Some people find it harder to lose weight than others, but why is this? A new study has identified a molecule in fat cells that could be to blame.

Researchers found that the fat cells of people who are obese show higher expression of a molecule called lysyl oxidase (LOX).

LOX is associated with fibrosis, or "scarring," of fat tissue, which, as previous research has shown, can hamper weight loss efforts.

Study co-author Dr. Katarina Kos, who works in the Diabetes and Obesity Research Group at the University of Exeter Medical School in the United Kingdom, and colleagues recently reported their findings in the journal Metabolism.

It is thought that around 1 in 3 adults in the United States are obese, which puts them at increased risk of type 2 diabetes, stroke, heart disease, and some forms of cancer.

A lack of exercise and a poor diet are the primary causes of obesity, so it's no surprise that eating a healthful diet and increasing physical activity are the first strategies we try in an attempt to shed the pounds.

But these interventions can produce mixed results: some individuals see the pounds fall off, while others find it much more challenging. The new study may have uncovered one explanation for the latter.

Higher LOX levels in people who are obese

For their study, Dr. Kos and colleagues analyzed samples of abdominal fat tissue that had been taken from obese individuals before they underwent weight loss surgery.

Compared with abdominal fat tissue samples of leaner subjects, the analysis revealed that the fat tissue of obese people had greater expression of the LOX molecule, which is a cause of fat tissue fibrosis.

On further investigation, the researchers found that the increase in LOX expression was driven by an increase in oxygen deprivation and inflammation in fat cells, which occurs when fat cells become larger.

The scientists explain that when fat cells undergo this type of stress, they lose their ability to store excess calories. As a result, these calories become stored as fat around important organs, such as the liver and heart, and this is associated with numerous health problems, including heart disease and type 2 diabetes.

Unfortunately, studies have shown that fat tissue fibrosis can make it harder for individuals to lose weight. "But, this does not mean that scarring makes weight loss impossible," Dr. Kos emphasizes.

"Adding some regular activity to a somewhat reduced energy intake for a longer period makes weight loss possible and helps the fat tissue not to become further overworked," she continues. "We know that doing this improves our blood sugar and is key in the management of diabetes."

'We need to look after our fat'

What's more, the team's findings indicate that targeting the LOX molecule could be one way to prevent fat cell fibrosis and possibly make weight loss easier, but more studies are needed to confirm this theory.

Dr. Kos notes that further research is also needed in order to identify other ways to prevent fat tissue fibrosis. In the meantime, she says that increasing our physical activity could help.

"There is evidence that once fat tissue becomes scarred, despite weight loss, it may not recover fully," she says. "We need to look after our fat tissue, which can cease to cope if it is overworked when being forced to absorb more and more calories."

"As a clinician," Dr. Kos concludes, "I would advise exercise or at least a 'walk' after a meal which can make a great difference to our metabolic health."