Differences in Eating Frequency Between Vegan and Omnivorous Diets

In several randomized controlled trials comparing vegan or vegetarian diets to omnivorous dietary approaches, significant weight loss has occurred in the absence of significantly different changes in reported energy intake between groups. This is different than what is seen in studies using traditional weight loss diets (reduced energy omnivorous diets), which demonstrate a greater reduction in energy intake corresponding to greater weight loss. In observational cohort studies, among Adventist Health Study-2 participants following five different diets, BMI was found to be lowest among vegans and highest among omnivores; yet energy intake did not significantly differ among the five groups, averaging 2,000 kcals/day, with the exception of lower energy intake among semi-vegetarians.

This difference in body weight without observed differences in energy intake could possibly be explained by higher levels of physical activity among vegan and vegetarian participants, which have been observed in some of the cohort studies. Physical activity, however, was controlled for in the randomized trials either giving participants identical exercise recommendations, or holding exercise levels constant across experimental groups.

This present study will utilize the Bite Counter to estimate the differences between calories consumed between a vegan diet and an omnivore diet. The significance of using the Bite Counter is that it is a simple way to estimate energy intake. While there are many devices that measure energy expenditure (e.g. various exercise scales and equipment), there are few devices that account for energy intake. Traditional methods of estimating energy intake tend to utilize dietary recalls, but these procedures require much more effort and do not provide real time feedback like the Bite Counter does. Therefore, this study will contribute to current research by capturing data on dietary differences between vegans and omnivores, as well as assessing the usability of this device for dietary self-monitoring. The study will also use an objective physical activity and sleep tracker (the MisFit) to examine differences in exercise and sleeping between omnivorous and vegan participants.

Inclusion criteria

• Participants must be adults (18 years and older) that are weight stable individuals (having a BMI between 18.5 - 25
• Participants must have been following their chosen diet for at least the past 6 months
• Participants must be willing to wear a wrist-worn device to track their food intake and physical activity

Exclusion criteria

• Participants should have not experienced weight loss or gain ±10 lbs over the past 6 months) and they must not be on a weight loss diet