Losing weight can "reboot" fat tissue and return it to a healthier state
Losing weight can not only reduce the risks of diabetes and cardiovascular disease, but also markedly "heal" the adipose tissue itself - to a state close to that of non-obese people.
This is the conclusion reached by researchers at the University of Southern Denmark, who tracked how subcutaneous fat cells change at different stages of weight loss. The work was published in Nature Metabolism.
The team analysed subcutaneous adipose tissue samples from severely obese people at three points: before planned gastric bypass, after moderate weight loss of 5-10% (due to diet) and two years after surgery, when the participants had lost about 20-45% of their weight.
It was at the "far" point - two years after surgery - that the scientists saw the most pronounced changes.
The number of immune cells, which support chronic inflammation and worsen insulin sensitivity, decreased sharply in the adipose tissue. In parallel, the proportion of cells associated with blood vessels increased - which may mean that the tissue is better supplied with oxygen and nutrients. In addition, the activity of genes in different cell types generally "normalised" and became closer to the profile characteristic of people with a slim build.
At the same time, at the stage of moderate weight loss (5-10%), the researchers did not record a clear drop in inflammation in adipose tissue - although in clinical practice, even such a "minus" often already improves the overall sensitivity to insulin.
A possible explanation offered by the authors is that the early metabolic improvements may be due not to a reduction in inflammation, but to adipose tissue remodelling - for example, the growth of certain fat cell precursors and the strengthening of programmes that help to form new, healthier adipocytes.
The main finding of the work is that after significant weight loss, adipose tissue is able to recover substantially and that the "memory" of obesity, at least in a number of cellular and genetic traits, may be less persistent than previously thought.
The researchers emphasise that this helps to better understand why weight loss confers long-term metabolic benefits - and where exactly in the tissues these benefits are 'locked in'.