Weight loss becomes increasingly difficult with the onset of obesity due to alterations in the physiological systems that modify appetite and metabolism. Patients following lifestyle recommendations for weight loss may face challenges with adherence when patients lack information on their metabolic rate. The objective of this study was to assess the feasibility and acceptability of a handheld indirect calorimeter for measuring resting energy expenditure (REE) in a bariatric patient before and after surgery.


We present a 38 yo male with a BMI of 55.7 kg/m2 at entry to care. The participant elected for laparoscopic sleeve gastrectomy (LSG) following 6 months of insurance-mandated weight loss. During clinic visits, patient weight, BMI and estimated basal metabolic rate (BMR) by Tanita® scale system were obtained. Food and exercise logs were collected and pre- and post-operative nutrition recommendations, exercise advice, and encouragement for behavioral modifications were given. Beyond standard care, the patient received a portable metabolic tracker, BreezingTM, that used indirect calorimetry to measure REE and respiratory quotient (RQ, Energy Source). REE was measured weekly for 3 months pre-surgery and 2 months post-surgery.


At the initial clinic visit, the patient weighed 439.4 lbs. After 7 months of pre-operative weight loss (64 lbs) he began using BreezingTM. During the 5 months of BreezingTM use the patient obtained 19 REE measurements. Initial REE was 2130 kcal/day with a mean pre-operative value of 2575±219 kcal/d. At one month post-surgery REE decreased to 2090 kcal/day and then increased to 2700 kcal/d by the end of the second post-operative month at which time the patient weighed 363.4 (excess weight loss of 28%). RQ was representative of both carbohydrate and fat utilization at nearly all measurements. REE (BreezingTM) and BMR (Tanita®) measures were not correlated (r=0.105, p=0.895) with a mean difference between measures of 176±279 kcal/d (range: -33 to 577 kcal/d).


Differences between REE and BMR values were highly variable. Hydration status, recent physical activity and dietary behaviors may have contributed to fluctuations in Tanita® values. These preliminary data indicate that the BreezingTM shows promise as a valid tool in the assessment of REE in bariatric patients before and after surgery, which may prove useful for maximizing the effect of weight loss programs.