"These findings highlight how difficult it is for people with obesity to achieve and maintain even small amounts of weight loss," says Dr. Fildes.
The likelihood of severely obese people reaching a normal weight was even more remote - with just 1 in 1,290 men and 1 in 677 women achieving this.
First author of the study, Dr. Alison Fildes, from the Division of Health and Social Care Research at King's College, says that "losing 5-10% of your body weight has been shown to have meaningful health benefits and is often recommended as a weight loss target. These findings highlight how difficult it is for people with obesity to achieve and maintain even small amounts of weight loss."
Adding that the main treatment options for obese patients are weight management programs, the findings of the study suggest "the current system is not working for the vast majority of obese patients."
In the study, the team used electronic health records covering the period 2004-12 to track the weight of 129,194 men and 149,788 women. Patients who received weight-loss surgery were excluded from the study.
The study found that the annual chance of obese people reducing their body weight by 5% was 1 in 12 for men and 1 in 10 for women. Of these participants who successfully lost 5% of their body weight, 53% regained it within 2 years and 78% regained it within 5 years.
Participants with a body mass index (BMI) of 30-35 had a 1 in 210 chance of reaching a normal body weight if they were male and a 1 in 124 chance of this if they were female. However, only 1 in 1,290 men and 1 in 477 women with a BMI of more than 40 were likely to reach a normal body weight.
More than a third of the participants were found to experience weight cycling - where their weight both increased and decreased.
Current treatments are failing obese patients
Dr. Fildes concludes that current obesity treatments fail to help obese patients achieve sustained weight loss:
"Once an adult becomes obese, it is very unlikely that they will return to a healthy body weight. New approaches are urgently needed to deal with this issue. Obesity treatments should focus on preventing overweight and obese patients gaining further weight, while also helping those that do lose weight to keep it off. More importantly, priority needs to be placed on preventing weight gain in the first place."
Senior author Prof. Martin Gulliford says that rather than focusing on ineffective strategies to cut calories and boost physical activity, the greatest opportunity "for stemming the current obesity epidemic is in wider-reaching public health policies to prevent obesity in the population."
Recently, Medical News Today looked at a study that identified a new genetic form of obesity and type 2 diabetes. This new form of obesity was discovered following the genome sequencing of an "extremely obese" young woman who also exhibited increased appetite, type 2 diabetes, learning difficulties and problems with her reproductive system.