Physical Inactivity and Appetite Regulation

The Effects of Inactivity on GLP-1 Stimulated Appetite Regulation in Healthy Normal Weight Males: A Randomised, Parallel Group Study

The goal of this parallel-group, two-arm, assessor-blinded, randomised clinical trial is to investigate the effects of reducing physical activity on food intake and satiety in physically active and healthy males, 40-55 years of age.

The main questions it aims to answer are:

• Does physical inactivity affect GLP-1 stimulated food intake?
• Does physical inactivity affect food preferences, satiety and other mechanisms supporting appetite regulation?

Participants will be randomised (1:1) to two weeks of either no intervention (control group) or inactivity. Inactivity will be implemented as cessation of active commuting and all other structured exercise. Furthermore, steps will be reduced to a maximum of 1500 steps/day.

Researchers will compare the inactivity group to the control group to see if physical inactivity impairs appetite regulation.

To contextualize the changes in ad libitum food intake driven by two weeks of physical inactivity, a sub-study will assess the effect of GLP-1 infusion on ad libitum food intake compared with a saline control in 20 participants included based on same eligibility criteria as in the main study. The estimated GLP-1 induced change in ad libitum food intake will be descriptively compared to the estimated GLP-1 + inactivity induced change in ad libitum food intake (main-study) to provide context for any attenuation in appetite suppression observed in the main-study. Outcomes related to subjective appetite measures (hunger, satiety, and food preference) will also be assessed in this way.

The primary hypothesis is that GLP-1 infusion will suppress appetite and reduce ad libitum food intake compared with saline control. The secondary hypothesis is that GLP-1 infusion will diminish subjective feelings of hunger and increase satiety.

Inclusion Criteria:

1. Male
2. Age ≥ 40 years and ≤ 55 years
3. Body mass index (BMI) > 20 and < 25 kg/m2
4. Physical activity level should as a minimum include: Active commuting by biking a minimum of 10 km, four days per week or an equivalent amount of other physical activity four days per week.
5. Healthy (based on self-reporting, pre-study medical examination and biochemical screening)
6. Can adhere to two weeks of inactivity (refrain from running, cycling and all other exercise while reducing steps to max. 1500 pr. day)
7. Caucasian
8. No change in body weight > 5 kg within the last 6 months
9. Eats breakfast and lunch daily
10. Does not follow specific dietary restrictions
11. No disliking of spaghetti bolognese
12. No diagnosis of psychiatric disorder or treatment with anti-depressant or anti-psychotic medication
13. No history of suicidal behavior or ideations.
14. No previous surgical treatment for obesity
15. No cardiovascular disease
16. No rheumatologic disease
17. No metabolic/endocrine disease
18. No liver disease (ASAT or ALAT >2x upper normal range)
19. No other chronic disease
20. No elite sports
21. No frequent or chronic use of medications affecting bodyweight, physical performance, or inflammation (NSAIDS, DMARDS, corticosteroids)
22. No current infection
23. No history of cancer
24. No anemia (hematocrit <33%)
25. No smoking
26. No participation in other research intervention studies

Exclusion Criteria:

1. Clinical or biochemical signs of disease
2. HbA1c > 39 mmol/mol
3. Unable to allocate the needed time to fulfill the intervention
4. Language barrier, mental incapacity, unwillingness, or inability to understand and be able to complete the interventions