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Obesity is a Risk – Even for People with Healthy Habits

A healthier lifestyle mitigates but does not obliterate various comorbidity risks associated with obesity, according to a new study of nearly half a million UK Biobank participants.

Researchers said that it had been uncertain whether a healthy lifestyle could offset the risk of obesity. Particularly, it remained unclear to what extent specific combinations of healthy lifestyle factors were associated with a reduced risk of obesity-related diseases other than cardiovascular disease. 

For the study, published in JAMA Network Open, they set out to estimate the association between four lifestyle factors: smoking, alcohol consumption, physical activity, and diet, with the incidence of major obesity-related diseases in adults with obesity compared with those who had a healthy weight.

They obtained data on 438,583 UK Biobank participants with a mean age of 56.5 years (range 40-73), 55.1% female, and free of major obesity-attributable diseases at baseline on enrolment from 2006 to 2010. Participants were given a binary score for each of the four lifestyle factors, either 1 if they met the criterion for a healthy lifestyle or 0 if they did not.

They were then followed prospectively for disease diagnoses for a mean of 12.8 years, with data analysis between 1 December 2021 and 31 October 2022.

At baseline 107,041 of the cohort (24.4%) were obese. During follow up, 150,454 participants (34.3%) developed at least one of the studied diseases. 

'Modest' Risk Reductions for Obesity-related Diseases

Analysis showed that adherence to a healthy lifestyle was associated with a reduced risk of a wide range of obesity-related diseases, the researchers reported, although the association was "modest".

Compared with adults of healthy weight, those with obesity and all four healthy lifestyle factors remained at higher risk of several outcomes irrespective of the lifestyle score, with adjusted hazard ratios ranging from 1.41 for arrhythmias to 7.16 for diabetes.

Compared with obese adults who had zero healthy lifestyle factors, individuals with obesity who met all four healthy lifestyle factors were at lower risk of:

  • Hypertension (HR, 0.84; 95% CI 0.78 to 0.90)
  • Ischemic heart disease (HR, 0.72; 95% CI 0.65 to 0.80)
  • Arrhythmias (HR, 0.71; 95% CI 0.61 to 0.81)
  • Heart failure (HR, 0.65; 95% CI 0.53 to 0.80)
  • Arteriosclerosis (HR, 0.19; 95% CI 0.07 to 0.56)
  • Kidney failure (HR, 0.73; 95% CI 0.63 to 0.85)
  • Gout (HR, 0.51; 95% CI 0.38 to 0.69)
  • Sleep disorders (HR, 0.68; 95% CI 0.56 to 0.83)
  • Mood disorders (HR, 0.66; 95% CI 0.56 to 0.78)

The results confirmed the lower risk of mortality and cardiovascular disease in adults with obesity meeting the four healthy lifestyle factors, and extended the findings to kidney failure, gout, sleep disorders, and mood disorders, the authors said. The association between a healthy lifestyle and diseases was independent of other potential confounders, such as age, sex, and socioeconomic status.

The researchers concluded: "The findings suggest that although a healthy lifestyle seems to be beneficial, it does not entirely offset the health risks associated with obesity."

Obesity Co-morbidities 'Staggering'

According to the Royal Society for Public Health, obesity costs the NHS £4.2 billion a year. The Society said that without urgent and radical action, costs would rise to £10 billion a year by 2050. 

"Obesity is the most prevalent chronic disease worldwide," said the study authors, who described the higher rates of obesity-associated mortality and comorbidities, such as diabetes, cardiovascular disease, chronic kidney disease, and several types of cancer, as "staggering".

"A suboptimal lifestyle is a major preventable cause of obesity and its associated comorbidities," they stressed. "As such, interventions to improve lifestyle are an opportunity to optimise the management of obesity."

Nonetheless, although "obesity is a strong risk factor for comorbidities", a healthy lifestyle "may not be sufficient to attenuate the risk". In contrast, studies have shown the potential benefits of weight loss in preventing comorbidities among adults with obesity.

"Thus, supporting people to reduce their body weight in addition to promoting healthy behaviours may bring additional benefits to reduce the risk of developing comorbid diseases and extend disease-free life expectancy in obesity," they said.

Lifestyle Changes 'Not Enough'

Asked to comment by Medscape News UK, Katharine Jenner, director of the Obesity Health Alliance, said: "This study suggests that lifestyle changes alone – even if they are effective – will not be enough to prevent the multiple types of harm associated with excess weight.  

"Obesity is a chronic, relapsing condition with many causes. It is essential that we tackle the root causes, such as the flood of unhealthy food and drink that is constantly marketed and promoted to us.

"This Government can turn the tide on obesity, but they cannot rely on people changing their lifestyle as a solution. They must make it easier, cheaper, and more appealing to buy healthier food and drinks, and to prevent people from gaining excess weight throughout the life-course."

The study was funded by the British Heart foundation, Alzheimer's Society, UK Dementia Institute, Foundation LeDucq, NHS Research Scotland, Stroke Association and Garfield-Weston Foundation, and the NIHR.