|
Not all fat created equal
May 07, 2008It has long been known that type 2 diabetes is linked to obesity, particularly fat inside the belly. Now, researchers at the Joslin Diabetes Center have found that fat from other areas of the body can actually reduce insulin resistance and improve insulin sensitivity.
In a study published in the May issue of Cell Metabolism, a team lead by C. Ronald Kahn, M.D. found that subcutaneous fat -- fat found below the skin, usually in the hips and thighs -- is associated with reduced insulin levels and improved insulin sensitivity.
"This points to a new opportunity to find substances made by subcutaneous fat that may actually be good for glucose metabolism,'' said Dr. Kahn, Head of the Joslin Research Section on Obesity and Hormone Action and the Mary K. Iacocca Professor of Medicine at Harvard Medical School. "If we can identify how subcutaneous fat does this, we will have a big clue as to where to look for these substances."
Kahn noted that obesity in the abdominal or visceral area -- the classic "beer belly" or "apple" shape -- increases the risk of diabetes and mortality, and said it has been thought that obesity in subcutaneous areas -- the "pear" shape -- might decrease such risks.
"We started out to answer the basic question of whether fat inside the belly is bad for you because of where it is located, or is abdominal fat itself different from fat in other places," said Kahn, an internationally recognized researcher in diabetes and metabolism.
To test if the differences were due to anatomic location or intrinsic properties of the fat deposits themselves, transplantations were performed in mice. The researchers found that when subcutaneous fat was transplanted into the abdominal area, there was a decrease in body weight, fat mass, glucose and insulin levels and an improvement in insulin sensitivity. By contrast, transplantation of abdominal fat into either the abdominal or subcutaneous area had no effect.
The paper concludes that subcutaneous fat is intrinsically different from visceral fat and may produce substances that can improve glucose metabolism.
"The surprising thing was that it wasn't where the fat was located," Kahn said. "It was the kind of fat that was the most important variable. Even more surprising, it wasn't that abdominal fat was exerting negative effects, but that subcutaneous fat was producing a good effect. Animals with more subcutaneous fat didn't gain as much weight as they aged, had better insulin sensitivity, lower insulin levels and were improved all around."
Earlier studies in humans had shown that removal of subcutaneous fat by liposuction does not result in improvement of any aspect of metabolic syndrome, a collection of medical problems related to insulin resistance, but none had focused on possible good effects of this subcutaneous fat. However, one human study did show that obese individuals with high levels of both intra-abdominal and subcutaneous fat were more insulin sensitive than those with only high levels of intra-abdominal fat.
In addition, Kahn noted that a class of diabetes drugs called thiazoladines may cause patients to gain weight in the subcutaneous area, yet also improve insulin sensitivity.
Kahn said it is possible that subcutaneous fat may be producing certain hormones, known as adipokines, which produce beneficial effects on metabolism. These effects may offset the negative effects produced by abdominal fat.
The next step is to identify how subcutaneous fat produces these substances that improve metabolism and then find the substances themselves with the idea of creating a drug that can do the same thing.
"We're already trying to identify through the use of proteomics what is coming out of the different fat cells," Kahn said.
Joslin Diabetes Center
Kahn noted that obesity in the abdominal or visceral area -- the classic "beer belly" or "apple" shape -- increases the risk of diabetes and mortality, and said it has been thought that obesity in subcutaneous areas -- the "pear" shape -- might decrease such risks.
"We started out to answer the basic question of whether fat inside the belly is bad for you because of where it is located, or is abdominal fat itself different from fat in other places," said Kahn, an internationally recognized researcher in diabetes and metabolism.
To test if the differences were due to anatomic location or intrinsic properties of the fat deposits themselves, transplantations were performed in mice. The researchers found that when subcutaneous fat was transplanted into the abdominal area, there was a decrease in body weight, fat mass, glucose and insulin levels and an improvement in insulin sensitivity. By contrast, transplantation of abdominal fat into either the abdominal or subcutaneous area had no effect.
The paper concludes that subcutaneous fat is intrinsically different from visceral fat and may produce substances that can improve glucose metabolism.
"The surprising thing was that it wasn't where the fat was located," Kahn said. "It was the kind of fat that was the most important variable. Even more surprising, it wasn't that abdominal fat was exerting negative effects, but that subcutaneous fat was producing a good effect. Animals with more subcutaneous fat didn't gain as much weight as they aged, had better insulin sensitivity, lower insulin levels and were improved all around."
