11 May 2015

Body fat helps to regulate appetite and other processes

Diet Doc explains how body fat is not just a heap of inactive lard, but a highly active metabolic powerhouse that drives many different body processes.


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.

Active Fat

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 (adipokines).”

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 atherogenic (tending 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.

Specific adipokines

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 and loss.

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 result. 

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 loss.

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.”

Read more:

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 Peptides, 139:65-71.

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 Read more of her articles.


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