Body clock and hormone responses can be changed by what and how much you eat.
Researchers in Germany have reported the findings of a study into how diet can impact on how hormones control fat and sugar levels in the body at different times of day.
As part of the study researchers at Helmholtz Zentrum München in Munich and the German Centre for Diabetes Research found that the metabolic cycle can be altered by a diet high in calories.
The results of the study, published in Molecular Cell, showed how glucocorticoid hormones, such as cortisol, can control sugar and fat levels differently during day and night, feeding and fasting, rest and activity, over the course of 24 hours.
Glucocorticoids are a group of natural and synthetic steroid hormones and are used widely in medicine as they can control the activity of the immune system.
However, they can also cause severe side effects by virtue of their ability to modulate sugar and fat metabolism, and side effects of being treated with glucocorticoids means a patient could be at risk of developing obesity, hypertriglyceridemia, fatty liver, hypertension or type 2 diabetes.
Researchers also studied the biological function of daily rhythms of hormone secretion (high before awakening and feeding, low when sleeping and fasting) as well as daily cycles of sugar and fat storage or release by the liver.
Each cell in the human body is driven by an internal clock which follows the circadian rhythm of 24 hours.
It is synchronised with the natural cycle of day and night mainly by sunlight, but also through social habits.
In a healthy system, glucocorticoid stress hormones, are produced every morning by the adrenal gland.
Example of fatty liver courtesy of Helmholtz Zentrum München / Uhlenhaut
The secretion of glucocorticoid peaks before awakening, prompting the body to use fatty acids and sugar as sources of energy, and enabling us to start our daily activities.
When the circadian rhythm is disrupted (e.g. through shift work or jetlag) and/or when the glucocorticoid level alters (e.g. through Cushing syndrome or long-term clinical application), profound metabolic dysregulation can be caused – like obesity, type 2 diabetes, and fatty liver disease.
The study team wanted to understand the relevance of these daily peaks of stress hormone secretion, the impact of these hormones on our “internal clock” and their role for daily cycles of metabolism.
Researchers looked at the metabolic actions of glucocorticoids’ in the liver.
The findings showed how the majority of rhythmic gene activity is controlled by these hormones.
When this control is lost, blood levels of sugar and fat are affected. Researchers concluded that this could explain how the liver controls blood levels of sugar and fat differently during day and night.
Professor Henriette Uhlenhaut and Dr Fabiana Quagliarini courtesy of Helmholtz Zentrum München
Study author Dr Fabiana Quagliarini said: “It is the first time to show that diet can change hormonal and drug responses of metabolic tissues.”
Professor Henriette Uhlenhaut, who led the study, said: “Understanding how glucocorticoids control 24-hour-cycles of gene activity in the liver and consequently blood levels of sugar and fat, provides new insights into ‘Chronomedicine’ and the development of metabolic disease.
“We could describe a new link between lifestyle, hormones and physiology at the molecular level, suggesting that obese people may respond differently to daily hormone secretion or to glucocorticoid drugs. These mechanisms are the basis for the design of future therapeutic approaches.”