We determined the total energy expenditure (TEE) of healthy overweight or obese people, and those with impaired glucose tolerance and/or impaired fasting glycemia (IGT/IFG), or type 2 diabetes (T2DM) using the doubly-labeled water method. As a second purpose, we compared the measured TEE with the target energy intake recommended in the treatment guidelines for diabetes. The participants were normal glucose tolerance (NGT), and IGT/IFG ( n =11) and T2DM ( n =9) patients, who were 50-59 y and had a body mass index >25 kg/m². The median TEE/body mass (BM) values were 32.6, 33.3, and 34.4 kcal/kg BM and the TEE/target BM values (target BM: BM at a BMI of 22 kg/m²) were 43.7, 50.2, and 46.5 kcal/kg target BM for each group, respectively, and did not differ significantly among them. Obese Japanese participants with T2DM in this study had lower TEE/BM than previously studied in non-obese participants with T2DM. In IGT/IFG or T2DM patients, if 30 kcal/kg target BM was used as the energy coefficient, on the basis of the treatment guidelines, the difference between TEE and the target energy intake would be −1,174±552 kcal (−38±11%). When 35 kcal/kg target BM was used as the energy coefficient, the difference between TEE and the target energy intake would be −877±542 kcal (−27±13%). Thus, the energy coefficients used to estimate target energy intake during lifestyle modification in obese/overweight patients with T2DM are considered to be quite low during the first step of diet therapy.