BETHESDA, Md., Aug. 6 -- In the largest study of its kind, a majority of formerly obese men and women, who had been highly successful at significant long-term weight loss, reported that a trigger event or incident prompted them to lose and maintain weight, according to research published in the August American Journal of Clinical Nutrition.
Nearly 77 percent of the 629 women and 155 men recruited for the National Weight Control Registry study reported that a trigger event preceded their successful loss of large amounts of weight. About 32 percent of the participants described either a medical trigger (sleep apnea, low back pain, constant fatigue, aching legs or varicose veins), or an emotional trigger ("husband left me and my lawyer told me it was because I was too fat"). Women were more likely than men to report an emotional trigger. For over 11 percent of the subjects, the trigger event was seeing themselves in a mirror or a photograph. Slightly over 35 percent of the men said they "just decided to do it."
Compared to previous weight loss attempts, 82 percent of the participants felt they were more committed to making behavioral changes, and 72 percent were more interested in losing weight. Over 81 percent exercised more and 63 percent used a stricter dietary approach than employed previously.
Lead author Mary L. Klem, Ph.D., senior research fellow, department of psychiatry, University of Pittsburgh School of Medicine, along with four associates, including several from the University of Colorado Health Sciences Center, conducted the study. The researchers reported that the overweight persons in the registry lost an average of 66 pounds, and maintained at least a minimum of a 30-pound weight loss over 5.5 years. Almost 14 percent lost about 100 pounds of weight.
"Unfortunately, long-term follow-up of many behavioral weight loss programs, which are initially successful, indicates that most patients return to their baseline weights within three to five years after the end of treatment," said Dr. Klem. "All persons in this study were successful at losing weight and keeping it off. Surprisingly little is known about successful weight maintainers because of their rarity in university-based studies."
The article providing background on the successful weight loss maintainers appeared in the monthly peer-reviewed journal of the American Society for Clinical Nutrition. Approximately 55 percent of the participants used either a formal weight loss program or professional assistance to lose weight; 45 percent lost it on their own.
About 90 percent of the sample (566 women and 139 men) made significant changes both in their dietary intake and physical activity levels to achieve serious weight loss. Among those who modified their diets, approximately 88 percent to 92 percent limited intake of certain types of food; about 45 percent limited quantities of food eaten; and 44 percent counted calories. About 20 percent used liquid formula in their weight loss program.
"To maintain their new weight, both men and women say their fat intake was at or below the recommended limit of 30 percent of their diet," said Dr. Klem. "In fact, 33 percent of the sample reported consuming less than 20 percent of daily energy in the form of fat."
Participants ate regular meals, including occasional meals at restaurants. On average, they reported eating five times a day, with the majority of meals either being prepared at or eaten at home.
In addition to dietary changes needed to maintain lower weight, both male and female successful dieters regularly were involved in moderate to high intensity exercise. On average, they expended calories equivalent to walking 28 miles per week.
Among the 282 individuals who engaged in moderate intensity exercise, 48 percent performed stationary or road cycling, 25 percent aerobics, and 11 percent walked or ran on a treadmill.
Men participants were more likely than women to be involved in high intensity activities such as competitive sports and weight lifting.
To reduce weight, the American College of Sports Medicine (ACSM) recommends expending, during a weekly exercise program, a minimum of 1,000 kilocalories. (In medicine and dietetics, the energy content of food is measured in kilocalories, which are often referred to as calories). Seventy-one percent of the women and 79 percent of the men met or exceeded more than 1,000 kilocalories per week, while 50 percent of the women and 62 percent of the men exceeded 2,000 kilocalories per week, listed by ACSM as an optimal physical conditioning level. For a 132-pound person, one hour of jogging burns up 540 kilocalories.
Most of the participants involved in the study reported onset of obesity in childhood. About 46 percent of the sample noted that they first became overweight at less than 11 years of age; over 25 percent became obese between the ages of 12 and 18.
A large proportion of the registry also reported a family history of obesity, with 46 percent having one overweight biologic parent, and almost 27 percent two overweight biologic parents.
To enter the study, 35 percent of the group (274 individuals) provided "before" and "after" weight loss photos and 42 percent (352) offered the names of doctors, weight loss counselors, and other individuals to verify their weight loss.
The researchers plan to follow their weight loss registry members to determine the variables that either predict continued weight maintenance, or influence the regaining of weight.
The National Weight Control Registry was developed in 1993 by Dr. James Hill at the University of Colorado and Dr. Rena Wing at the University of Pittsburgh School of Medicine.
For additional information about the University of Pittsburgh Medical
Center, please access http://www.