Inclusion Criteria:  1. Adults aged 18-65 inclusive. 2. People with a body mass index (BMI) between 25.0 and 39.9 kg/m2 3. Stable weight for past 3 months (≤5% change in preceding 3 months as reported by participants).  4. Females of childbearing potential must be on highly effective contraception and have a negative pregnancy test within 7 days of their study visits. NOTE: Subjects are considered not of childbearing potential if they are surgically sterile (i.e. they have undergone a hysterectomy, bilateral tubal ligation, or bilateral oophorectomy) or they are postmenopausal.  5. Fluent in English and able to understand and complete questionnaires. 6. Willing and able to provide written informed consent and comply with the study protocol.  Exclusion Criteria:  Female subjects who are pregnant or breast-feeding. Female subjects of childbearing potential who are not on highly effective contraception. Post-menopausal women who have not had a period of spontaneous amenorrhea for more than 1 year. Previous bariatric surgery. Type 1 or 2 diabetes. Current use of weight loss medications or taking medication that affects appetite, e.g., antidepressants such as mirtazapine. Food intolerances, or allergies, that would make fixed energy meal and/or ad libitum meal unable to be performed. Impairment of sense of taste and/or smell, as per subject assessment and direct questioning. Poor dental hygiene or oral pathology. Current smokers of tobacco products. Any other factor making the participant unsuitable in the view of investigator.