Introduction
Research in feline nutrition has largely focused on the effects of nutrient distribution and density on feline physiology, while a derth of work has been paid to feeding management, such as feeding frequency. A recent consensus statement, which focused on reducing behavioural problems and stress in cats, recommended that cats’ daily food allowances be divided into multiple small meals fed throughout the day [1]. There is, however, a lack of empirical evidence to support multiple meal feeding for the indoor pet cat to help support a healthy body composition and body weight (BW).
Numerous factors affect energy intake and utilization and excess intake creates positive energy balance and deposition of adipose tissue [2-4]. Obesity, which largely affects middle-aged cats [5-9], is the most common nutritional problem in cats and is considered to be a low-grade inflammatory disease [2-4], predisposing cats to many adverse health conditions [7, 10, 11]. Ad libitum feeding and feeding frequently, which cannot be teased apart in epidemiological research, have been reported to be risk factors for weight gain and adverse health conditions by some [12-14], but not by others [5, 6, 8, 15, 16]. Courcier et al. [9] reported that cats fed twice daily were more likely to be obese than cats fed ad libitum [17]. In a recent review investigating meal frequency in human and animal (mouse, rat, calf, cow, horse, and fish) studies, it was suggested that increased eating frequency may not assist in reducing energy intake or improving BW [18]. However, cats had lesser plasma concentrations of orexigenic ghrelin, and greater concentrations of anorexigenic leptin when fed four times daily compared to twice daily [19]. Cats fed two or four times daily also had greater voluntary physical activity than cats fed once per day [20, 21]. LeBlanc and Diamond reported that increased meal frequency was related to greater postprandial thermogenesis [22] and this was likely related to increased anticipation of feeding [22]. Though energy expenditure (EE) was not affected by intermittent fasting in humans, the observed decrease in respiratory quotient (RQ) is suggestive of enhanced fat oxidation [23, 24]. To the authors’ knowledge, research examining the effects of feeding frequency on energetics and macronutrient utilization have not been performed.
Meal frequency may also affect protein metabolism and lean body mass [LBM]. In neonatal animal models, including rats and piglets, intermittent fasting has resulted in greater protein synthesis [25-31]. Gazzaneo et al. [32] suggested that compared to continuous feeding, intermittent feeding enhances lean tissue accumulation by promoting a greater and more rapid postprandial amino acid (AA) and insulin response, initiating protein synthesis. Similarly, postprandial AA concentrations increased more when resistance-trained men ate less frequently throughout the day [33]. Geriatric cats are prone to loss of LBM and BW as a result of age-related changes of energy metabolism [34] and could benefit from feeding management practices that increase lean tissue maintenance. Lean body mass loss, sarcopenia, is a natural process of aging, which occurs in the absence of clinical disease [35]. By age 15, cats may lose one-third of the LBM that was present between the ages of 1 to 7 years [36]. Increasing protein synthesis and LBM by changing the feeding regimen of older cats could help mitigate the incidence of sarcopenia and improve overall functionality.
The objectives of this research were to investigate the effects of feeding frequency, one compared to four meals per day, on fasting and postprandial serum concentrations of appetite-regulating hormones (glucagon-like protein-1 (GLP-1), gastric inhibitory protein (GIP), ghrelin, leptin and peptide YY (PYY), glucose, insulin, AA, fasting and postprandial EE and RQ, and voluntary physical activity in domestic cats.