The prevalence of overweight and obesity is high and increasing. This also applies to older subjects. Beside this, there is a high prevalence of malnutrition in older subjects including people with overweight and obesity. The basis of nutritional therapy and thus an adequate nutrient intake is the assessment of energy need. On the other end, the assessment of individual energy requirements based on the gold standard, indirect calorimetry, is associated with feasibility difficulties in geriatric settings. To identify the most accurate predictive equations to determine resting energy expenditure (REE) in older subjects with overweight, 17 predictive equations were compared to indirect calorimetry measurement in a study population of 20 obese older subjects (mean BMI 33.7±4.5kg/m(2), min 29.1, max 43.7; mean age 79.8±8.1years, min 65, max 92; gender 5 males and 15 females) and 20 age-matched controls with a normal body weight (mean BMI 24.9±2.5kg/m(2), min 21.0, max 28.7; mean age 82.1±6.6years, min 71, max 91; gender 9 males and 11 females). The comparison of predictive equations estimating REE on the basis of regression analysis of body weight, height, sex, and age as independent variables and of indirect calorimetry as a dependent variable led to two significant observations: the predictive equations used led to a much better estimation of the REE in the control group than in the obese older subjects. In addition, the most accurate equation for estimating the REE in the obese older subjects has been shown to be that by Lührmann et al. Further studies are needed to assess the feasibility of using this equation in a routine geriatric setting.