Obesity

Probability of an Obese Person Attaining Normal Body Weight: Cohort Study Using Electronic Health Records

 * http://ajph.aphapublications.org/doi/pdf/10.2105/AJPH.2015.302773

Objectives. We examined the probability of an obese person attaining normal body weight.

Methods
We drew a sample of individuals aged 20 years and older from the United Kingdom’s Clinical Practice Research Datalink from 2004 to 2014. We analyzed data for 76,704 obese men and 99,791 obese women. We excluded participants who received bariatric surgery. We estimated the probability of attaining normal weight or 5% reduction in body weight.

Results
During a maximum of 9 years’ follow-up, 1283 men and 2245 women attained normal body weight. In simple obesity (body mass index = 30.0–34.9 kg/m2), the annual probability of attaining normal weight was 1 in 210 for men and 1 in 124 for women, increasing to 1 in 1290 for men and 1 in 677 for women with morbid obesity (body mass index = 40.0–44.9 kg/m2). The annual probability of achieving a 5% weight reduction was 1 in 8 for men and 1 in 7 for women with morbid obesity.

Conclusions
The probability of attaining normal weight or maintaining weight loss is low. Obesity treatment frameworks grounded in community-based weight management programs may be ineffective. (Am J Public Health. 2015;105: e54–e59. doi:10.2105/AJPH.2015.302773)

Obesity rate over time
Approximately 10 percent of U.S. adults were classified as obese during the 1950s. In 2011 to 2012, however, the CDC reported approximately 35 percent of U.S. adults were obese; the prevalence of obesity among American adults has more than tripled within the last six decades.Feb 1, 2016
 * https://www.google.com/search?q=obesity+rate+in+1960 (Featured snippets in search)

The key question is what is different from the 1950s. Some combination of those differences is what has changed the obesity rate.

Note that the 10% rate in the 1950s was not 0%. Some obesity is a normal state of population.