Cellular Dynamics of Subcutaneous Fat Distribution in Obese Women

Not Applicable

Completed

Brief Summary: The body shape of obese women varies between having the majority of fat either above the waist ("apple" shape) or below the waist ("pear" shape). The study will investigate what restricts: apple"-shaped women from being "pear"-shaped at the cellular level. Since "pear" shaped women tend to have better health, this study will open the door to future research in regulating body shape and thus improving health.

Detailed Description: Adipose tissue expandability and the distribution of stored fat in the body are stronger predictors of health risk. A better understanding of the factors that determine regional fat mass growth may lead to developing new strategies for prevention or treatment of metabolic complications of obesity. The objective of this proposal is to study the responsiveness of different fat depots to adipogenic stimulation in upper-body and lower-body obese women.

Recruitment & Eligibility

Inclusion Criteria

You are a pre-menopausal woman between 18-40 years of age
Your Body Mass Index (BMI, weight-to-height2 ratio) is 27 - 38 kg/m2, inclusive
The ratio of your waist-to-hip circumferences is either >0.84 ("apple"-type body shape) or <0.77 ("pear"-type body shape)
You are willing to undergo a drug intervention for 16 weeks
You are willing to drink heavy water [similar to the ordinary water that is highly enriched in the naturally occurring stable (non-radioactive) form of hydrogen, deuterium; also called deuterium-labeled water] for 8 weeks before the beginning and during the second half of the drug intervention; you will need 24-hours access to a refrigerator for storage of the water.
You agree to use a double barrier method as a form of birth control to prevent pregnancy. Oral contraceptives (birth control pills) are not allowed in the study. Acceptable methods of birth control are condoms, spermicide, IUD (intrauterine device, must be hormone free - see list in clinic), diaphragm and abstinence. An example of a double barrier method would be condoms plus spermicide, etc.

Exclusion Criteria

You have gained or lost more than 4.5 lb (2 kg) in the last 3 months
You have had significant changes in the diet or level of physical activity within the past month
You have a blood sugar of greater than 100 or a diagnosis of diabetes.
You have abnormal liver enzyme values from your blood work
You have a history of heart, kidney, lung, liver, and thyroid disease
You have an average blood pressure >140/90 at your screening visit
Have you had a positive test for human immunodeficiency virus (HIV), hepatitis B or hepatitis C?
You require chronic use of medications including diuretics, steroids, thyroid hormones, and adrenergic-stimulating agents (bronchodilators, nasal decongestants)

Arm && Interventions

Group	Intervention	Description
Drug	Pioglitazone	Administration of pioglitazone to upper- and lower-body obese women
Placebo	Placebo	Administration of placebo to upper- and lower-body obese women

Primary Outcome Measures

Name	Time	Method
In Vivo Adipose Cell Formation (Adipogenesis)	Change from baseline in adipogenesis at 16 weeks	Following the consumption of water labeled with the stable isotope deuterium (2H2O; heavy water), adipose tissue biopsies from the subcutaneous abdominal and femoral (thigh) depots will be collected. The 2H from the heavy water is enriched into the DNA of newly synthesized cells. Measures of DNA synthesis (obtained via gas chromatography and mass spectrometry analysis of 2H-enrichment) denote new adipose cell formation, or adipogenesis. The primary outcome is to assess the change (from baseline) in adipose cell formation rates (i.e. adipogenesis) in response to 16-weeks of pioglitazone versus the control group.

Secondary Outcome Measures

Name	Time	Method
Visceral Adipose Tissue (Percentage of Total Abdominal Adipose Tissue)	Change from baseline in visceral fat at 16 weeks	The volume of fat tissue around the internal organs in the abdomen (visceral adipose tissue; VAT) and underneath the skin (subcutaneous abdominal adipose tissue; scABD) will be determined by Magnetic Resonance Imaging (MRI) of the abdominal region. VAT:total abdominal AT (TAT) reflects the percentage of abdominal fat that is VAT and is calculated as VAT/(scABD AT + VAT).
Lipid Accretion in the Liver (Intra-hepatic Lipid; IHL)	Change from Baseline in intra-hepato-cellular lipid at 16 weeks	Lipid accretion in the liver cells will be measured using 1H-MRS of the liver.
Matsuda Index (Measure of Insulin Sensitivity)	Change from Baseline in Matsuda Index at 16 weeks	Insulin sensitivity (glucose tolerance) will be assessed using an oral 75 g oral glucose tolerance test (OGTT) after an overnight fast. Blood samples will be collected at 0, 30, 60, 90, and 120 min after glucose administration to measure serum glucose and insulin. Insulin sensitivity was calculated using the Matsuda insulin sensitivity index \[10,000/ √(glucose 0' x insulin 0') X (mean glucose OGTT x mean insulin OGTT)\]. A higher value denotes increased insulin sensitivity.