged as an obstacle in fitness because it makes the body less agile, and puts strain on joints because of extra weight-load, but - sort of like stuffing in a mattress- somehow fat has never been seen as other body tisues, like muscle, say, in doing much. Well, fat is not like muscle, that's for sure, but it's not just stuffing. It's something like your thyroid gland or pancreas, it functions as an endocrine gland and it makes hormones.

• Fat acts as a gland and makes hormones.
• Fat is active in regulating itself - being fat actually influences our appetite - our perceived need for food.
• Worse, being very fat also slows down how quickly fat "burns" off if we resist the hunger and eat too little to sustain ourselves. Fat signals our central nervous system and the endocine glands, and that these signal each other back, all conspiring to keep those chubby bodies as they are, and thwarting our desire for normal weight. Learning more about this particular "conspiracy theory" might help explain how having excess fat factors in to weight loss strategies . That knowlege might at least help those of us struggling to at least not continue to gain more (I'm hoping, anyway).

• It's worth a try, because it's got to be done. If you (like me) are either overweight or obese, and getting fatter with the passing years, arrest and reversal of the process is required to avoid a downward spiral towards diabetes, heart disease, and arthritis.
  • The last two are particluarly pernicious because they can make activity difficult or impossible, and that leads to ...more fat.

• What's BMI?
  • BMI is the Body Mass Index - the standard measurement used in public health when studying obesity. BMI is the amount of weight per surface area of the body - in other words, in the metric system, BMI is kg per square meter, and using English units, it would be pounds per square foot.
• Why is it important?
  • It's been the official measurement for discussing obesity in health publications in the USA since 1998. Obesity is defined as a BMI of 30.0 or higher and is further divided into obesity class I (BMI =30.0-34.9), obesity class II (BMI = 35.0-39.9), and obesity class III (BMI = 40+).

No doubt that if a "naturally" obese person is subjected to a prison work camp for long enough, they will not remain fat. Yet, short of that extreme of food deprivation and forced physical activity, some people will always tend to be heavy, even with diet and daily activity levels that would keep another person thin. Similarly, there are people of near-ideal weight who basically have to be force fed and chained down into a sedentary life style in order to put on much fat.

The language I use is colorful, but accurate.

The studies have actually been done that offer excellent evidence for these points. Oh, and another thing - that emaciated fat person freed from the camp will almost certainly become obese again, and that healthy weight person freed from an agreement to sit still in a room and gorge for 6 weeks will almost certainly become thin again, when each is offered free choice of food and activity.

Now, part of that reason may lie in the choices made by each one of them, and those kinds of behavioral patterns - the weight gaining and weight losing ones, are explored in the article, Behavioral Weight Control...but there's more to it.

The fat cells of fat people seem to hold on to their fat and resist getting smaller, and the fat cells of thin people tend to do just the opposite.

• Scientists have offered an explanation that involves hormones so newly discovered that most of us have never heard of them. Adipose tissue makes some of these hormones.
• That explanation involves a change in how we think of fat,: it's not just stored calories, not "dead weight" , not just padding : fat is an endocrine gland.
• There's a name for the hormones, as a group, that the cells of body fat make: the adipocytokines. The fat cells are adipocytes and the hormones, again, adipoctyto-kines.

There's more to being "Very Overweight/Obese" than just making more of these adipocytokines , there is also the fat cells' (and other tissues') reaction to them, and to other hormones involved in fat and metabolism regulation. Just as Type II Diabetics are relatively resistant to the effects of insulin, "obese subjects remain hyperphagic despite their high circulating leptin levels, indicating hypothalamic insensitivity to leptin."(Katagiri H. Yamada T. Oka Y. Adiposity and cardiovascular disorders: disturbance of the regulatory system consisting of humoral and neuronal signals. Circulation Research. 101(1):27-39, 2007 Jul 6)

• Once coronary artery disease develops, engaging in strenuous exercise becomes more complicated- since angina may accompany physical exertion.

Medical & Scientific Journals

• Steppan et al. : The hormone resisten links obesity to diabetes. Nature 409:307-12, 2001
• Flier J et al.: Severly imparied adipsin expression in genetic and acquired obesity. Science 237:405-408, 1987
• Norata GD et al.: Plasma resistin levels correlate with determinants of the metabolic syndrome. Eur J Endocrinol 156:279-84. 2007
• Katagiri H. Yamada T. Oka Y. Adiposity and cardiovascular disorders: disturbance of the regulatory system consisting of humoral and neuronal signals. Circulation Research. 101(1):27-39, 2007 Jul 6. (Recent review with 138 references)
• Savage PD. Ades PA. The obesity epidemic in the United States: role of cardiac rehabilitation. Coronary Artery Disease. 17(3):227-31, 2006 May
• Himes, Christine L.: Obesity in Later Life: An Overview of the Issues. Research On Aging, vol. 26, no. 1, pp. 3-12, January 2004
• Faith, Myles S.; Fontaine, Kevin R.; Cheskin, Lawrence J.; Allison, David B.: Behavioral Approaches to the Problems of Obesity. Behavior Modification, vol. 24, no. 4, pp. 459-493, September 2000
• Speiser et al: CONSENSUS STATEMENT: Childhood Obesity. Journal of Clinical Endocrinology and Metabolism - Volume 90, Issue 3 (March 2005) - Copyright © 2005 The Endocrine Society

Medical Textbooks

• David G. Gardner and Dolores Shoback: Greenspan's Basic and Clinical Endocrinology 8th Edition, Copyright © 2007 by The McGraw-Hill Companies, Inc ISBN 10: 0-07-144011-9

• External Links:

• http://win.niddk.nih.gov/index.htm

The website of the leading researchers in the European Union, current research on how the brain and hormones work together, much is on a professional and scientific level - some is on a lay level. Worth a look.

• Fighting Back Against Obesity