Discovering the effect of plant natural products on appetite and fullness in healthy overweight adults

The study aims to investigate the effectiveness of the satiety-prolonging and appetite-suppressing effects of natural plant extracts, including Momordica charantia, Caralluma fimbriata, Gymnema sylvestre, and Humulus lupulus, on healthy, overweight individuals. This randomized, double-blinded, crossover study will be conducted at the Be Active Sleep Eat (BASE) Facility, Monash University. The study consists of an initial screening and five treatment sessions. Participants first complete an online pre-screening questionnaire to determine eligibility. Those who meet the criteria are invited for an in-person visit at the BASE Facility, where researchers measure their height and weight, provide a detailed briefing on the study procedures, and obtain informed consent. Each participant required to attend a total of 5 treatment sessions (4 interventions and one placebo). Participants are advised to avoid alcohol and strenuous exercise for 24 hours before each treatment session and to fast from 9 PM the previous night. On the day of each session, participants arrive at the facility at 8 AM. Researchers measure their height, weight, and body composition using multi-frequency Bioelectrical Impedance Analysis (mBIA). Throughout each visit, participants complete several questionnaires assessing their feelings related to appetite, mood, food cravings, gastrointestinal condition, and perceptions of the food provided. Participants then consume a fixed-calorie breakfast (approximate calorie content: 1700 kJ). They are advised to finish the breakfast within 15 minutes. Two and a half hours later, they ingest a treatment capsule containing 500 mg of either a plant extract (Momordica charantia, Caralluma fimbriata, Gymnema sylvestre, or Humulus lupulus) or a placebo. An hour after capsule administration, participants eat a standard lunch and can eat as much as they like within a duration of 30 minutes. After the standard lunch, participants complete the same questionnaires again until 2 PM. Additionally, they maintain a 24-hour diet diary until 12 PM the following day, documenting all food and beverage intake. A seven-day washout period is provided between each treatment session to ensure accurate results. To ensure adherence to the intervention, trained researchers will directly supervise participants during key aspects of the study, including the consumption of study capsules, meals, and the completion of questionnaires.