![[Feedback]](/icons/banner/feedbackACT.gif){kind=icon}
![[For Subscribers]](/icons/banner/subscriberACT.gif){kind=icon}
![[Archive]](/icons/banner/archiveACT.gif){kind=icon}
![[Search]](/icons/banner/searchACT.gif){kind=icon}
![[Contents]](/icons/banner/tocACT.gif){kind=icon}
|
|
|
|
|
||
National Veterinary School of Nantes, Laboratory of Nutrition and Endocrinology, Nantes, France;
* Faculty of Veterinary Medicine, Animal Nutrition Unit, Liège, Belgium and
Centre de Recherche de Royal Canin, Aimargues, France
3To whom correspondence should be addressed. E-mail: pnguyen{at}vet-nantes.fr.
KEY WORDS: • obesity • body composition • energy expenditure • protein turnover • cats
EXPANDED ABSTRACT
Excess body weight and obesity, two common problems in household cats, seem to have become even more frequent in last decades (1). Because feline obesity increases the risk of diabetes mellitus, nonparasitic skin diseases, lameness, and hepatic lipidosis as well as reduces life expectancy (1,2), prevention and treatment are of the utmost importance to the well-being and health of these animals.
Weight reduction is usually obtained by restricting energy intake. Cats, as true carnivores, are unable to adapt their metabolism to low nitrogen intake (3). Hepatic lipidosis, another concern of weight loss programs, can be avoided by reducing energy intake moderately and maintaining high protein intake (4).
In humans (5), mice (6) and dogs (7), weight-loss programs have resulted in lower energy expenditure related to a decrease in metabolic rate, lean body mass and physical activity. In humans, lean tissue loss is greater after severe than after moderate energy restriction (8). Higher protein intake can help prevent or at least minimize lean body mass loss in obese humans (9) as well as in obese dogs (10).
The purpose of this study was to assess the influence of weight loss on body composition, energy expenditure and protein turnover rate and then compare the effects on these parameters of two diets differing mainly in protein content.
 |
MATERIALS AND METHODS |
|---|
 TOP MATERIALS AND METHODS RESULTSDISCUSSIONLITERATURE CITED |
|---|
Seven neutered, domestic short-haired cats (1 female, 6 males) were used in a 21-wk study. The animals were group-housed in pens and maintained on a 12-h light/dark cycle at 20–24°C. Experimental protocols adhered to European Union guidelines and were approved by the Animal Use and Care Advisory Committee of Nantes.
The mean age at the beginning of the study was 6.2 ± 0.7 y (3.2–8.6 y) (Table 1), and all animals had been obese for at least 1 y. The degree of obesity was assessed by body condition scoring (BCS) on a 1-to-5 scale (11). Except for obesity, all animals were healthy according to clinical examination, serum chemistry, urinalysis and hormonal profiles. Target (final) body weights (BW) were estimated on the basis of values for cats in optimal condition (BCS = 3) and of the same body size and shape. Mean estimated excess BW at the beginning of the study was 35 ± 2% (27–44%).
|
Animals were then allotted into two groups (A and B) and fed either an experimental high-protein diet (diet A, four cats) or a commercial obesity diet [diet B (Hill’s Feline r/d, Topeka, KS), three cats] (see Table 1).
Initially, each group A cat received the same daily amount as the amount of food consumed during baseline. A transition was ensured for 1 wk before diet A was given exclusively. In the third wk, the food allowance was reduced by 10%. The same protocol was used for group B. However, because diet A was more energy dense than diet B, the food allowance was adjusted by a ratio [diet A energy content/diet B energy content] to provide similar energy restriction. After 4 wk on the weight loss program, food allowance was adjusted progressively and individually to obtain a BW loss rate of 1–2% per wk.
The diets were continued until the cats reached target BW (Table 1), as previously defined. Individual food consumption was recorded daily, and water was provided ad libitum.
Food energy value was determined for each cat using the AAFCO procedure (12).
Measurements
Biometrics and clinical evaluation.
BW and BCS were recorded weekly. The average weekly BW loss rate (r, in %/wk) was calculated as follows:
 |
where [wk nb] is the number of weeks needed to reach target BW.
Body composition. Total body water was measured by isotopic dilution of 2H2O. On the day of the study, 12-h food-deprived cats were placed in individual cages for water restriction and body water equilibration from 2 h before to 3 h after tracer injection. Cats were injected subcutaneously (1.50 g/kg BW) with physiological saline 2H2O (99.9% 2H/H; Leman, Saint-Quentin-en-Yvelines, France). Blood samples were collected from the jugular vein (5 mL) before and 3 h after tracer injection. Deuterium was assayed by Fourier-transform infrared spectroscopy (13).
Total body water and fat-free mass (FFM in kg) were calculated as previously described (14). FFM was corrected to take into account the lowering effect of proton exchange between water and organic compounds in the deuterium oxide dilution pool (13). Body fat content was calculated from BW and FFM.
Energy expenditure. Resting energy expenditure (REE) was assessed four times (before and after weight loss and at two intermediate points) from continuous measurement of CO2 production and O2 consumption, as previously described (15). Daily REE [in kJ/(kg BW·d) or in kJ/(kg FFM0.89·d)] was extrapolated from 2- to 4-h measurements (15).
