In 8 of the pairs of twins, the obese twin was as 'metabolically healthy' as his or her lean co-twin, while in the other 8 pairs, the obese twin had a poorer blood fat profile, higher liver fat and increased insulin production and resistance, and higher blood pressure -- all hallmarks of unhealthy obesity that can lead to diabetes, heart problems and other complications.
The study is by Dr Kirsi Pietiläinen, Dr Jussi Naukkarinen and colleagues from the Obesity Research Unit, University of Helsinki, Helsinki, Finland, and is published in Diabetologia, the journal of the European Association for the Study of Diabetes (EASD).
Not all obese individuals display the metabolic disturbances commonly associated with excess fat accumulation. Mechanisms maintaining this 'metabolically healthy obesity' (MHO) are as yet unknown. In this new research, the authors studied different fat depots and transcriptional pathways in subcutaneous adipose tissue (SAT) of participants to analyse their relationship to the MHO phenomenon.
The sixteen rare young adult obesity-discordant identical (monozygotic) twin pairs (intra-pair difference in BMI ≥3kg/m2 and BMI range 20-40 and aged 23-36 years, were examined for detailed characteristics of metabolic health (subcutaneous-, intra-abdominal- and liver fat [magnetic resonance imaging (MRI)/ spectroscopy]), an oral glucose tolerance test (OGTT-to determine how quickly glucose is cleared from the blood), lipids, and certain markers of inflammation such as adipokines and C-reactive protein (CRP). The function of the mitochondria (part of the cell machinery) and inflammation in the SAT were also studied.
In all 16 pairs, the average weight difference between the obese co-twin and the lean-co-twin was 17kg. In half (8/16) of the pairs the obese co-twin had significantly higher liver fat (around 7 times higher), a 78% increase in insulin production during OGTT, increased CRP, significantly more disturbance in the blood fat profile and greater tendency for high blood pressure compared with the lean co-twin. In these obese co-twins, SAT expression of mitochondrial oxidative phosphorylation, branched-chain, amino acid catabolism, fatty acid oxidation and adipocyte differentiation pathways were downregulated and chronic inflammation upregulated, all of which are metabolic problems that can lead to complications and disease.
In the other eight pairs, the obese co-twin did not differ from the non-obese co-twin in liver fat, insulin sensitivity, CRP, lipids, blood pressure or SAT metabolic characteristics.
The authors discuss that it is also possible that the MHO stage will change with age or with advanced obesity. However, at present the two metabolically distinct groups were of the same age and had similar age of onset of obesity difference between the twin pair. They speculate: "Weight differences between the groups were similar, but a given weight difference may have different metabolic effects depending on where in the distribution of BMI a pair is located."
The authors conclude: "Our results suggest that maintenance of high mitochondrial transcription and lack of inflammation in SAT are associated with low liver fat and MHO...Future studies of the MHO phenotype may suggest new potentially drug targets -- with the most effective intervention point perhaps being improving mitochondrial function and prevention of inflammation in adipose tissue.
Dr. Jussi Naukkarinen | EurekAlert!
New study from the University of Halle: How climate change alters plant growth
12.01.2018 | Martin-Luther-Universität Halle-Wittenberg
Disarray in the brain
18.12.2017 | Universität zu Lübeck
What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...
For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.
Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...
At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.
No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...
Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.
Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...
The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...
08.01.2018 | Event News
11.12.2017 | Event News
08.12.2017 | Event News
17.01.2018 | Ecology, The Environment and Conservation
17.01.2018 | Physics and Astronomy
17.01.2018 | Awards Funding