WAT is the abbreviation for “White Adipose
Tissue”. Those of you who read last week’s article may remember that
researchers have been investigating WAT and BAT (Brown Adipose Tissue) for more
than a decade. They have come to the conclusion that both types of body fat are
not just heaps of inactive lard, but highly active metabolic powerhouses that
drive many different body processes.
According to Prof Alta Schutte who
delivered a paper on Adipose Tissue: A
Fascinating Endocrine Organ at the CNE Event presented by Nutritional
Solutions in April 2015, “WAT secretes more than 600 bioactive factors
These adipokines are involved with the regulation of
appetite, satiety (feeling of fullness) and activity, which all impact on body
weight. However, the adipokines produced by WAT also influence other body
functions. For example, WAT adipokines play a major role in the condition of
chronic low grade inflammation that is a feature of obesity. This inflammation
in turn influences adipokines that stimulate diabetic, inflammatory and
to promote formation of fatty deposits in arteries) processes in the body.
Read: Diet & your brain: appetite
Adipokines are also implicated in high
blood pressure, they exert an influence on the skeleton and bone cartilage, and
more recently, have even been linked to dementia.
To illustrate how versatile and divergent
these 600 bioactive compounds are, Prof Schutte described the roles and
functions of some of the factors.
For example, there is an adipokine called
“adiponectin” which has the following functions:
Adiponectin has protective functions. It
sensitises insulin, is anti-inflammatory, increases energy utilisation and
causes weight loss.
Read: Energy output
This is obviously an adipokine that bears
watching because adiponectin is currently regarded as a compound that may have
the greatest potential of all, to help humanity lose weight! Unfortunately
researchers know that adiponectin levels tend to drop as people gain weight.
Future obesity treatments may involve stimulation of adiponectin production in
WAT or use of adiponectin extracts to stimulate weight loss.
The most famous adipokine which we know a
lot about, is of course leptin. We now know that leptin is not a magic bullet
that can cure obesity by means of injecting leptin into obese individuals. The
reason for this is that obese individuals make large quantities of their own
leptin, but their body and brain cells do not react to the hormone. One could
say that the obese are “leptin resistant”, just as patients with type 2
diabetes are insulin resistant.
Read: Hormone tied to food fondness
Giving leptin-resistant patients even more
leptin is obviously not the way to go, so researchers are now trying to
pinpoint a “leptin sensitizing compound” to attempt to help body cells that are
resistant to leptin to recognise the hormone and react to it in the desired way
by promoting weight loss. This area of research will hopefully come up with a
solution to obesity in the not too distant future.
Grehlin is not an adipokine because it is
not produced by fat tissue, but by the stomach. However, Prof Schutte included
this hormone in her talk because it is so often also implicated in weight gain
Grehlin levels increase when people feel
hungry and grehlin is then responsible for increased food intake, which can
lead to weight gain. However, researchers have discovered that patients with
anorexia nervosa have extremely high grehlin levels, which seems to indicate
that not all grehlin production automatically leads to weight gain.
Read: Why some still eat when full
Prof Schutte reported that in the South
African POWIRS-Study (Profiles of Obese Women with the Insulin Resistance
Syndrome) which compared a variety of metabolic factors, including grehlin, in
young and older women who were lean, overweight or obese, found that in young
women grehlin levels decreased as overweight or obesity increased. This
association was not identified in the older women.
The relationship between grehlin and
leptin has been called a “yin-yang” relationship which may be responsible for
maintaining the energy reserves we need to function adequately and the amount
of food we ingest, but a great deal of research still needs to be done before
we will know if one or both of these “new” hormones determines obesity and if
they can be manipulated to induce weight loss.
What is very evident, is that the world of
adipokines is highly complex and that at present we do not know enough to use
them as pharmaceuticals (e.g. injections etc.), something many slimming clinics
pretend to do.
The most positive results obtained so far
indicate that when people exercised and reduced their energy intake by adjusting
their diets, it had a positive effect on leptin function. In contrast, the
control subjects who made no changes to their lifestyles, lost their
adiponectin protection (e.g. insulin sensitisation, anti-inflammatory action,
increased energy use and weight loss), which is regarded as a very negative
Read: The Anti-Inflammatory Diet
Prof Schutte emphasised that the advice
which dieticians have been giving overweight patients for many years, namely to
exercise and reduce dietary energy intake, will also improve the production and
function of adipokines and thus help patients to achieve successful weight
While we wait for research to unveil the
secrets of WAT and BAT and the many different hormones these two types of fat
produce, the most sensible advice to anyone who is overweight is: “Increase
your energy output with exercise and reduce your energy intake by using an
energy-reduced, balanced diet.”
Chemicals that control appetite
Inflammation key to obesity ills
Leptin - the answer to obesity?
- Schutte A (2015). Adipose Tissue: A
Fascinating Endocrine Organ. Paper presented at the Nutritional Solutions CNE
Event, 16 April 2015, Johannesburg.
- Schutte AE et al (2007). Ageing influences
the level and functions of fasting plasma grehlin levels: The POWIRS- Study. Regulatory
Image: Body fat from Shutterstock
Dr Ingrid van Heerden is a registered dietician and holds a doctoral degree in Nutrition and Biochemistry. She believes that "we are what we eat" and offers free nutrition and weight loss advice via her DietDoc service on Health24.com. Read more of her articles.