Weight Loss and Hunger: Did we Get it Wrong All This Time?
Trial Snapshot
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- University of Ottawa
- Enrollment
- 40
- Locations
- 1
- Primary Endpoint
- Appetite measurements
Study Overview
Brief Summary
Weight loss is difficult and weight maintenance even worse. The principles of dieting dictate that to maintain weight loss, one has to eat less calories than they did before the diet. However, there is evidence to show that it may be the diet per se and not the weight loss that makes people more hungry and vulnerable to weight regain. This study will explore whether appetite control can be restored to normal levels through an individually tailored increase in calories after weight loss. If supported, the findings from this study could alter the way we view dieting.
Detailed Description
Weight loss reduces all components of the energy budget, i.e. resting energy expenditure (EE), the thermic effect of feeding and the energy cost of physical activities. The corollary of this observation is that to achieve energy balance at a lowered body weight (if EE is not increased through purposeful physical activity), energy intake (EI) needs to be kept at this lowered level of EE. While the math of the equation is simple, the operationalization has proven to be quite different. In fact, a dominant feature of weight loss is that it produces increases in hunger that appear within the first days, persist into weight loss and for at least a year after the intervention. As such, identifying strategies that abate changes in hunger and facilitate post-weight loss appetite control should be viewed as a central tenant of obesity interventions. However, data points to the possibility that it may well be the reduction in EI needed to produce weight loss that actually increases hunger. If this were to be the case, then forcing lower EI after weight loss likely exacerbates the state of increased hunger, paving the way for weight rebound. If there is somewhat a set value of EI for each individual, then current dietary strategies aimed at tailoring a food landscape conducive of reduced hunger with reduced EI needed to sustain weight loss, are destined to fail.
Primary hypotheses- The increase of EI to pre-weight loss values will significantly attenuate weight loss induced increases in hunger.
Secondary hypothesis- The increase of EI to pre-weight loss values will significantly attenuate weight loss induced metabolic adaptations (Greater than Predicted decreased in EE).
The increase of EI to pre-weight loss will significantly improve post weight loss ghrelin, PYY and GLP-1 responses.
Research plan- Fifty individuals living with obesity (25 men and 25 women BMI ≥ 30 kg/m2) will undergo a 20-week weight-loss intervention. After weight loss they will be randomly assigned to a 1-month experimental condition comprising of either : 1) a weight maintenance diet; or to 2) an increase of EI to pre-weight loss levels combined with increased exercise to maintain energy balance. A detailed investigation of energy balance variables will be conducted at all three time points.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Other
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to 55 Years (Adult)
- Sex
- All
- Accepts Healthy Volunteers
- No
Inclusion Criteria
- •18-55 years of age;
- •non-smoking;
- •obese class I-II (30 kg/m2 ≤ BMI < 40 kg/m2);
- •weight stable (± 2 kg during the 6 months prior to enrollment);
- •Sedentary (<2 times/week of 30 min of continuous exercise)
- •In addition, Females will be included if:
- •1) premenopausal (2 menses in the 3 months preceding testing, no increase in cycle irregularity in the 12 months preceding testing).
Exclusion Criteria
- •have a current diagnosis of an axis 1 psychiatric disorder (i.e. mood, anxiety and eating disorders);
- •currently use antidepressants, thyroid medication, or any medication that could affect appetite;
- •have a history of cardiac problems or symptoms suggestive of any cardiac condition;
- •have a current diagnosis or history of diabetes, confirmed by a measure of HbA1c during the screening visit;
- •have alcohol intake that exceeds recommendations or alcoholism, or current addictions to opiates, cocaine or stimulants;
- •currently taking monoamine oxidase inhibitors, pressor agents, warfarin, anticonvulsants, phenylbutazone, or tricyclic antidepressants;
- •have uncontrolled thyroid disease;
- •have any osteoarticular condition, or other reasons that would prevent them from achieving the proposed walking targets.
- •In addition, Females will be excluded if they:
- •are pregnant or planning to become pregnant over the course of the study;
- •are peri- or post-menopausal or have had surgically induced menopause.
Outcomes
Primary Outcomes
Appetite measurements
Time Frame: Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).
Desire to eat, hunger, fullness, and prospective food consumption (PFC) will be rated immediately before (after a 12 h overnight fast) and every 30 min\*3 h after the standardized breakfast on a 100-mm visual analog scale (VAS) adapted from Hill and Blundell. Scores range from 0 to 100 millimeters. For hunger, desire to eat, and prospective food consumption, higher scores indicate greater appetite. For fullness, higher scores indicate greater fullness (lower appetite). The satiety quotient will be calculated for each subject.
Secondary Outcomes
- Plasma concentrations of appetite-regulating hormones(Blood samples will be collected at each experimental session: Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), and onset of week 25 (after the 1-month weight-maintenance period).)
- Resting Energy Expenditure(Resting Energy Expenditure will be measured during the screening session (2 weeks before baseline), at baseline, end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Exercise Energy Expenditure(Accelerometer: worn for 7 days at each sampling period (screening, week 20 (end of weight loss intervention), weeks 22 and 24 (middle and end of weight maintenance). Exercise energy expenditure will be measured once per week during weight maintenance.)
- Total Energy Expenditure(The DLW dose will be consumed during the screening session, and participants will provide their first urine sample. A second sample will be collected on the following day, and a 3rd 7 days later.)
- Energy Intake(In-lab energy intake: Baseline, end of week 20 (after the weight-loss intervention), and at the onset of week 25 (after one month of weight maintenance). Free-living energy intake will be measured for 3 days after the screening session.)
- Food Reward(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period). The test lasts approximately 10 minutes.)
- Olfactory and Taste Performance(Olfactory and taste performance will be assessed during the in-laboratory at baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Body weight(Baseline, weeks: 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 21, 22, 23, 24, 25.)
- Height(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Fat-mass(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Fat-free mass(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Bone mineral content(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Thermic effect of Food(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Eating behaviour assessed using the Three-Factor Eating Questionnaire-51(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Health-related quality of life assessed using the 36-Item Short Form Health Survey(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
- Mood assessed using the Positive and Negative Affect Schedule(Baseline (1 week before the dietary intervention), end of week 20 (after the weight-loss intervention), onset of week 25 (after the 1-month weight-maintenance period).)
Investigators
Eric Doucet
Full Professor
University of Ottawa