Dehydration, assessed by urine and blood evaluation, is a risk factor for chronic kidney disease (CKD). The association between water deficit, as determined by a dietary assessment, and CKD prevalence is unclear. Therefore, this study aimed to clarify this association among adults in the USA. This cross-sectional study included the data of 9332 participants aged 18 years or older from the 2009–2012 National Health and Nutrition Examination Survey. Water turnover was calculated using an equation developed by the International Doubly Labelled Water Database Group. Total water intake was assessed by 24-h dietary recall on ≥ 1 d. Water deficit was defined as the ratio of water intake to water turnover. CKD was defined as an estimated glomerular filtration rate < 60 ml/min/1·73 m2, calculated by the 2021 CKD Epidemiology formula. OR for CKD prevalence were calculated using multivariate logistic regression and restricted cubic spline models. The mean daily water intake, turnover and deficit were 2799 ml, 3290 ml and –15 %, respectively. CKD prevalence was 6·3 %. After adjusting for lifestyle and urine and serum osmolality, the fourth water deficit quartile was inversely associated with CKD prevalence when compared with the first quartile (OR, 0·71; 95 % CI, 0·51, 0·98). In the spline analysis, the water deficit at which the OR for CKD prevalence plateaued was approximately –30 % to 0 %. Water deficit had an L-shaped association with CKD prevalence independent of urine and serum osmolality, highlighting the importance of assessing water intake relative to dietary needs. These findings may assist the development of water requirements.

Different starch-to-protein ratios were compared among neutered and spayed domiciled cats. Male and female obese and non-obese cats were fed kibble diets ad libitum for 4 months high in starch (HS (38 % crude protein (CP)): starch 32 %, protein 38 %; DM basis) or high in protein (HP (55 % CP): starch 19 %, protein 55 %) but similar in energy and fat in a crossover design. Physical activity was evaluated using an accelerometer, and body composition (BC), energy expenditure (EE) and water turnover (WT) using the doubly labelled water method. Results were compared in a 2 diet × 2 sex × 2 body condition factorial arrangement. Cats fed the HS (38 % CP) diet maintained a constant body weight, but lean mass (LM) tended to be reduced in female obese but to be increased in male non-obese (P < 0·08) and increased in female non-obese cats (P = 0·01). The HP (55 % CP) diet induced an increase in cat body weight and LM (P < 0·05) without altering BC proportion. EE tended to be higher in males (351 (se 8) kJ/kg0·67/d) than females (330 (se 8) kJ/kg0·67/d; P = 0·06), was unaffected by diet or BC, decreased as age increased (R2 0·44; P < 0·01) and increased as physical activity increased (R2 0·58; P < 0·01). WT was higher for the HP (55 % CP) diet (P < 0·01) and increased with EE (R2 0·65; P < 0·01). The HS (38 % CP) diet favoured body weight control during 4 months of ad libitum feeding. Caution is necessary to balance protein in diets of female obese cats over 5 years, as they may have low energy and food intake, with LM loss.

Hunting with dogs in winter conditions is practised in the Nordic countries. The present study aimed at determining daily energy expenditure (DEE) and body water turnover (BWT) by the doubly labelled water technique in eight hunting dogs (body-weight (BW) range 14–27 kg) working 3 h/d for 3 d ( − 6°C) on ground covered with 20–40 cm of loose snow, to provide information on energy and water requirements. The mean distance run during the hunting period was recorded by the global positioning system and averaged 19·4 km/d. DEE increased with increasing BW (P < 0·001) and varied between 7·20 and 16·6 MJ/d (mean 11·0 MJ/d) corresponding to 950–1350 kJ/kg BW0·75 per d (mean 1170 kJ/kg BW0·75 per d). The larger dogs tended to run longer than the smaller dogs and therefore spent more energy per kg BW0·75 but not significantly (P>0·05). DEE values determined were close to the values measured for hunting dogs running for 3 h/d in hot climates, suggesting that climate within the range of the two studies has little impact on energy expenditure per h running activity. Compared with the work of sled dogs per km travelled running on a track, the work performed by the hunting dogs was suggested to be higher when running in a loose snow layer. However, DEE was much lower because sled dogs ran for a longer distance each day. Mean BWT was 217 ml/kg BW0·75 or 19 ml/kJ metabolisable energy.