The investigators aim to understand whether the acute cortisol response to food differs between differently processed foods.

In this monocentric, randomized, cross-over, open-label study, 20 healthy volunteers will receive two differently processed meals of similar caloric content and composition. The study will primarily focus on changes in blood cortisol levels, but other metabolic parameters will also be compared.

Obesity is one of the most serious health problems of the 21st century, with ultra-processed diets being a major driver of the current obesity pandemic. Understanding how these diets affect body weight is critical to identifying new treatment targets. Current evidence suggests that the degree of food processing may affect cortisol secretion, a hormone that plays a key role in body weight regulation by increasing with acute food intake and promoting energy storage in adipose tissue. However, whether ultra-processed foods enhance cortisol response has not been thoroughly investigated.

Here, the investigators aim to understand the reaction of GCs in response to different processed foods in healthy volunteers. No medication will be used in this study.

Participants will be asked to refrain from strenuous physical activity and alcohol consumption for 24 hours prior to the study. They will fast for 12 hours before consuming a high-calorie, low-processed meal. After fasting again, participants will consume a high-calorie, ultra-processed meal on a second study day. The order of the meals is not fixed. The study will include a screening visit and two study visits.

Inclusion Criteria:

• Males aged 18 to 40 years
• BMI 18.5-29.9 kg/m2

Exclusion Criteria:

• Severe acute or chronic disease
• Lactose intolerance
• Severe food allergy
• Casual smoking (more than six cigarettes per day)
• Frequent, heavy alcohol consumption (more than 30g/day)
• Frequent, heavy caffeine consumption (more than 4 caffeinated drinks/day)
• Regular physical exercise (more than 4hrs per week)
• Shift work
• Previous enrollment in a clinical trial within the past two months
• Intake of any steroid-containing drugs, including topical steroids and inhalers, within four weeks of the study initiation
• Contradictions to undergo the investigated intervention
• Inability or unwillingness to provide informed consent

Since hormone fluctuations associated with the menstrual cycle may alter cortisol levels, women will not be included in the study. Although diversity will be reduced and the statements of the study cannot be applied to the female sex, these strict inclusion criteria allow an optimal homogeneity and increase statistical power.