Author(s): KEENAN, S., AL-REFAI, W., COOKE, M., CAMERA, D., Institution: SWINBURNE UNIVERSITY , Country: AUSTRALIA, Abstract-ID: 2508

INTRODUCTION:
Control of dietary variables, in particular intake of dietary energy (and subsequently energy balance) and protein, is important when undertaking human nutrition research studies. To adequately control energy balance and reach a certain level of protein intake, food and beverages are sometimes provided to participants, and in order to maintain high rates of adherence, these diets need to be effective, palatable and acceptable. This research reports on secondary diet acceptability and weight outcomes following short-term (i.e., 2-week) intermittent fasting, vegan, and omnivorous diets in recreationally active males.
METHODS:
Participants were randomly allocated to one of three dietary groups: Intermittent Fasting (IF, n=6, 26.7±2.1yrs, BMI 26.0±1.2), Omnivorous (Omni, n=7, 25.9±1.5yrs, BMI 24.6±1.4), and Vegan (n=9, 25.3±2.2yrs, BMI 25.8±1.3). Each group underwent a 2-week dietary intervention, where all meals and snacks were provided on a 3-day rotating menu, with changes made only to breakfast, lunch, and dinner (snacks provided were consistent). Food provision included frozen main meals, pre-packaged snacks, and protein supplements. The IF group consumed ~30% of their energy requirements via protein supplements on two, non-consecutive days per week, while the other 2 groups (euenergetic) consumed 100% of their estimated requirements daily. All 3 groups consumed an average of 1.6 grams of protein per kilogram of bodyweight per day. Weight was recorded daily, and diet acceptability was determined at the end of the study utilising the Food Acceptability Questionnaire, which consists of 7 questions utilising 7-point Likert scales.
RESULTS:
The IF group exhibited a significant weight loss of -1.8kg ± 0.5kg post-intervention, while the other groups did not show significant changes in weight (Omni = -0.6 ± 0.7kg, Vegan = 0.0 ± 0.5 kg), indicating a negative energy balance in the IF group, and neutral energy balance in the remaining two groups. There were no statistically significant differences in ratings of acceptability of the diets, although those in the IF group rated the diet as requiring less effort to maintain (median [range] = 6 [4-7] vs Omni = 3 [3-7] and Vegan = 4.5 [1-6]).
CONCLUSION:
Dietary acceptability was equal across all diets over a short-term intervention, with the addition of 2 fasting days per week having no significant impact on these outcomes. Furthermore, changes in weight indicated that the intended energy balance was achieved over this 2-week period. These results indicate that controlling energy and protein intake via provided food is equally acceptable to participants across the three diets studied when pre-packaged food was provided, and effective for controlling participant weight over a short-term intervention.