An obese man has a one in 210 chance of achieving a normal body weight, and a woman a one in 124 chance, according to a large population-based cohort study of obese adults in the United Kingdom.
The study, published online July 16 in the American Journal of Public Health, is one of the first to quantify the chance of an obese person attaining a normal body weight or even a 5% reduction in body weight.
“The findings show just how difficult it is for people with obesity to lose weight and keep it off,” first author Alison Fildes, PhD, from University College London, United Kingdom, told Medscape Medical News. (Dr Fildes conducted the research while at King’s College London, United Kingdom.)
The study findings make clear that current strategies to tackle obesity are not effective and do not help the majority of obese patients lose weight and maintain that weight loss. “Most important, there is a need for effective public-health policies aimed at obesity prevention,” Dr Fildes added.
Obesity is a growing global health concern and, in the United Kingdom, if not elsewhere, the main treatment option available for obese patients is to follow a weight-management program accessed through primary care. Against this background, Dr Fildes explained their motivation for the study: “This framework envisages that patients may transition from obesity to a healthier body weight. We therefore saw a need to understand and quantify the frequency with which weight loss and weight-loss maintenance occurs in a large population.”
Large, Population-Based Study
Dr Fildes and colleagues calculated the probability of an obese individual attaining a normal or 5% reduction in body weight using data from the UK Clinical Practice Research Datalink, which includes information from electronic primary-care health records. The authors tracked the weight of 278,982 participants aged 20 years or older from 2004 to 2014. Weight changes were estimated using a minimum of three records of body mass index (BMI) per patient. Patients who had received bariatric surgery were excluded.
Over 9 years of follow-up data, the annual probability of obese patients achieving 5% weight loss was one in 12 for men and one in 10 for women with simple obesity (BMI 30–35 kg/m2), but the probability increased for people in higher categories of obesity. In patients with morbid obesity (BMI 40.0–44.9 kg/m2), the probability was one in 8 for men and one in 7 for women.
However, many fewer individuals were able to achieve a normal body weight. Overall, only 1283 of 27,966 men and 2245 of 27,251 women with a BMI of 30 to 35 kg/m2 reached their normal body weight, equating to an annual probability of attaining normal weight of one in 210 for men and one in 124 for women. Among those with morbid obesity at baseline, the frequency increased to one in 1290 for men and one in 677 for women.
In addition, maintaining weight loss also proved difficult for these patients. “For those who achieved 5% weight loss, 53% regained at least some of this weight within 2 years, and 78% had regained weight within 5 years,” Dr Fildes remarked.
“For people with a BMI above 35 kg/m2, the probability of achieving a normal BMI was even lower,” reported Dr Fildes. “Weight cycling, with both increases and decreases in body weight, was also observed in more than a third of patients.”
Reflecting on the results, she added that although previous research indicated the difficulty of achieving and maintaining weight loss for people with obesity, “I was still surprised by how low the numbers actually were.”
Effectiveness of Weight-Management Programs
The authors write that, “These findings raise questions concerning whether current obesity treatment frameworks, grounded in weight-management programs accessed through primary care, may be expected to achieve clinically relevant and sustained reductions in BMI for the vast majority of obese patients and whether they could be expected to do so in the future.”
A target of 5% to 10% body weight loss is often recommended for obese patients receiving weight-management interventions. “It may be unrealistic to expect people with severe obesity to achieve a normal BMI,” Dr Fildes pointed out, “but as our findings suggest, a target of 5% weight loss is more achievable, and even this small reduction in weight has been shown to have important benefits for health.”
The research did not explore the efficacy of current weight-management programs or measure how many participants were pursuing weight-management interventions. However, previous work has found that weight-management interventions may be difficult to access with small and poorly maintained effects on body weight, acknowledged Dr Fildes. “When people lose weight, they often regain this weight quite quickly, and this study highlights how difficult it is for people to maintain even small amounts of weight loss.”
She noted that obesity treatment programs should prioritize preventing further weight gain and support maintenance of weight loss.
“It is also important to remember that there are small and achievable lifestyle changes, in terms of increasing physical activity, reducing sedentary behavior, and making adjustments to diet, which can have a beneficial impact on health regardless of weight.”