Discussion.—The patterns revealed suggest thatchanges to incentive structures have substantially altereddentists’ behavior relative to the treatments prescribedfor patients. Significant numbers of dentists appear to be fo-cused on hitting their UDA contract targets in the way that ismost efficient for them. This involves a shift toward treat-ments where the rewards are high relative to costs ratherthan selecting treatments based on clinical factors alone.Also, changes in co-payment fees were introduced in 2006and may have influenced patient choices, which couldhave altered treatment selections.

Clinical Significance.—Professional behav-iors are influenced by the incentive structuresthat they face. The desire to maintain or in-crease income is strong and may overpower or

undermine ethical motivations. Dentists maynot see these changes in behavior as antitheticalto professional norms. Policy makers mustclearly understand what they expect the pro-gram to achieve and design an incentivestructure that will not promote unintendedconsequences.

Tickle M, McDonald R, Franklin J, et al: Paying for the wrong kind ofperformance? Financial incentives and behavior changes inNational Health Service dentistry 1992-2009. Community DentOral Epidemiol 39:465-473, 2011

Reprints available from M Tickle, School of Dentistry, The Univ ofManchester, Higher Cambridge St, Manchester M15 6FH, UK; fax:þ44 161 275 6299; e-mail: martin.tickle@manchester.ac.uk

EXTRACTS

REBOUND BY HORMONES

Up to 80% of overweight people who slim down appreciably through dieting gain some or all of the lost weightback within a year. The reason for this rebound weight gain may go beyond willpower to the effects of hunger-related hormones that were disrupted by dieting and weight loss. Altered hormone levels can remain for a year ormore, causing the individual to have increased appetite and undermining the dieter’s best efforts.

Hormones found in the gut, pancreas, and fatty tissue strongly influence body weight and processes such as hungerand burning calories. A drop in the percentage of body fat causes a decline in the levels of some hormones such asleptin, which signals satiety, and an increase in others such as ghrelin, which stimulates hunger. New research hasshown that altered hormone levels remain after weight loss. Fifty overweight or obese men and women followeda very low-calorie diet for 10 weeks, then their hormone levels were tracked for 1 year by researchers at the Universityof Melbourne’s Heidelberg Repatriation Hospital in Victoria, Australia. Subjects lost an average of 30 pounds, orapproximately 10% of their starting weight. Blood tests revealed the average levels of several hormones (includingleptin, ghrelin, and insulin) were altered by the weight loss. Subjects also reported being hungrier before and afterbreakfast than before dieting. They resumed a normal diet after the 10 weeks. After 1 year, subjects gained an averageof 12 pounds and their hormone levels were only partially stabilized. Hunger levels remained elevated.

Dr Charles Burant of the University of Michigan Nutrition Obesity Research Center recognized these hormonechanges as a well-known evolutionary survival tactic. He said, ‘‘Multiple mechanisms have been developed, overeons of evolution, to get you to regain weight once you lose it . . . to tell your brain you’re hungry and to ensurethat you don’t stop eating. If you don’t have those drives, you wouldn’t be alive.’’ Today calories are readily availableand physical exercise is largely not needed for day-to-day survival. As a result, these biologic drives contribute toobesity. However, Dr Joseph Proietto, lead researcher of the Australian study, feels personality and psychologicalfactors may influence a person’s ability to manage chronic hunger and overcome these drives.

Research is being conducted seeking how to restore hormone levels in people who lose weight. Dieters injectedwith replacement leptin hormones, for example, are better at maintaining or continuing their weight loss. Researchersshould be looking for ways to support people who lose weight that are similar to those offered to diabetic patients whodonot have enough insulin in their bodies. Appetite suppressantsmay also offer hope inhormone andobesity research.Until then, weight-loss surgery is an option for severely obese people who cannot otherwise maintain weight loss.

[A MacMillan, Health.com: After Dieting, Hormone Changes May Fuel Weight Regain. Health Magazine, October26, 2011]

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