Many people regain weight after losing substantial weight, but the risk of developing various diseases and the risk of dying had not been quantified. A new study that has followed participants for 30 years after bariatric surgery investigated this.
Major and sustained weight loss after bariatric surgery is well known to reduce the risk of developing cardiovascular disease and diabetes and the risk of dying, but what happens when people regain weight?
A new study investigated this, and the results diverge: regaining some weight was associated with an increased risk of developing disease but not an increased risk of dying.
“Our results suggest that people who have lost substantial weight should be supported in avoiding regaining weight, which would increase their risk of developing disease. We need much more knowledge about how different weight change patterns affect people’s health in the long term,” explains a researcher behind the study, Kajsa Sjöholm, Institute of Medicine, Sahlgrenska Academy at the University of Gothenburg, Sweden.
The research has been published in Lancet Regional Health – Europe.
Followed participants for 30 years
The researchers aimed to learn more about how regaining weight following substantial weight loss affects people’s health.
They examined data from the Swedish Obese Subjects study on 1,346 people who have been monitored closely since they underwent bariatric surgery between 1987 and 2001.
Some participants did not regain weight after bariatric surgery, but others did, and the researchers thus investigated whether regaining weight affected long-term health over 30 years.
At the time of bariatric surgery, the participants were on average 48 years old and had an average body-mass index of 42.
The researchers compared participants who had regained more than 20% of the weight lost after one year in the four years after surgery with participants who had not regained weight or had regained less than 20% of the weight they had lost after one year.
In another analysis, the researchers compared those who had regained more than 30% of the weight originally lost with those who had not regained weight or had regained less than 30% of the weight originally lost.
The researchers investigated differences in mortality and the development of cardiovascular disease, microvascular disease and cancer.
“This is the first time anyone has investigated this in a large study over many years. The results bring us closer to determining whether regaining weight after achieving substantial weight loss is dangerous, which worries many patients and doctors,” says Kajsa Sjöholm.
Mortality risk not increased
After an average of 30 years of follow-up, regaining weight after substantial weight loss was associated with an increased risk of developing some diseases but not others and it did not affect mortality risk.
The participants who had regained more than 20% of the weight they had lost had an increased risk of developing microvascular disease, and their risk of developing cardiovascular disease was elevated but not statistically significant. However, there was no increased risk of developing cancer and no increased mortality risk.
Participants who had regained more than 30% of the weight lost had an increased risk of developing both cardiovascular disease and microvascular disease but not cancer and no increased mortality risk.
“The results are both positive and negative. Being able to tell people that on average, regaining a little weight does not increase their mortality risk is very good, but we should be aware of their increased risk of developing both cardiovascular disease and microvascular disease. Therefore, we cannot say that regaining weight is not dangerous following substantial weight loss,” notes Kajsa Sjöholm.
Much more knowledge required
According to Kajsa Sjöholm, the study improves understanding of how regaining weight again after substantial weight loss affects health. However, the results are only one piece of a large puzzle that researchers would like to learn more about.
The researchers would also like to know more about whether regaining weight after weight loss achieved with lifestyle changes versus medication affects the subsequent health risk.
“Unfortunately, conducting such studies poses significant challenges, since they require decades of follow-up to determine how weight loss or weight gain affects the risk of illness and dying,” says Kajsa Sjöholm.
And how do the extent of the weight loss and how rapidly is it achieved affect health?
“We can learn much from these types of data, and this can help us to advise people who want to lose substantial weight on how to achieve this in the healthiest way possible and the potential risks associated with regaining some weight later,” concludes Kajsa Sjöholm.
