One of the primary risk factors for the development of diabetes is obesity. While even moderate weight loss achieved by dieting can lead to improvements in metabolic health, reduced-calorie diets are notoriously difficult to sustain. Over the past decade, a number of groups have shown that low protein diets are associated with metabolic health in both rodents and humans. In particular, specific building blocks of protein- the branched chain amino acids (BCAAs) leucine, isoleucine, and valine - are associated with insulin resistance and diabetes in humans. Blood levels of the BCAAs decrease in humans fed a low protein diet, and we recently showed that reducing either dietary BCAAs or protein rapidly restored normal body composition and insulin sensitivity to diet-induced obese mice without reducing calorie intake. Current study will test the metabolic role of dietary BCAAs in humans by completing an adequately powered, randomized controlled study. A total of 132 subjects stratified by gender will be randomized to one of three groups: 1) Control; 2) Low Protein; 3) Low BCAA. Subjects in each group will replace two meals a day (and 2/3rds of their baseline dietary protein) with meal replacement beverages based on either complete protein powder or a BCAA-free medical food for two months. Primary outcomes will be weight and fasting blood glucose levels. A number of secondary outcomes will also be assessed and blood, adipose, and fecal samples will be collected for integrated transcriptional and metabolomic pathway analysis to identify and compare the metabolic pathways affected by low protein and low BCAA diets.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Meal replacement beverages made with whey protein
meal replacement beverages (MRBs) made with BCAD2 powder (lacking BCAAs).
meal replacement beverages(MRBs) containing low protein
University of Wisconsin-Madison School of Medicine and Public Health
Madison, Wisconsin, United States
Change in weight
Change in participant weight
Time frame: Baseline, 30 (±7)days, 60(-3 to +7)days, 134(+7) days
Change in fasting blood glucose level
Change in the participant's fasting blood glucose level
Time frame: Baseline, 30 (±7)days, 60(-3 to +7)days, 134(+7) days
Change in the body composition (adipose mass) as measured by DXA/BIS
Dual energy X-ray absorptiometry (DXA) is a standard technique for the determination of body composition. DXA results will be used to calculate fat and lean mass composition. Total body Bioelectrical Impedance Spectroscopy (BIS) is a minimal risk procedure which enhances DXA as it permits the determination of intracellular water.BIS is used to calculate fat and fat-free mass composition. A formula will be used to combine BIS fat-free mass composition and DXA lean mass composition corrected by limb length, which allows a surrogate measurement of muscle mass.
Time frame: Baseline, 60(-3 to +7)days
Change in Insulin sensitivity
Insulin resistance will be measured by HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) method. Insulin resistance reveals the dynamics between the participant's baseline (fasting) blood sugar and the responsive insulin levels. HOMA-IR healthy range: 1.0 (0.5-1.4), less than 1.0 means participant is insulin-sensitive which is optimal, above 1.9 indicates early insulin resistance, above 2.9 indicates significant insulin resistance.
Time frame: Baseline, 30 (±7)days, 60(-3 to +7)days, 134(+7) days
Change in Fibroblast growth factor 21 (FGF21) levels
Fibroblast growth factor 21 (FGF21) is a hormone which regulate insulin signalling in response to nutritional status. Levels of FGF21 induced in response to low protein diet and fasting will be measured using enzyme-linked immunosorbent assay(ELISA) assay.
Time frame: Baseline, 30 (±7)days, 60(-3 to +7)days
Change in Energy expenditure as measured by resting metabolic rate
Energy expenditure will be calculated from resting metabolic rate. Resting metabolic rate is the energy required by the body to perform the most basic functions when body is at rest.
Time frame: Baseline, 60(-3 to +7)days
Change in Muscle function as measured by jump maximal height
Jumping mechanography will be used to quantify muscle function. Jumping mechanography involves 3 supervised jumps on a force measurement platform. Analysis will be conducted on variables associated with the highest achieved jump height of the 3 trials. In Jumping mechanography, participants perform two-leg maximal countermovement jumps on a force plate (Leonardo, Novotec, Pforzheim, Germany). Maximal jump height(meter) will be calculated using Leonardo software.
Time frame: Baseline, 60(-3 to +7)days
Change in Muscle function as measured by jump velocity
Jumping mechanography will be used to quantify muscle function. Jumping mechanography involves 3 supervised jumps on a force measurement platform.Analysis will be conducted on variables associated with the highest achieved jump height of the 3 trials. In Jumping mechanography, participants perform two-leg maximal counter-movement jumps on a force plate (Leonardo, Novotec, Pforzheim, Germany). Jump velocity \[meter/sec\] will be calculated using Leonardo software.
Time frame: Baseline, 60(-3 to +7)days
Change in Muscle function as measured by relative power of jump
Jumping mechanography will be used to quantify muscle function. Jumping mechanography involves 3 supervised jumps on a force measurement platform.Analysis will be conducted on variables associated with the highest achieved jump height of the 3 trials. In Jumping mechanography, participants perform two-leg maximal countermovement jumps on a force plate (Leonardo, Novotec, Pforzheim, Germany). Relative power of jump \[Watt/kg\] will be calculated using Leonardo software.
Time frame: Baseline, 60(-3 to +7)days
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