UNEXPLAINED DISTURBANCE IN BODY-WEIGHT REGULATION - DIAGNOSTIC OUTCOME ASSESSED BY DOUBLY LABELED WATER ADD BODY-COMPOSITION ANALYSES IN OBESE PATIENTS REPORTING LOW-ENERGY INTAKES

Subjects Ten patients who had long-term disturbances in body weight re gulation, were referred over a 3-year period for obesity evaluation, a nd reported low energy intakes (<1,200 kcal/day) Objective To ascertai n whether these patients had a low energy expenditure and thus reduced energy requirement, and/or whether they were misreporting their energ y intake. Design Comparison of outcome measures in referred patients a nd in obese control patients who did not report low energy intakes and disturbances in body weight regulation. Main outcome measures Low ene rgy expenditure was evaluated with serum thyroid hormone levels, resti ng metabolic rate (RMR), thermic effect of food (TEF), and total energ y expenditure (TEE) by doubly labeled water technique. Misreporting of energy intake was evaluated by comparing patients' self-reported ener gy intake with energy intake estimated by doubly labeled water and bod y composition analyses over a 14-day period. Statistical analyses perf ormed Low energy expenditure was considered present in a patient if RM R or TEE was more than 15% below predicted values according to results horn the control group. Patient group TEF was compared with TEF resul ts observed in the control group. Results All patients had normal seru m thyroid hormone levels. Eight patients had RMR and TEE values within 15% of predicted values and were substantially underreporting their e nergy intake. One patient had low TEE (-19%) and a normal RMR, a findi ng that implies a low level of physical activity. This patient also un derreported energy intake as estimated by the doubly labeled mater tec hnique during the study (-38%). The 10th patient had a low RMR (-23.2% ) and TEE (-25.0%), the mechanism of which was uncertain. This patient 's reported food intake over the 14-day period was accurate but was le ss than her long-term intake over months or years as suggested by doub ly labeled water TEE estimates. The TEF response in patients was not s ignificantly different from that observed in the control group. Conclu sions Underreporting of energy intake from foods is a frequent finding in patients with disturbances in body weight regulation who are refer red for obesity evaluation. Severe underreporting may be detectable by means of screening measures available to most dietitians. Low energy expenditure, due either to physical inactivity or to metabolic factors , is also observed. Modern evaluation methods provide new insights int o patients with weight regulatory disturbances and at the same time st imulate important new research questions.