Lack of recruitment - no eligible participants.

The use of non-nutritive sweeteners (NNS) in replacement of nutritive sweeteners (NS) could be a potential weight loss strategy as it may reduce energy intake. One concern with the replacement of NS with NNS is the risk of caloric compensation after consumption of NNS. Most studies have examined the effect of NNS foods and beverages on energy intake in the short-term (one-day or less), with results suggesting lack of compensation in the very short-term (less than one day), and then compensation, or over compensation, when the NNS products are consumed on one day with measures of energy intake taken over 1 to 2 days (Anton et al., 2010; Lavin et al., 1997; Overduin et al., 2016; Appleton et al., 2007; Piernas et al., 2013). Given these mixed results, it is still not clear if NNS foods and beverages are a beneficial strategy for decreasing energy intake. However most studies have been in lab-based settings, in which participants are consuming provided food at specific times. No study has reported on the effect of NNS foods or beverages consumed over several days and energy intake on these days when participants are in free-living situations.

Therefore, the purpose of this investigation is to evaluate how NNS beverage consumption affects energy intake in free-living situations over a span of three days. Through a 3x4 mixed design, participants will be randomized into one of three groups: NNS beverage, NS beverage, or carbonated water (control). Participants will be encouraged to go about their normal daily activities and not change any other aspect except for drink consumption. One baseline and three, 24-hour dietary recalls will be collected over the course of the study to analyze energy intake. The specific aim of this investigation is to determine if caloric compensation occurs during 3-day exposure to NNS beverages.

At the completion of the phone screen, eligible participants will be scheduled to come to the Healthy Eating and Activity Laboratory for the start of their baseline assessment.

The first session will occur the week prior to the test days. At this appointment, informed consent will be obtained, a demographic questionnaire completed, a beverage questionnaire (BEVQ-15) completed, and an appropriate time and preferred mode of contact (text message or e-mail) will be collected. Participant's height and weight will be collected through an electronic scale for weight and a stadiometer for height using standard procedures (Lohman, et al., 1988). Next, participants will be given the SenseWear armband. Participants will be instructed to start wearing the armband upon awakening on Monday morning and to wear the arm band on their upper right arm until going to sleep Monday night (wear time should be at least 10 hours per day). Participants will be instructed to continue wearing the armband, in an identical manner as on Monday, on Tuesday, Wednesday, and Thursday. Participants will be instructed to not alter their physical activity from their normal routine from Monday to Thursday.

Participants will be randomized to one of the three groups, Coke (NS), Diet Coke (NNS), or carbonated water (control) using a random numbers table. For this investigation, Coke and Diet Coke will be used due to Coke and Diet Coke ranked number one and two as the most popular beverages in the U.S. from 2010 to 2018 ("Sweet! America's top 10 brands of soda," 2011; "Top 10 Best Selling Soft Drink Brands in The World," 2016). Next, participants will receive twelve, 12-ounce cans of a beverage that represents their assigned condition. Participants will be instructed to drink their assigned beverages Tuesday through Thursday, and to consume one beverage at 12pm, the second at 3pm, and the third at 6pm. Participants will be instructed that the beverages need to be consumed within +/- 30 minutes of the instructed time. Participants will be instructed that any other beverage consumed on Tuesday through Thursday should be water. Next, instructions will be provided to participants on how to complete the 24-hour dietary recalls and a two-dimensional visual aid will be provided to help participants in estimating portion sizes. Participants will also be given a detailed schedule about their study participation.

Participants will be called on Tuesday, Wednesday, and Thursday to complete 24-hour dietary recalls. Participants will be sent daily reminders regarding their recalls and wearing the armband via text or e-mail (participant preferred mode of contact).

A final appointment will be completed on Friday in the HEAL lab. The armband will be returned and downloaded, the final recall will be completed, and participants will be debriefed about the purpose of the study. Participants will not be responsible for paying for the SenseWear Armband if they lose it or damage it. Once all data are collected, participants will be given a $25 gift card for their participation. If a participant cannot come to the lab on the Friday of their final appointment, then the last recall will be collected via phone and the appointment will be rescheduled in order to collect the armband.

Inclusion Criteria:

1. The eligible age range of participants will be 18-35 years. The age range for eligible participants was set because research has shown taste sensitivity declines after the age of 60. In 2001, Mojet and colleagues used sucrose and aspartame to test taste threshold sensitivity in young adults age 19-33 years and elderly adults age 60-75 years. Results showed a decrease in threshold and taste in the elderly adults (Mojet, et al., 2001). Sensitivity to the five basic tastes, sweet, salty, sour, bitter, and umami, begins to decline after the age of 60 ("Aging changes in the senses," n.d.).
2. Individuals with overweight or class I obesity - Body mass index (BMI) range 25-34.9 kg/m2
3. Does not participate in more than 100 minutes of structured, moderate- to high-intensity physical activity weekly
4. Consumes > 36oz of NS beverages daily as assessed by the Beverage Questionnaire (BEVQ)-15 (Hedrick, et al., 2012) - NS beverages include: 100% fruit juice, sweetened juice beverages, energy and sports drinks, sweetened tea or coffee, and soft drinks.
5. Willing to substitute NS beverages for NNS beverages or carbonated water for a three-day period
6. Able to complete all study days consecutively, with all study days following usual schedules and activities (i.e. not traveling)
7. Report a favorable preference for the beverages involved in the study, with participants rating each beverage item ≥3 on a 5-point Likert scale during the phone screen
8. Reports a usual wake up time of 10:00a.m or earlier on Mondays through Fridays.
9. Reports no known allergic reaction to metal

Exclusion Criteria:

1. Report of current dieting or dieting within the past month
2. Report of known reactions to sugar or NNS