The goal of this clinical trial is to investigate whether a Ketogenic Diet (KD) can increase Total Energy Expenditure (TEE), while benefiting appetite, during weight loss maintenance in reduced-obese individuals.
The total duration of the intervention will be 10 weeks. Participants will first undergo 4 weeks of a low-energy diet (LED), aiming to induce a minimum of 5% weight loss (weight loss phase). Those who achieve at least a 5% weight loss will then be randomized (1:1) to a 6-week weight loss maintenance (WLM) diet, either a KD or an isocaloric low-fat diet, with the first 2 weeks being a gradual refeeding.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
20
Participants will be provided food to meet the ketogenic diet prescription for the 6-week weight maintenance phase.
Participants will follow a commercial low-energy diet and be provided with meal replacements for 4 weeks aiming to achieve a minimum of 5% weight loss.
Participants will meet weekly with a registered dietitian, for a 20-minute consultation throughout the entire study period (10 weeks) to increase engagement and improve adherence and retention.
University of Alabama at Birmingham
Birmingham, Alabama, United States
RECRUITINGChange from baseline total energy expenditure
Total Energy Expenditure (TEE) refers to the total amount of energy (calories) your body uses in a day. Twenty-four-hour EE and RQ will be measured inside the whole room indirect calorimeter (chamber) following standard procedures
Time frame: Baseline, week 6, week 10
Change in appetite ratings
Subjective appetite ratings are personal feelings or perceptions about hunger, fullness, desire to eat (DTE), and prospective food consumption (PFC) usually measured using self-reported scales ranging from "not at all" to "extremely". Subjective appetite ratings (hunger, fullness, DTE and PFC) will be measured using a validated 10cm visual analog scale which will be given to the participants inside the chamber before meals.
Time frame: Baseline, week 6, week 10
Change in total body composition
Bioimpedance analysis (BIA) will be used to measure fat mass, fat-free mass, total, extra, and intra-cellular water.
Time frame: Baseline, week 4, week 6, week 10
Change in total body composition
FM, bone mass, and lean body mass will be determined by dual-energy X-ray absorptiometry (iDXA instrument, GE Healthcare Lunar, Madison, WI) with the use of software version 1.5g (Lunar Corp).
Time frame: Baseline, week 4, week 6, week10
Change in fasting insulin
Circulating (serum) fasting insulin will be measured using validated methods
Time frame: Baseline, week 6, week 10
Change in fasting cholecystokinin
Circulating (plasma) fasting cholecystokinin will be measured by RIA.
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Participants will have food provided to meet the standard low-fat diet prescription for the 6-week weight maintenance phase.
Time frame: Baseline, week 6, week 10
Change in fasting ghrelin
Circulating (plasma) fasting ghrelin concentrations will be measured by ELISA
Time frame: Baseline, week 6, week 10
Change in fasting glucagon-like peptide-1
Circulating (plasma) fasting total GLP-1 will be measured by ELISA
Time frame: Baseline, week 6, week 10
Change in fasting peptide YY (PYY)
Circulating (plasma) fasting PYY3-36 concentrations will be measured by ELISA
Time frame: Baseline, week 6, week 10
Change in total body weight
Body weight is the total amount a person weighs when measured on a scale.
Time frame: Baseline, week 4, week 6, week 10
Change in mechanical efficiency
Walking economy will be assessed using a submaximal treadmill test, performed 90 minutes after breakfast. Following a familiarization period, participant will walk on the treadmill at 2 miles/hour for 15 minutes, followed by another 15 minutes at 2.5 miles/hour.
Time frame: Baseline, week 6, week 10
Change in resting energy expenditure
Resting Energy Expenditure (REE) is the amount of energy (calories) your body needs to keep working while you're at rest. Participants will enter the chamber in the morning in the fasting state. REE will be measured while the participant is in the metabolic chamber.
Time frame: Baseline, week 6, week 10
Change in postprandial insulin
Circulating (serum) insulin measured before and 30, 60, 90, and 120 minutes after intake of breakfast with validated methods
Time frame: Baseline, week 6, week 10
Change in postprandial cholecystokinin
Circulating (plasma) cholecystokinin measured before and 30, 60, 90, and 120 minutes after intake of breakfast with RIA.
Time frame: Baseline, week 6, week 10
Change in postprandial ghrelin
Circulating (plasma) ghrelin measured before and 30, 60, 90, and 120 minutes after intake of breakfast with ELISA
Time frame: Baseline, week 6, week 10
Change in postprandial glucagon-like peptide-1
Circulating (plasma) total GLP-1 measured before and 30, 60, 90, and 120 minutes after intake of breakfast by ELISA
Time frame: Baseline, week 6, week 10
Change in postprandial peptide yy
Circulating (plasma) PYY3-36 concentrations measured before and 30, 60, 90, and 120 minutes after intake of breakfast with ELISA
Time frame: Baseline, week 6, week 10