Earlier studies in humans had shown that removal of subcutaneous fat by liposuction does not result in improvement of any aspect of metabolic syndrome, a collection of medical problems related to insulin resistance, but none had focused on possible good effects of this subcutaneous fat. However, one human study did show that obese individuals with high levels of both intra-abdominal and subcutaneous fat were more insulin sensitive than those with only high levels of intra-abdominal fat.
In addition, Kahn noted that a class of diabetes drugs called thiazoladines may cause patients to gain weight in the subcutaneous area, yet also improve insulin sensitivity.
Kahn said it is possible that subcutaneous fat may be producing certain hormones, known as adipokines, which produce beneficial effects on metabolism. These effects may offset the negative effects produced by abdominal fat.
The next step is to identify how subcutaneous fat produces these substances that improve metabolism and then find the substances themselves with the idea of creating a drug that can do the same thing.
"We're already trying to identify through the use of proteomics what is coming out of the different fat cells," Kahn said.
Joslin Diabetes Center
Subcutaneous Fat News and Current Subcutaneous Fat Events RSSLifestyle can alter gene activity, lead to insulin resistance
A Finnish study of identical twins has found that physical inactivity and acquired obesity can impair expression of the genes which help the cells produce energy.
New technique determines that the number of fat cells remains constant in all body types
The radioactive carbon-14 produced by above-ground nuclear testing in the 1950s and '60s has helped researchers determine that the number of fat cells in a human's body, whether lean or obese, is established during the teenage years. Changes in fat mass in adulthood can be attributed mainly to changes in fat cell volume, not an increase in the actual number of fat cells.
Mom's obesity during conception phase may set the stage for offspring's obesity risk
The number of overweight and obese Americans continues to grow rapidly. Today, 50 percent of adults are overweight and up to 20 percent are obese. While the number of overweight/obese children is at an all time high, the steady increase of overweight infants -- individuals under 11 months old -- is alarming.
Modest gain in visceral fat causes dysfunction of blood vessel lining in lean, healthy humans
When lean healthy young adults gained about 9 pounds, the functioning of their blood vessel lining became impaired -- but shedding the weight restored proper functioning, according to a Mayo Clinic research report.
Fat on chest and upper back increases risk of insulin resistance
Upper trunk fat -- deposits of fat on the chest and back -- is associated with an increased risk of insulin resistance, a condition that is a precursor of type 2 diabetes, according to a study led by researchers at the San Francisco VA Medical Center (SFVAMC).
Belly fat may drive inflammatory processes associated with disease
As scientists learn more about the key role of inflammation in diabetes, heart disease and other disorders, new research from Washington University School of Medicine in St. Louis suggests that fat in the belly may be an important promoter of that inflammation.
Exercise important in reducing size of abdominal fat cells
Reducing the size of abdominal fat cells - which are a risk factor for diabetes and heart disease - takes more than cutting calories, according to new research from Wake Forest University Baptist Medical Center.
Fat cells around coronary arteries may play a role in heart disease
The fat cells that surround coronary arteries may play a central and previously unrecognized role in development of cardiovascular disease, according to a study by University of Iowa researchers.
Injection of synthetic polymer may improve facial wasting syndrome associated with HIV
Facial injections of polylactic acid, a synthetic biodegradable polymer, may help improve the debilitating facial lipoatrophy (loss of fat in the face) associated with HIV infection and its treatment.
Potential heart benefit found in stem cells
Stem cell transplantation is among one of the most exciting and hotly debated areas of medical research today.
More Subcutaneous Fat News Articles
| Serial Changes in Subcutaneous Fat Thicknesses of Children & Adults (Monographs in Paediatrics) by Alex F. Roche, R. B. Reed, R. M. Siervogel | |
| SKINFOLD MEASUREMENT; A METHOD OF DETERMINING SUBCUTANEOUS FAT by Kathleen R. Stitt | |
| Effect of pre-slaughter factors on fatty acids in subcutaneous and intramuscular fat of wethers by Bronislaw Borys | |
| The distribution of subcutaneous fat in childhood and adolescence (Fels monograph series) by Earle L Reynolds |
| © 2008 BrightSurf.com |