The effect of time-restricted feeding on glycemic biomarkers : A literature study

Abstract: Background: The prevalence of diabetes and obesity has been on the rise for many years and the search for new and effective dietetic solutions aiming at reducing calories, reducing body mass and improving diabetes has been ongoing. Currently, the intermittent fasting diet - the practice of alternating periods of eating and fasting - is gaining popularity. One of them is Time-restricted feeding (TRF), which time-limits energy intake within a defined window of time up to 10 hours per day without necessarily altering diet quality or quantity. A reduction in calorie intake, bodyweight, blood pressure, oxidative stress, inflammation biomarkers and triglycerides are evident with TRF studies conducted so far. Aim: The aim of the thesis is to investigate the effects of time-restricted feeding on glycemic biomarkers in human studies. Methods: A literature study is conducted with six chosen experimental studies which are primarily randomized controlled trials or randomized crossover trials with a TRF window of maximum 10 hours per day and predominantly with participants with overweight/obesity, prediabetes, type 2 diabetes and metabolic syndrome. Results: Compared to either baseline and/or control group, fasting glucose was reduced in 3 out of 6 TRF studies, while fasting insulin was reduced in 3 out of 5 TRF studies and HbA1C was decreased in 1 out of 2 TRF studies. For postprandial response, 1 out of 2 TRF studies found a reduction in glucose and likewise for insulin. Mean glucose levels were reduced in 1 out of 3 TRF studies. Insulin resistance was reduced in 3 out of 4 TRF studies while insulin sensitivity was reduced in the one study measuring this. Beta cell function improved in 2 out of 2 TRF studies compared to the control group or baseline. Conclusion: There are indications that TRF has an effect on glycemic biomarkers and thus potentially being able to reduce the risk and/or improve the treatment of type 2 diabetes. But in order to give a more definite answer more studies need to be conducted. In general, these studies should preferably have more participants and be methodologically stronger when it e.g. comes to the control of the dietary regimen.