The high worldwide prevalence of overweight and obesity as well as metabolic and disease consequences, are well-documented. The positive energy balance underlying obesity is attributable to excess energy intake and/or insufficient energy expenditure. However, it seems that the increase in mean body weight can be sufficiently explained by increases in mean energy intake. It has been proposed that this overeating is partly caused by increased availability of highly processed energy dense, high reward foods. Psychosocial stress and sleep insufficiency is pervasive in industrialized societies. A growing body of evidence suggests stress to be involved in obesity, although it is unknown whether stress is a cause or consequence. Stress affecting dietary intake; skewing intake towards greater consumption of highly palatable energy dense foods, also referred to as high reward foods. A causal relationship between stress and reward seeking behavior is supported by findings from animal studies reporting rewarding behavior by consumption of sweet tasting food in response to a stressor.

Our aim is to investigate differences in purchases of particular food-items in free living individuals, during a stressful (upcoming exam) and non-stressful (no upcoming exam) period.

Hypothesis: Participants will purchase more high reward foods during the pre-exam period, compared to the control non-exam period.

STUDY METHODS

Study design:

The study is a randomized controlled two-armed cross-over intervention study. The study is carried out in 50 healthy university students, both genders. In random order the participants will be investigated during stressful-period (prior to an exam) and a non-stressful (control period) period. Each participant will take part in all together four visits, two in the stressful period and two visits in the non-stressful period.

The study will take place, at the Department of Nutrition, Exercise and Sports (NEXS), Faculty of Science at the University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C. Recruitment will take place at the University of Copenhagen

STATISTICAL ANALYSES Analysis of the primary outcome (food choices) will be based on an ANCOVA-type linear mixed model with the intervention and allocation order as the fixed effect and person as the random effect. Analysis will be performed using the software R, SAS, STATA or SPSS. Analyses, data processing and writing of the article are expected to extend over the study period and a year beyond.

Inclusion Criteria:

• Healthy, weight stabile (defined as no weight gain/loss >3 kg during the past three months) students at the University of Copenhagen
• Age > 18 years, men and women

Exclusion Criteria:

• Purposefully seeking to lose or gain weight
• Diabetes.
• Blood donation < 1 week prior to the study and during the study
• Lactation, Pregnancy or planning of pregnancy during the study
• Inability, physically or mentally, to comply with the procedures required by the study- protocol, as evaluated by the investigator
• Participation in other clinical trials during the study
• Diagnosed with stress
• Daily use of medication influencing biomarkers of stress