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VOLUME 13 NUMBER 2 • DECEMBER 2016
81
SA JOURNAL OF DIABETES & VASCULAR DISEASE
REVIEW
Once fat was fat and that was that: our changing
perspectives on adipose tissue
WF FERRIS, NJ CROWTHER
Correspondence to: WF Ferris
Division of Endocrinology, Department of Medicine, Faculty of Health
Sciences, University of Stellenbosch, South Africa
e-mail:
wferris@sun.ac.zaNJ Crowther
Department of Chemical Pathology, National Health Laboratory Services,
University of Witwatersrand Medical School, Johannesburg, South Africa
Previously published in
Cardiovasc J Afr
2011;
22
: 147–154
S Afr J Diabetes Vasc Dis
2016;
13
: 81–87
Abstract
Past civilisations saw excess body fat as a symbol of wealth
and prosperity as the general population struggled with
food shortages and famine. Nowadays it is recognised
that obesity is associated with co-morbidities such as
cardiovascular disease and diabetes. Our views on the
role of adipose tissue have also changed, from being
solely a passive energy store, to an important endocrine
organ that modulates metabolism, immunity and satiety.
The relationship between increased visceral adiposity and
obesity-relatedco-morbiditieshas lead to the recognition that
variation in fat distribution contributes to ethnic differences
in the prevalence of obesity-related diseases. Our current
negative view of adipose tissue may change with the use of
pluripotent adipose-derived stromal cells, which may lead
to future autologous stem cell therapies for bone, muscle,
cardiac and cartilage disorders. Here, we briefly review the
concepts that adipose tissue is an endocrine organ, that
differences in body fat distribution underline the aetiology
of obesity-related co-morbidities, and the use of adipose-
derived stem cells for future therapies.
Keywords:
adipocytes, obesity, cardiovascular disease, stem cells
A changing view of adiposity through the ages
The incidence of obesity and obesity-related co-morbidities has
risen dramatically in the last century. The latest global data shows
that in 2004 cardiovascular disease was the primary cause of death,
above infectious and parasitic diseases, with the majority of cases
attributed to an unhealthy lifestyle. This includes over-nutrition.
1
The increase in obesity has been accompanied by increased interest
in fat and an abundance of research investigating the link between
excessive adiposity and the associated pathologies. Currently there
are over 130 000 research articles on obesity cited on PubMed
and these publications show that our perception of the function
of fat mass has changed considerably since the first entry cited
from 1880. However, our knowledge of adiposity stretches back
far beyond the 19th century. Although it is not known whether
classical scholars recognised that adipose tissue is our major energy
store, they did observe that excessive adiposity has negative health
implications.
The Indian physician Sushruta (sixth century BCE) was probably
the first to document a relationship between obesity and
co-morbidities such as diabetes and heart disease. Not unlike
today, he recommended exercise to remedy conditions that had
arisen from a sedentary lifestyle and ‘pampering the belly’.
2
Later
in Europe, Hippocrates (460–377 BC) independently recognized
the relationship between body composition, exercise and health,
exemplified in his quote: ‘If we could give every individual the right
amount of nourishment and exercise, not too little and not too
much, we would have found the safest way to health’. In a time of
scant medical knowledge, his insight extended further, beyond his
contemporaries, to include the pathogenicity of obesity, in writing:
‘Repletion, carried to extremes, is perilous’ and ‘Corpulence is
not only a disease in itself, but the harbinger of others’. He then
subsequently noted that life expectancy was far shorter in the
obese compared to lean individuals.
3
Although the detrimental effects of obesity have therefore
long been known, in the intervening millennia since Sushruta and
Hippocrates, portliness was generally regarded as a symbol of
affluence. This was primarily due to periodic food shortages and
famine, which were only brought under control in the Western
world in the last century yet still ravish the developing world today.
This association between wealth and increased body mass was
often reflected in the art of European masters such as Rubens
(1577–1640) who depicted women with a full-bodied, hour-glass
shape; a shape which was associated with opulence and fertility.
4
By the 20th century, the use of intensive farming in conjunction
with the mechanisation of the food industry helped to eradicate
famine in the developed world. The increasing availability of highly
palatable, high-energy foods and decreased levels of physical
activity has led to an increasing imbalance between energy input
and expenditure in the general population. The consequence
of this is a burgeoning of portliness and obesity. This rise in the
prevalence of obesity is a global phenomenon, occurring in both
the developed and the developing worlds. Data from the USA
shows that in the period 1988–1994 the prevalence of obesity was
22.5%,
5
and rose to 32.2% in the period 2003–2004.
6
A meta-
analysis of studies measuring prevalence of obesity in west African
countries showed that the prevalence of obesity in urban areas
rose from 7.0% in 1990–1994 to 15.0% by 2000–2004.
7
Data
from China demonstrated that the prevalence of overweight and
obesity was 14.6% in 1992 and 21.8% in 2002.
8
Similar trends
have been reported around the world. The increasing prevalence
of obesity in the developing world is compounded by the cultural
view of obesity as being a positive attribute, signifying both health
and wealth. This is particularly so in African nations,
9
and is in stark
contrast to the Western ideal, as portrayed in the mass media, of
thin is beautiful!