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Nachrichten, Termine, Experten
Nachrichten, Termine, Experten
Whether we tend to eat carbohydrates or fats in the morning may help determine how our metabolism works. Prof. Olga Ramich from the German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) and Charité – Universitätsmedizin Berlin and her team have now, for the first time in humans, shown that the temporal distribution of carbohydrate and fat intake changes the activity of more than a thousand genes in adipose tissue throughout the day – including genes that regulate carbohydrate and fat metabolism as well as inflammatory processes. The results were published in the journal Food Research International.
Human metabolism is regulated by internal clocks and show the so-called circadian rhythms. Many processes, such as sugar uptake, fat burning, or hormone release, oscillate during the day, i.e., they fluctuate and exhibit characteristic 24-hour rhythms. If nutrients are consumed outside the optimal time windows for the internal rhythms, this could promote metabolic disorders in the long term. The field of chrononutrition investigates the underlying molecular mechanisms to optimize eating times and increase metabolic health, ultimately aiming to prevent chronic diseases.
Fats for Breakfast or Dinner?
Prof. Olga Ramich, and her team at the German Institute of Human Nutrition Potsdam-Rehbruecke (DIfE) have conducted a pioneering study in humans to explore whether the time of day when carbohydrates and fats are consumed affects gene expression in subcutaneous fat tissue, regardless of calorie intake. The research, based on data from a controlled dietary study with a crossover design involving 29 overweight men without diabetes. Participants followed two different eating plans, carefully matched for calorie content, for four weeks each.
One plan prioritized carbohydrate in the morning and fat in the evening, while the other reversed this pattern. This design allowed researchers to isolate individual metabolic responses more effectively.
The team collected tissue samples from the participants' subcutaneous adipose tissue at three different times throughout the investigation day, before and after each dietary intervention. The researchers analyzed the transcriptome of these samples, a dynamic snapshot of gene activity, in cooperation with Prof. Achim Kramer, Head of the Research Area Chronobiology at the Department of Anesthesiology and Intensive Care Medicine at Charité.
Clear Differences in Adipose Tissue
For the first time, Ramich and her team characterized the gene rhythms in subcutaneous adipose tissue and demonstrated that the temporal distribution of nutrients across the day alters the oscillating and non-oscillating transcriptome.
The analyses showed that 1,386 genes in the examined adipose tissue are subject to diurnal oscillations. Many of these genes are associated with glucose and fat metabolism, or with inflammatory processes. The researchers found that the timing of macronutrient intake influenced the diurnal gene expression of nearly one-third of the oscillating genes in adipose tissue. Some oscillating genes exhibited altered rhythm parameters, others ceased oscillation, or, conversely, non-rhythmic genes became rhythmic.
Consuming a fat-rich diet in the morning and a carbohydrate-rich diet in the evening led to an improvement in markers of insulin sensitivity in the examined adipose tissue. Shifting fat intake to the evening, however, increased the activity of inflammatory genes. This could be an indication of an early pro-inflammatory state in adipose tissue, which is considered a risk factor for the development of metabolic diseases such as obesity and type 2 diabetes.
A New Approach to Prevention
"Our results confirm initial findings that shifting macronutrient distribution throughout the day measurably influences metabolic processes in adipose tissue," says Ramich. "Late, fat-rich meals may trigger unfavorable molecular processes that could promote inflammation and metabolic problems in the long term."
The researchers see their findings as new avenues for preventing overweight and type 2 diabetes. "In addition to calorie intake and nutrient composition, meal timing could become an important component of personalized dietary recommendations in the future," explains Ramich.
However, the scientists emphasize that larger and long-term intervention studies are needed to derive health effects or recommendations for different populations, such as women and/or people with diabetes. Mechanistic studies in cell culture or animal models could also help to more closely examine the relationship between circadian changes in adipose tissue and overall metabolism.
Background Information
Study Design
In the controlled crossover study, overweight, non-obese men without diabetes were randomly assigned to two isocaloric, four-week diets: (1) a carbohydrate-rich diet (65 energy percent [EN%] carbohydrates, 20 EN% fat, and 15 EN% protein) with meals consumed between 6:00 AM and 1:30 PM, and a fat-rich diet (35 EN% carbohydrates, 50 EN% fat, and 15 EN% protein) with meals consumed between 4:30 PM and 10:00 PM, compared to (2) the reversed meal schedule.
Within each diet, energy intake was evenly distributed across the morning and afternoon. Following the four-week interventions were 12-hour testing days with carbohydrate-rich and fat-rich meal tolerance tests. Fat biopsies were taken three times during the testing day – morning, afternoon, and evening.
Transcriptom
The complete set of transcripts (RNA molecules) in a cell at a specific point in time. The transcriptome encompasses both coding and non-coding RNAs. Unlike the static genome (DNA), it provides a dynamic picture of active gene expression.
Prof. Dr. Olga Ramich
Heisenberg professorship at the Charité and the DIfE Head of the Department of Molecular Metabolism and Precision Nutrition at DIfE
phone: +49 33 200 88 - 2749
e-mail: olga.ramich@dife.de
Soliz-Rueda, J. R., Kessler, K., Jürchott, K., Sticht, C., Hornemann, S., Kramer, A., Pfeiffer, A. F. H., Pivovarova-Ramich, O.: Remodeling of human diurnal adipose tissue transcriptome by the composition of morning and afternoon meals. Food Res. Int. 231(1), 118685 (2026). [Open Access]
https://doi.org/10.1016/j.foodres.2026.118685
https://www.dife.de/en/news/press-releases/details-press-releases/nutrient-timin...
Nutrition can influence various parameters of rhythmic gene expression in tissues.
Source: Carolin Schrandt
Copyright: DIfE
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Nutrition can influence various parameters of rhythmic gene expression in tissues.
Source: Carolin Schrandt
Copyright: DIfE
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