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To investigate the metabolic effects of a low carbohydrate versus energy-matched standard diet in morbidly obese individuals with prediabetes awaiting bariatric surgery.
The metabolic benefits of calorie restriction in obese people with or without impaired glycaemia are well-established. The impact of diet composition, however, remains poorly understood. Hepatic lipid content strongly correlates with hepatic insulin resistance, which is a key feature of the pre-diabetic state. The investigators hypothesize that a low carbohydrate diet compared to an energy-matched standard diet in morbidly obese patients with prediabetes scheduled for bariatric surgery results in greater reduction in liver fat.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Study intervention | Experimental | Participants will follow an energy deficient (30% deficit) low carbohydrate diet (10% of carbohydrates) for minimum two weeks. |
|
| Control intervention | Active Comparator | Participants will follow an energy deficient (30% deficit) standard diet (50% of carbohydrates) for minimum two weeks. |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Low carbohydrate diet | Other | A energy deficient (30% deficit) low carbohydrate diet (10% of carbohydrates) |
|
| Measure | Description | Time Frame |
|---|---|---|
| Change from baseline in intrahepatic triglyceride content | The intrahepatic triglyceride content will be evaluated by magnetic resonance spectroscopy | 2 weeks |
| Measure | Description | Time Frame |
|---|---|---|
| Change from baseline in body weight | The body weight will be measured using a pre-defined person scale | 2 weeks |
| Change from baseline in liver size | The liver size will be evaluated by magnetic resonance imaging |
| Measure | Description | Time Frame |
|---|---|---|
| Change from baseline in plasma metabolome | Fasting serum sampling | 2 weeks |
| Change from baseline in plasma transcriptome | Fasting serum sampling |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Lia Bally, MD PhD | Inselspital, Bern University Hospital, University of Bern | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Division of Endocrinology, Diabetes and Clinical Nutrition, Bern University Hospital | Bern | 3010 | Switzerland |
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| ID | Term |
|---|---|
| D011236 | Prediabetic State |
| D009767 | Obesity, Morbid |
| ID | Term |
|---|---|
| D003920 | Diabetes Mellitus |
| D044882 | Glucose Metabolism Disorders |
| D008659 | Metabolic Diseases |
| D009750 | Nutritional and Metabolic Diseases |
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| ID | Term |
|---|---|
| D050528 | Diet, Carbohydrate-Restricted |
| ID | Term |
|---|---|
| D004035 | Diet Therapy |
| D044623 | Nutrition Therapy |
| D013812 | Therapeutics |
| D004032 | Diet |
| D009747 |
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Single-centre, randomized parallel study
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| Energy-matched standard diet | Other | Energy-matched (30% deficit) standard diet (50% of carbohydrates) |
|
| 2 weeks |
| Change from baseline in visceral adipose tissue | The adipose tissue content will be evaluated by magnetic resonance imaging | 2 weeks |
| Change from baseline in whole body fat mass | Fat mass will be evaluated by bioimpedance | 2 weeks |
| Change from baseline in insulin secretion | The insulin secretion will be evaluated during an oral glucose tolerance test using the oral minimal model | 2 weeks |
| Change from baseline in insulin sensitivity | The insulin sensitivity will be evaluated during an oral glucose tolerance test using the oral minimal model | 2 weeks |
| 2 weeks |
| Change from baseline in Fibroblast Growth Factor 21 | Plasma level | 2 weeks |
| Change from baseline in adipose tissue inflammation | Adipose tissue histology | 2 weeks |
| Change from baseline in gut microbiota composition | Distribution of the predominant bacterial phylotypes will be assessed after 16S rRNA amplicon sequencing and subsequent taxonomic classification | 2 weeks |
| Change from baseline levels of secondary bile acids | Faecal sampling | 2 weeks |
| Change in frequency of immune cells (T-, B-, NK-cells, monocytes, neutrophils) | Frequency of immune cells will be analysed using flowcytometry | 2 weeks |
| Change in immunometabolism of T-cells | Immunometabolism will be assessed by quantifying rates of oxygen consumption and glycolysis using metabolic flux analysis | 2 weeks |
| Occurrence of surgical complication | Occurrence of the following: anastomotic leak, infection, bleeding, deep venous thrombosis (based on medical records) | Day of surgery until 2 weeks post-surgery |
| Length of hospital stay | Based on medical records | Day of surgery until 2 weeks post-surgery |
| D004700 | Endocrine System Diseases |
| D009765 | Obesity |
| D050177 | Overweight |
| D044343 | Overnutrition |
| D009748 | Nutrition Disorders |
| D001835 | Body Weight |
| D012816 | Signs and Symptoms |
| D013568 | Pathological Conditions, Signs and Symptoms |
| Nutritional Physiological Phenomena |
| D000066888 | Diet, Food, and Nutrition |
| D010829 | Physiological Phenomena |