Faculty of Health, Medicine and Life Sciences (FHML)
Bachelor Health Sciences
Submission deadline: 03-07-2020
Obesity, insulin resistance and muscle atrophy are closely correlated via interorgan cross talk.
Obesity can be seen as a growing burden in various areas. It leads to higher healthcare costs, higher
risk of mortality and decreased life quality. Obesity is not only linked with social and economic
effects, but also with other diseases. Obesity is closely related to diabetes mellitus type 2,
hypertension, fatty liver disease, several cancers, insulin resistance and cardiovascular diseases. In
obesity, a higher fat storage in the adipocytes leads to the swelling of these adipocytes. Adipose
tissue not only serves as a storage place, but also secretes adipokines. The secretion profile of
adipokines is changed in obesity, which eventually leads to the development of insulin resistance.
Adiponectin, vaspin and leptin play an important role in the protection against insulin resistance.
More evidence is needed to explain the opposite effects of IL-6 on insulin resistance. Less evidence is
available about the link between obesity and muscle atrophy. However, there are indications that
this link also can be explained by interorgan cross talk. In an obese state, the adipokine secretion
profile can change which negatively affects the skeletal muscle which leads to muscle breakdown and
eventually muscle atrophy. Myotubes from elderly individuals stimulated by obese adipose
conditioned are thinner than myotubes stimulated by normal weight adipose conditioned mediums.
In conclusion, a changed adipokine secretion profile leads to inflammation which leads to
degradation of proteins and eventually leads to muscle atrophy.
Obesity is a worldwide, complicated chronic disease identified by disproportionate fat accumulation
that deteriorates health1. Individuals are diagnosed with obesity when they have a Body Mass Index
of 30 kg/m2 or higher. Obesity can be caused by a combination of genetic, psychosocial,
environmental and behavioral factors2. Additional research is needed to understand the relation
between these genetic and environmental aspects. However, research shows that an energy
imbalance is the most presumable environmental factor for developing obesity3. This energy
imbalance is caused by a continued increase in daily energy intake which cannot be compensated by
an identical energy expenditure due to an increase in physical inactivity. The excessive energy intake
is due to a surplus intake of simple carbohydrates and fats. The environmental influence is the most
common risk factor for developing obesity. An increased prevalence rate of obesity has become a
worldwide health problem among both adults and children4. Between 1975 and 2016 the worldwide
prevalence rate of obesity increased from 4% to over 18% for both adults and children. In 2016 more
than 650 million adults worldwide were obese, which comes down to 13% of the adult world
population5. Not only the increasing prevalence rates are a growing problem, obesity also occurs
more often at a younger age6.
Obesity is a worldwide health problem since it leads to adverse outcomes such as higher
direct and indirect healthcare costs, the increase of premature mortality and the decline of life
quality and life expectancy7. Several studies from the United States, Sweden and Australia show that
individuals with a BMI between 40 and 44.9 and a BMI between 55 and 59.9, lost respectively 6.5
years and 13.7 years of life expectancy8. This disease not only has economic and social effects, but it
is also linked to several other diseases. Obesity has shown to increase the risk of developing diabetes
mellitus type 2, hypertension, fatty liver disease, several cancers, stroke, dementia, insulin resistance
and cardiovascular diseases5, 9. In some studies there are indications that obesity also has a strong
link with muscle atrophy, however little research has been devoted to this subject. Several
indications show that this link can be explained by inter organ cross talk. Adipose tissue secretes
adipokines which can influence other organs. In particular, adipokines produced during the state of
obesity may negatively influence the muscles, which leads to muscle breakdown and eventually to
muscle atrophy10. The prevalence of obesity in combination with sarcopenia, the decline of muscle
mass and strength or function related to age, has increased for adults aged 65 years and older10. For
this reason, the combination between obesity and sarcopenia is becoming an increasingly dangerous
problem since sarcopenia leads to enormous social and personal costs, physical disability, lowered
quality of life and even death11.