Middle-aged spread is the bane of many men and women of a certain age. Now, scientists say they are a step closer to understanding why it occurs. They believe it may lie with one of two types of fat in the body that becomes ‘less active with age’.
There is the more familiar white fat, which sits under the skin of the stomach and thighs and is the result of eating too much. Then there is brown fat – and its job is to generate heat. It does this by boosting the metabolism, so we start to use up the ‘bad’ white fat. It’s long been known that babies have brown fat around their shoulder blades to help them maintain their body temperature after birth.
But until recently it was thought this good fat disappeared in infancy because it was no longer needed. It’s since been shown that brown fat persists into adulthood and that women have more brown fat than men. Now, in a new study, Japanese scientists have discovered that as people age, the thermogenic activity – or heat production – in their brown fat reduces. This means it becomes less active and therefore burns less ‘bad’ white fat.
‘A common complaint is that older people have to work twice as hard with their diets and exercise to get half of the results of younger people,’ said Dr Gerald Weissmann, Editor-in-Chief of The FASEB Journal which published the study. ‘Now we have a much better idea why this is the case – our brown fat stops working as we age. ‘Unfortunately, until a way to turn it back on is developed, we’ll have to be prepared to eat more salads and lean proteins, while logging more miles on the treadmill than our younger counterparts.’
In the latest study, the Japanese researchers also found a possible metabolic switch that could reactivate brown fat. This discovery could pave the way for the development of new treatments for obesity-related conditions such as diabetes, heart disease, high blood pressure and some cancers. People can avoid middle-aged spread by exercising regularly and by eating a low-fat, high-carbohydrate diet – but it is only effective if the carbohydrates that are consumed are from high-fibre, unprocessed sources
Researchers at the University of Shizuoka, in Japan, made the discoveries by studying two groups of mice. The first group had the platelet-activating factor receptors (PAFR) gene knocked out, making them become obese. The second group was normal. The researchers discovered that the PAFR-deficiency caused the brown fat to malfunction and this caused obesity as a result of reduced thermogenic activity. Many people worry about their middle-aged spread being unattractive, but it is also bad for health. Fat around the organs is linked to diabetes and heart disease while carrying a ‘pot belly’ increases the risk of heart problems.
Just three or four inches around the abdomen can be an external sign of a build-up of fat in the arteries.
It is thought that to maintain a steady weight, people over the age of 45 need to eat 200 fewer calories a day than those who are younger. There are various theories as to how best to avoid middle-aged spread. One study suggested a low-fat, high-carbohydrate diet could be the key to staying slim – but this diet is only effective if the carbohydrates consumed are from high-fibre, unprocessed foods.
Another expert, Marie Savard, says the best option is 30 to 45 minutes of moderate intensity exercise at least five days a week.