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Effects of diet intervention on body composition and ectopic fat accumulation in obese postmenopausal women
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Medicine.
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Background Obesity is increasing worldwide and is a major contributor to morbidity and mortality. Notably, abdominal (central) obesity carries a high risk of obesity-related diseases, while peripheral fat accumulation can act in a protective manner. A redistribution of fat from peripheral to central depots is seen after the menopause and is associated with an increasing prevalence of diabetes and cardiovascular disease. A key mediator may be ectopic fat accumulation in the liver. Our hypothesis was that a Palaeolithic-type diet (PD) consumed ad libitum improves body composition and metabolic risk markers, including liver fat and insulin sensitivity, in obese postmenopausal women.

Methods In study I the study subjects (n=10) used a PD during 5 weeks. In study II and III (n=70) the effect of a Palaeolithic-type diet (PD) was compared to a diet according to the Nordic Nutrition Recommendations diet (NNR) during a 2-year randomized clinical trial (RCT). Food records and nitrogen excretion in urine validated food intake. Anthropometric measurements were performed in a standardized manner. Body composition was calculated using Dual Energy X-ray Absorptiometry (DXA). Total energy expenditure was calculated by accelerometry (Actiheart®) in combination with indirect calorimetry. Liver and muscle fat content was estimated by magnet resonance spectroscopy (1H-MRS). Insulin sensitivity was measured either with hyperinsulinemic euglycemic clamps (paper I) or oral glucose tolerance tests (OGTTs) (paper III).

Results In study I a significant weight loss, linked to improved lipid and blood pressure levels, was associated with a 49% decrease in liver fat. Concomitantly, hepatic insulin sensitivity improved, while peripheral insulin sensitivity (and muscle fat) was unaltered. In study II/III both groups had a significant and sustained weight loss after 2 years. The PD was more effective than the NNR diet regarding loss of weight and fat mass after 6 months, but not after 24 months. Serum triglyceride levels were significantly lower at 24 months in the PD group. Liver fat decreased throughout the study in both groups. Hepatic insulin sensitivity improved during the first 6 months of the study, while peripheral insulin sensitivity did not change. Hepatic insulin sensitivity was associated with liver fat at baseline, but not during the diet intervention. Energy expenditure did not change in any of the study groups.

Conclusion Ad libitum diets can have sustained beneficial effects on weight and body composition in obese postmenopausal women, a PD being more effective on short-term than a diet according to the NNR. This is associated with a reduction in liver fat that may reduce the risk of future diabetes and cardiovascular disease. Further studies are needed in order to explore the association between liver fat and metabolic dysfunction, including insulin sensitivity.

Place, publisher, year, edition, pages
Umeå: Umeå universitet , 2014. , 45 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1682
Keyword [en]
obesity, diet intervention, postmenopausal, ectopic fat
National Category
Clinical Medicine
Research subject
Medicine
Identifiers
URN: urn:nbn:se:umu:diva-95161ISBN: 978-91-7601-159-1 (print)OAI: oai:DiVA.org:umu-95161DiVA: diva2:757793
Public defence
2014-11-14, Hörsal B, byggnad 1D, Umeå universitet, Umeå, 13:00 (Swedish)
Opponent
Supervisors
Available from: 2014-10-24 Created: 2014-10-23 Last updated: 2015-08-14Bibliographically approved
List of papers
1. A Palaeolithic-type diet causes strong tissue-specific effects on ectopic fat deposition in obese postmenopausal women
Open this publication in new window or tab >>A Palaeolithic-type diet causes strong tissue-specific effects on ectopic fat deposition in obese postmenopausal women
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2013 (English)In: Journal of Internal Medicine, ISSN 0954-6820, E-ISSN 1365-2796, Vol. 274, no 1, 67-76 p.Article in journal (Refereed) Published
Abstract [en]

OBJECTIVES: Ectopic fat accumulation in liver and skeletal muscle may be an essential link between abdominal obesity, insulin resistance and increased risk of cardiovascular disease after menopause. We hypothesized that a diet containing a relatively high content of protein and unsaturated fat [mainly monounsaturated fatty acids (MUFAs)] but limited carbohydrates and saturated fat would reduce lipid content in liver and muscle and increase insulin sensitivity in postmenopausal women.

SUBJECTS: Ten healthy, nonsmoking postmenopausal women with a body mass index (BMI) >27 (28-35) kg m-2 were included in the study.

