The purpose of this research is to test the effects of the Dietary and Physical Activity Guidelines for Americans on health and on eating and exercise behaviors.
The Dietary Guidelines for Americans (DGA), which include the Physical Activity Guidelines for Americans (PAGA), is the primary United States (U.S) government resource for weight control. The researchers propose that chronic, low grade inflammation (CLGI) limits weight control by acting upon physiological and behavioral factors that moderate weight control. Diet and exercise reduce CLGI and provide weight control, but no one has investigated the efficacy of the DGA and PAGA to reduce CLGI, whether reduced CLGI promotes greater weight control, and the moderating roles of physiological and behavioral factors on the association of reduced CLGI with weight control. To accomplish this, the researchers will conduct a 6-month trial in 224 obese adults; a 3-month controlled feeding trial with four dietary arms; 1) DGA with weight loss, 2) Western diet with weight loss,3) DGA diet weight maintenance, 4) Western diet weight maintenance. Each dietary arm will have PAGA-recommended exercise and non-exercise arms. Post-trial is a 3-month weight maintenance period. The primary outcome is change in C-reactive protein (CRP), a marker of CLGI. The results will inform the DGA and PAGA; thereby helping clinicians, public health workers, and policymakers to improve the health of Americans.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
NONE
Intake of DGA weight loss 8 day rotating menu \& PAGA-recommended exercise
Intake of DGA weight loss 8 day rotating menu \& no exercise
Intake of DGA weight maintenance 8 day rotating menu \& PAGA-recommended exercise
Change in C-reactive protein (CRP)
The effect of diet and exercise on CRP
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Relative reinforcing value (RRV) of energy-dense snack foods
The effect of consuming a healthy DGA style or a Western style diet during weight loss and weight maintenance on the RRV of energy-dense snack food using a computer choice paradigm. For the computer choice paradigm subjects click the mouse button to play a simulated slot machine games to earn points toward receiving a portion of food or being able to do a non-food related sedentary activity (e.g., watching TV).
Time frame: Weeks 0,12, 24
Relative reinforcing value (RRV) of exercise
The effect of achieving the DGA recommended amounts of exercise during weight loss and weight maintenance on relative reinforcing value of exercise compared to a sedentary activity alternative using a computer choice paradigm. For the computer choice paradigm subjects click the mouse button to play a simulated slot machine games to earn points toward being able to do a chosen physical activity, such as walking on a treadmill, or a sedentary activity (e.g., watching TV).
Time frame: Weeks 0,12, 24
Fat and carbohydrate oxidation
The effect of diet and exercise on carbohydrate and fat oxidation in response to meals and exercise as measured by whole-room calorimetry
Time frame: Weeks 0,12
Food Cognitive Interference
The effect of diet and exercise on food cognitive interference, one of the three cognitive domains of executive function, using a computerized Food Stroop test.
Time frame: Weeks 0, 12, 24
Cognitive flexibility
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Intake of DGA weight maintenance 8 day rotating menu \& no exercise
Intake of Western-type weight loss 8 day rotating menu \& PAGA-recommended exercise
Intake of Western-type weight loss 8 day rotating menu \& no exercise
Intake of Western-type weight maintenance 8 day rotating menu \& PAGA-recommended exercise
Intake of Western-type weight maintenance 8 day rotating menu \& no exercise
The effect of diet and exercise on cognitive flexibility, one of the three cognitive domains of executive function, using a computerized Trail-Making test B/A.
Time frame: Weeks 0, 12, 24
Working memory
The effect of diet and exercise on cognitive flexibility, one of the three cognitive domains of executive function, using the Wisconsin Card Sorting Task.
Time frame: Weeks 0, 12, 24
Inflammation
The effect of diet and exercise on plasma pro-inflammatory cytokines (e.g., Il-6, MCP-1, TNF-alpha) and anti-inflammatory cytokines (e.g., IL-10, Soluble TNF receptor I and II)
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Change in adipokines
The effect of diet and exercise on plasma adipokines (e.g., adiponectin, resistin)
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Change in myokines
The effect of diet and exercise on plasma myokines (e.g., BDNF, Myostatin, FGF-21, Irisin)
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Change in bile acids
The effect of diet and exercise on plasma bile acids (i.e., glycocholic acid, glyco-CDCA, glyco-HDCA, hyocholic acid, hyodeoxycholic acid)
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Change in blood lipids
The effect of diet and exercise on cholesterol, HDL, triglycerides
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Change in weight control moderators
Questionnaires (i.e., three-factor eating questionnaire, reward base eating, food attitudes and behavior survey) that when scored provide a single number will be used to determine the moderating effect of self efficacy, restraint and disinhibition maintaining diet and exercise changes
Time frame: Weeks 0,12, 24
Change in humoral biomarkers of eating behavior
The effect of diet and exercise on ghrelin, leptin, thyroid hormones, gut peptides, fatty acids
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Gene expression profiles of glucose oxidation
The effect of diet and exercise on gene expression profiles associated with glucose oxidation (i.e., hexokinase, phosphofructokinase, pyruvate dehydrogenase kinase 4, peroxisome proliferator-activated receptor alpha gene expression)
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24
Gene expression profiles of fat oxidation
The effect of diet and exercise on on gene expression profiles associated with fat oxidation (i.e., fatty acid translocase, fatty acid synthase, acetyl Co-A carboxylase 2, stearoyl Co-A desaturase gene expression)
Time frame: Weeks 0, 2, 4, 6, 8, 10, 12, 24