Study suggests fat cell size could predict weight changes over time

By Stephen Beech via SWNS

The size of a person’s fat cells may be key to whether they pile on the pounds, according to a new study.

Researchers found people with large fat cells tend to lose weight over time, while those with small fat cells gain weight.

The Swedish study suggests that it is possible to predict if someone is going to gain weight based on the size of their fat cells.

Previous research has shown that the size and number of fat cells determine how much body fat someone has, known as "fat mass".

But the cells' impact on long-term changes in body weight had been unclear.

The Swedish team measured cell volume and fat cell number (FCN) in abdominal fat of 260 people with an average age of 44 and an average body mass index (BMI) of 32. Anyone with a BMI over 30 is considered clinically obese.

An average of 15 years later, the participants were seen again and their body weight, BMI and total body fat measured. Any undergoing bariatric surgery or receiving anti-obesity drugs were excluded from the analysis.

Initial fat cell volume and fat cell number were "significantly" related to changes in all three measures, according to the findings.

Having a high number of fat cells that were large was associated with decreases in the three measures, while having few, but small, fat cells correlated with increases in weight, BMI and body fat.

That was the case whether or not the person was obese, according to the researchers.

The effects of fat cell volume and FCN were additive and together explained 32 per cent to 35 percent of the variations in changes over time in weight, BMI and total body fat.

The team found that associations between fat cell volume and changes in weight, BMI and total body fat was still "significant" when initial age, physical activity, and sex were taken into account.

They said that, in other words, large cells were linked to future weight loss and small cells to future weight gain.

Study co-author Professor Peter Arner, of the Karolinska Institute, said: “We can only speculate as to why the size of a person’s fat cells seems to predict their future weight.

"Body weight decreases when energy expenditure exceeds intake and the body burns off fat to compensate.

"Our results suggest that the loss of large fat cells makes more of an impact on weight than the loss of small ones.

“It is a bit like having a room filled to the top by few large balloons or many small ones. It is easier to make empty space in the room by letting out air from the big rather than the small balloons.”

As to why having small cells might make it easier to gain weight, he said: “Conversely it is easier to fill up the room if many small balloons increase their volume a bit, as compared with having few large balloons and filling them up just a bit.”

The research team concluded that fat cell volume (FCV) has a "strong influence" on long-term changes in body weight.

They say that measuring FCV early in life could be important for weight management later in life.

Prof Arner said: “It could be of great clinical value to have information about fat cell size before starting a weight management program.

"If it is the case that those with large fat cells find it easier to lose weight, those with smaller cells could be given extra support.

“Unfortunately, there isn’t an easy way of measuring fat cell size at present – but it is something we are working on and we’re close to coming up with a solution.”

But he says there are advantages to having small fat cells.

Prof Arner added: “It is well known that people with small fat cells have a better metabolic profile than people who are the same weight but have large fat cells.

“This means that if someone with small fat cells does gain weight, it may not raise their risk of conditions such as type 2 diabetes and high blood pressure as much as if they had large fat cells.”

The findings are due to be presented at the European Congress on Obesity (ECO) in Venice, Italy.