Here is the design of a clinical trial:

Official Title: Role of Long-term Dietary Sweetness Exposure on Sweetness Preferences

Included conditions:
- Food Preferences

Study Armgroups:
- {'label': 'Regular dietary sweetness exposure - Control', 'type': 'ACTIVE_COMPARATOR', 'description': 'Regular dietary sweetness exposure (RSE) - The RSE group consumes a diet with 25 - 30 % energy from sweet tasting foods, for 6 months.', 'interventionNames': ['Other: Dietary intervention']}
- {'label': 'Low dietary sweetness exposure - Experimental', 'type': 'EXPERIMENTAL', 'description': 'Low dietary sweetness exposure (LSE) - The LSE group consumes a diet with 10 - 15 % energy from sweet tasting foods, for 6 months.', 'interventionNames': ['Other: Dietary intervention']}
- {'label': 'High dietary sweetness exposure - Experimental', 'type': 'EXPERIMENTAL', 'description': 'High dietary sweetness exposure (HSE) - The HSE group consumes a diet with 40 - 45 % energy from sweet tasting foods, for 6 months.', 'interventionNames': ['Other: Dietary intervention']}

Interventions:
- {'type': 'OTHER', 'name': 'Dietary intervention', 'description': 'Varying the exposure to sweetness via diet manipulation.', 'armGroupLabels': ['High dietary sweetness exposure - Experimental', 'Low dietary sweetness exposure - Experimental', 'Regular dietary sweetness exposure - Control']}

Primary Outcomes:
- {'measure': 'Change in preference score.', 'description': 'Measured during preference testing, using Ranking on a scale methodology (scale anchored at 0: Dislike extremely; 50: Neither dislike or like; 100: Like extremely) in a series of test foods.', 'timeFrame': 'from month 0 to month 6.'}

Please estimate the sample size based on the assumption: 
The study assumes a parallel design with 3 groups, two repeated measures (baseline vs 6-month) with a correlation of 0.7, a power of 80%, a significance level of 0.05, and a potential dropout rate of 20%.
Sample size estimation
        The sample size calculation is based on our primary outcome: change in most preferred sweet taste concentration from 0â6Â months. Previous studies have established that it is possible to detect shifts in preferred concentration from preference tests [36, 52]. For example, looking at the study of Liem and de Graaf [52] and the change in most preferred concentration, we can observe that mean ranking score for the sweet exposure group changed by around 0.4 and by around 0.6 for the sour exposure group from baseline to after exposure, which is around 10%. Therefore, the effect size of 0.1 was considered to be a relevant and meaningful effect size for our study, and was used to estimate the sample size. We estimate that 147 participants are needed to detect an effect size of 0.1, assuming a parallel study with 3 groups, with two repeated measures (baseline vs 6-month, correlation between measures of 0.7), and a power of 80% at a significance level of 0.05. To account for a potential dropout of 20%, 180 individuals will be enrolled in the study.