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Size of adipose cells may indicate future weight gain

Researchers from Karolinska University Hospital Huddinge, Stockholm, Sweden, have suggested that it is possible to predict if someone is going to gain weight based on the size of their adipose cells after discovering that individuals with large adipose cells tend to lose weight over time, while those with small adipose cells gain weight. The findings were presented at the European Congress on Obesity (ECO 2024) in Venice, Italy.

The size and number of adipose cells are known to determine adipose mass, but their impact on long-term changes in body weight are unknown. To explore this further, Professor Peter Arner, of the Department of Medicine, Karolinska Institutet, Stockholm, Sweden, Dr Daniel P Andersson, Department of Endocrinology, from Karolinska University, and colleagues, measured cell volume (FCV, the size of the adipose cells) and adipose cell number (FCN) in abdominal adipose of 260 subjects (30% men) with an average age of 44 years and an average BMI32kg/m².


An average of 15 years (range 5–28 years) later, the participants were seen again and body weight (BW), BMI and total body adipose (BF) measured. Individuals undergoing bariatric surgery or receiving anti-obesity drugs (n=69) were excluded from the analysis.


They found that initial adipose cell volume and adipose cell number were significantly related to changes in all three measures (BW, BMI and BF) over time. Having a high number of adipose cells that were large was associated with decreases in the three measures, while having few, but small, adipose cells correlated with increases in weight, BMI and body adipose. This was the case whether or not individuals were living with obesity. The effects of FCV and FCN were additive and together explained 32%–35% of the variations in changes over time in BW/BMI/BF.


The associations between FCV and changes in BW, BMI and BF was still significant when initial age, physical activity, length of follow-up and sex were taken into account. Therefore, large cells were linked to future weight loss and small cells to future weight gain.


"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,” explained Arner. "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. 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 researchers concluded that FCV has a strong influence on long-term changes in body weight. Thus, measuring FCV early in life could be important for weight management later in life.

"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."


There are advantages, however, to having small adipose cells as people with small adipose cells have a better metabolic profile than people who are the same weight but have large adipose 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 adipose cells,” he added.

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