Public Release: 

Study finds lifestyle modification and weight loss medication superior to either approach used alone

Combination of both approaches increases weight loss two-fold

University of Pennsylvania School of Medicine

According to a study that appears in the November 17 issue of The New England Journal of Medicine, researchers at the University of Pennsylvania School of Medicine found that weight loss medications work best when combined with dieters' own efforts to modify their eating and exercise habits. Study participants who received combined therapy lost significantly more weight than all other groups.

"Weight loss medications helped people lose weight, as did a program of lifestyle modification designed to improve eating and exercise habits. However, we found that a combination of the two approaches produced approximately twice the weight loss of either intervention used alone," reported Thomas A. Wadden, Ph.D., lead author of the paper and director of the Weight and Eating Disorders Program at Penn. The research was supported by the National Institute of Diabetes and Digestive and Kidney Disease, one of the National Institutes of Health.

Study Protocol

The one-year study examined 180 women and 44 men with an average age of 44 years, weight of 235 lb., and body mass index of 37.7 kg/m2. Participants were randomly assigned to one of four treatment groups, all of which were instructed to consume 1200-1500 calories a day and to exercise 30 minutes a day, most days of the week.

Participants in the first group were prescribed 10-15 mg/d of the weight loss medication sibutramine (MERIDIATM, Abbott Laboratories) and had 8 brief (10-15 min) visits during the year with a primary care practitioner. These individuals received minimal instruction in lifestyle modification, consistent with the manner in which most physicians prescribe weight loss medications.

Individuals in the second group received group lifestyle modification alone, which is recommended as the first step of treatment for all overweight and obese individuals. They attended a total of 30 group sessions (90 minutes each) over the year and were instructed to keep daily records of their food intake and physical activity which were reviewed during the sessions.

Participants in the third group received a combination of the first two approaches (i.e., sibutramine plus group lifestyle modification) to determine whether the combined therapy would be superior to either approach used alone.

Individuals in the fourth group received sibutramine and met with a primary care practitioner 8 times during the year, and were also encouraged to keep daily food and activity records. This group was included to see if practitioners could provide effective lifestyle modification counseling during brief visits.

At the end of 1 year, participants in the four groups lost 11.0 lb (sibutramine alone), 14.7 lb (group lifestyle modification alone), 26.6 lb (combined therapy), and 16.5 lb (sibutramine plus brief lifestyle counseling), respectively. Participants who received combined therapy lost significantly more weight than those in the three other groups.


"These findings clearly indicate that weight loss medications are most effective when combined with a comprehensive program of lifestyle modification," said Robert Berkowitz, M.D., a co-author of the study and Associate Professor of Psychiatry at Penn. "Sibutramine appears to modify internal signals that control hunger and fullness, while lifestyle modification teaches individuals to control the external food environment - for example, by keeping food records or shopping for groceries from a list," added Berkowitz, who is also Chair of Psychiatry, The Children's Hospital of Philadelphia. Participants who received sibutramine plus brief lifestyle counseling lost significantly more weight than those treated by sibutramine alone during the first 18 weeks (18.7 vs 13.6 lb, respectively), suggesting that primary care providers can provide effective lifestyle counseling during routine office visits.

Examining all 224 participants, weight loss at the end of the year was associated with a 14.7% reduction in triglyceride levels and an 18.9% decrease in insulin resistance, a condition that usually precedes the development of type 2 diabetes. Larger weight losses were associated with greater improvements in these measures, as well as with greater improvements in high-density-lipoprotein cholesterol (i.e., the "good" cholesterol).

"Our findings indicate that weight loss medications should be used only as an adjunct to a program of lifestyle modification, as recommended by both the National Institutes of Health and the Food and Drug Administration," said Wadden. "Lifestyle modification can begin with efforts to reduce portion sizes, keep a daily food log, and increase daily walking. The more approaches you combine, the less you'll weigh," he added.


PENN Medicine is a $2.7 billion enterprise dedicated to the related missions of medical education, biomedical research, and high-quality patient care. PENN Medicine consists of the University of Pennsylvania School of Medicine (founded in 1765 as the nation's first medical school) and the University of Pennsylvania Health System.

Penn's School of Medicine is ranked #2 in the nation for receipt of NIH research funds; and ranked #4 in the nation in U.S. News & World Report's most recent ranking of top research-oriented medical schools. Supporting 1,400 fulltime faculty and 700 students, the School of Medicine is recognized worldwide for its superior education and training of the next generation of physician-scientists and leaders of academic medicine.

Penn Health System comprises: its flagship hospital, the Hospital of the University of Pennsylvania, consistently rated one of the nation's "Honor Roll" hospitals by U.S. News & World Report; Pennsylvania Hospital, the nation's first hospital; Penn Presbyterian Medical Center; a faculty practice plan; a primary-care provider network; two multispecialty satellite facilities; and home health care and hospice.

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