INTERVENTIONS: Participants were instructed to consume an ad libitum Palaeolithic-type diet intended to provide approximately 30 energy percentage (E%) protein, 40 E% fat (mainly MUFAs) and 30 E% carbohydrate. Intramyocellular lipid (IMCL) levels in calf muscles and liver triglyceride levels were quantified using proton magnetic resonance spectroscopy (1 H-MRS) before and 5 weeks after dietary intervention. Insulin sensitivity was estimated by homoeostasis model assessment (HOMA) indices and the euglycaemic hyperinsulinaemic clamp technique.

RESULTS: Mean energy intake decreased by 25% with a weight loss of 4.5 kg. BMI, waist and hip circumference, waist/hip ratio and abdominal sagittal diameter also decreased significantly, as did diastolic blood pressure (mean -7 mmHg), levels of fasting serum glucose, cholesterol, triglycerides, LDL/HDL cholesterol, apolipoprotein B (ApoB) and apolipoprotein A1 (ApoA1), urinary C-peptide and HOMA indices. Whole-body insulin sensitivity did not change. Liver triglyceride levels decreased by 49%, whereas IMCL levels in skeletal muscle were not significantly altered.

CONCLUSIONS: A modified Palaeolithic-type diet has strong and tissue-specific effects on ectopic lipid deposition in postmenopausal women.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2013
Keyword
adipose tissue, diet, fatty liver, insulin resistance, postmenopausal, weight
National Category
Environmental Health and Occupational Health Nutrition and Dietetics
Research subject
Food and Nutrition
Identifiers
urn:nbn:se:umu:diva-67135 (URN)10.1111/joim.12048 (DOI)000320279000005 ()23414424 (PubMedID)
Available from: 2013-03-14 Created: 2013-03-14 Last updated: 2017-12-06Bibliographically approved
2. Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial
Open this publication in new window or tab >>Long-term effects of a Palaeolithic-type diet in obese postmenopausal women: a 2-year randomized trial
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2014 (English)In: European Journal of Clinical Nutrition, ISSN 0954-3007, E-ISSN 1476-5640, Vol. 68, no 3, 350-7 p.Article in journal (Refereed) Published
Abstract [en]

Background/Objectives: Short-term studies have suggested beneficial effects of a Palaeolithic-type diet (PD) on body weight and metabolic balance. We now report the long-term effects of a PD on anthropometric measurements and metabolic balance in obese postmenopausal women, in comparison with a diet according to the Nordic Nutrition Recommendations (NNR).

Subjects/Methods: Seventy obese postmenopausal women (mean age 60 years, body mass index 33 kg/m(2)) were assigned to an ad libitum PD or NNR diet in a 2-year randomized controlled trial. The primary outcome was change in fat mass as measured by dual-energy X-ray absorptiometry.

Results: Both groups significantly decreased total fat mass at 6 months (-6.5 and-2.6 kg) and 24 months (-4.6 and-2.9 kg), with a more pronounced fat loss in the PD group at 6 months (P<0.001) but not at 24 months (P=0.095). Waist circumference and sagittal diameter also decreased in both the groups, with a more pronounced decrease in the PD group at 6 months (-11.1 vs-5.8 cm, P=0.001 and-3.7 vs-2.0 cm, P<0.001, respectively). Triglyceride levels decreased significantly more at 6 and 24 months in the PD group than in the NNR group (P<0.001 and P=0.004). Nitrogen excretion did not differ between the groups.

Conclusions: A PD has greater beneficial effects vs an NNR diet regarding fat mass, abdominal obesity and triglyceride levels in obese postmenopausal women; effects not sustained for anthropometric measurements at 24 months. Adherence to protein intake was poor in the PD group. The long-term consequences of these changes remain to be studied.

Place, publisher, year, edition, pages
Nature Publishing Group, 2014
Keyword
adipose tissue, diet, insulin resistance, postmenopausal, weight
National Category
Nutrition and Dietetics Public Health, Global Health, Social Medicine and Epidemiology
Identifiers
urn:nbn:se:umu:diva-86275 (URN)10.1038/ejcn.2013.290 (DOI)000332634300011 ()24473459 (PubMedID)
Note

C. Mellberg, S. Sandberg and M. Ryberg share first authorship.

T. Olsson and B. Lindahl share senior authorship.

Available from: 2014-02-21 Created: 2014-02-21 Last updated: 2017-12-05Bibliographically approved
3. Decreased liver fat during a two-year diet intervention was not associated with improvement in hepatic insulin sensitivity
Open this publication in new window or tab >>Decreased liver fat during a two-year diet intervention was not associated with improvement in hepatic insulin sensitivity
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(English)Manuscript (preprint) (Other academic)
National Category
Nutrition and Dietetics
Identifiers
urn:nbn:se:umu:diva-95211 (URN)
Available from: 2014-10-24 Created: 2014-10-24 Last updated: 2014-10-27Bibliographically approved

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