The purpose of this study is to determine whether consuming additional leucine during calorie restriction induced weight loss has beneficial or harmful effects on multi-organ (liver, muscle, adipose tissue) insulin sensitivity, colonocyte proliferation rates, the gut microbiome, muscle mass and function, and bone mineral density in obese, postmenopausal women.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
43
Goal of 8 to 10% weight loss while consuming the recommended daily allowance of protein (i.e, 0.8 grams of protein per kg body weight per day).
Goal of 8 to 10% weight loss while consuming 150% of the recommended daily allowance of protein (i.e., 1.2 grams of protein per kg body weight per day) with the additional protein given in the form of whey protein, which has a high leucine content.
Washington University School of Medicine
St Louis, Missouri, United States
Change in muscle mass
We will measure total appendicular skeletal muscle mass by using dual-energy X-ray absorptiometry (DXA) and thigh muscle volume by magnetic resonance imaging (MRI)
Time frame: Baseline and at 10% weight loss in calorie restriction groups and ~6 to 7 months in the weight maintenance group
Change in muscle strength
We will evaluate muscle strength by administering maximum one repetition strength and isokinetic strength tests.
Time frame: Baseline and at 10% weight loss in calorie restriction groups and ~6 to 7 months in the weight maintenance group
Change in bone mineral density and bone mineral content
We will evaluate total bone mass and total body and regional bone mineral density by using dual X-ray energy absorptiometry (DXA).
Time frame: Baseline and at 10% weight loss in calorie restriction groups and ~6 to 7 months in the weight maintenance group
Change in skeletal muscle insulin sensitivity
We will evaluate insulin sensitivity using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotope labeled tracer infusions
Time frame: Baseline and at 10% weight loss in calorie restriction groups and ~6 to 7 months in the weight maintenance group
Change in bacterial populations found in the stool
Time frame: Baseline and at 10% weight loss in calorie restriction groups and ~6 to 7 months in the weight maintenance group
Change in cell proliferation (growth) rates in the colon
We will examine colon cell proliferation rates using stable isotope labelled tracer methods in conjunction with sigmoid colon biopsy samples
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Time frame: Baseline and at 10% weight loss in calorie restriction groups and ~6 to 7 months in the weight maintenance group
Determine the acute effect of leucine ingestion on skeletal muscle insulin sensitivity
We will evaluate insulin sensitivity using the hyperinsulinemic-euglycemic clamp procedure in conjunction with stable isotope labeled tracer infusions
Time frame: Prior to starting the weight loss or maintenance intervention
Determine the acute effect of leucine ingestion on muscle protein metabolism
We will assess rates of muscle protein synthesis, breakdown and net protein balance using stable isotope labeled tracer methods during postabsorptive conditions and during insulin infusion with or without leucine ingestion.
Time frame: Prior to starting the weight loss or maintenance intervention