Leucine fluxes. As previously described (16), the 13C-leucine kinetic method was used to assess protein fluxes in overnight food-deprived animals, before and at the end of the weight-loss period. Briefly, cats underwent a 3-h infusion of NaH13CO3 [3 µmol/(kg·h) after a priming dose of 6 µmol/kg] to assess CO2 production, followed immediately by a 3-h intravenous infusion of L-[1-13C]leucine [10 µmol/(kg·h) after a priming dose of 15 µmol/kg] to assess leucine appearance rate (RaLeu), oxidation (OxLeu) and nonoxidative leucine disposal (NOLD), expressed as µmol/(kg·h).
Statistical analysis
Data were analyzed by repeated-measures ANOVA, using either one factor (diet) or two factors (time and diet). All statistical calculations were performed with Superanova software (Abacus Concepts, Berkeley, CA). A value of P 
0.05 was considered as significant. Results are expressed as the means ± SEM.
|
RESULTS |
|---|
|
TOPMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
Body weight and BCS (Table 1) decreased significantly during the weight-loss period (P < 0.001) without a diet effect, as did fat mass and FFM (P < 0.001). Cats remained clinically healthy, and biochemical and hormonal analyses were not suggestive of metabolic disorders.
As indicated above, food allowance was adjusted to obtain a BW loss rate of 1–2% per wk. Overall mean energy consumption during the weight-loss period was 169 ± 9 kJ ME/(kg target BW·d) (157 ± 13 and 185 ± 5 in groups A and B, respectively, NS), that is, 66 ± 4% (62 ± 5 and 74 ± 2%, NS) of the assumed energy requirement for adult cats in optimal body condition [(250 kJ ME/(kg BW·d)] (17).
Changes in energy expenditure
Mean extrapolated daily REE (n = 7) was 124 ± 4 kJ/(kg BW·d) and 218 ± 5 kJ/(kg FFM0.89·d). Differences between groups were not significant. REE expressed by kg BW increased as BW and body fat content decreased (P < 0.001), which explains why no significant change in REE was observed over the study when expressed on a FFM basis.
Leucine kinetics
A steady state was observed over the last 60 min of each isotope infusion in 13C-enrichments of plasma KIC and breath CO2. Leucine kinetic variables RaLeu, OxLeu and NOLD did not change significantly during the experimental period and showed no diet effect. However, OxLeu tended to increase at the end of the weight-loss period (P < 0.08) and to be higher in group B (P < 0.09).
|
DISCUSSION |
|---|
|
TOPMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
High-protein diets have been shown to minimize lean body mass loss in humans (9) and dogs (22). In our study, small sample size and the modest difference in protein content between diets (30.4 and 34.5 g CP/MJ ME) may explain that no significant difference was observed between groups. In a previous study, an 18.1% BW loss (8.2% FFM and 90.5% fat) was obtained in 18 wk using a diet containing 29.2 g CP/MJ ME (18) (i.e., a mean weekly BW loss of 1.1%). In our study, cats fed a slightly higher level of protein lost 26% of initial BW in 19 wk (24% FFM and 76% fat) (i.e., a mean weekly loss of 1.6%). This supports in cats the concept developed in humans (8), that loss of lean tissue becomes greater as weight loss rate increases.
In other species, the decrease in energy expenditure correlates positively with the degree of energy restriction. This can be attributed to a decrease in metabolic rate, a loss of lean body mass (which has a much higher metabolic rate than adipose tissue), and a decrease in physical activity. Diet may also affect adaptation to energy restriction. High-protein, low-glycemic-index diets enhanced fat tissue oxidation and the conservation of muscle mass (27). Maintaining high protein intake, as in our study, reduces the decrease in energy expenditure during energy restriction (28).
The cats used in this study had been obese for more than 1 yr. Their metabolic rate was probably already low, and living in a cattery could have made them lazy. Thus, energy restriction would not have induced a significant decrease in activity level. The relatively high protein level of the diets could also have contributed to maintaining energy expenditure, given that wasting is high when protein is used as a source of energy.
Because leucine kinetic variables at steady state can be converted to protein fluxes on the basis of commonly accepted assumptions (29), the 13C-leucine method was used in our study to assess the effects of weight loss on postabsorptive protein metabolism. To our knowledge this method has not been used previously in cats. Our results are consistent with those previously reported for other species, especially dogs (30).
No significant differences in leucine appearance rate (RaLeu) and utilization for protein synthesis (NOLD) were observed before and after weight loss or between diets, which is consistent with previous human (31,32) and dog studies (30). Only a nonsignificant increase in leucine oxidation rate (OxLeu) was observed at the end of the weight-loss period. In a recent study, weight loss induced no significant changes in leucine kinetics variables in obese women (31). In some human studies, high protein intakes were associated with a decrease in postabsorptive leucine oxidation rate compared to intake close to the requirement (33). In our study, both weight loss and protein intake factors were involved. Because group size was limited in this first application of the 13C-leucine method to cats, our results do not allow definitive conclusions. However, this method would seem useful to assess protein metabolism in various situations in cats.
|
ACKNOWLEDGMENTS |
|---|
|
FOOTNOTES |
|---|
2 Supported, in part, by Royal Canin S.A.
4 Abbreviations used: BCS, body condition score; BF%, body fat content; BW, body weight; CP, crude protein; FFM, free-fat mass; ME, metabolizable energy; NOLD, nonoxidative leucine disposal; OxLeu, leucine oxidation rate; RaLeu, leucine appearance rate; REE, resting energy expenditure.
5 Diet A contained poultry by-product meal, corn gluten meal, cellulose, rice gluten meal, beet pulp, barley, poultry oil, poultry liver digest, psyllium, brewer’s yeast, fructo-oligosaccharides, L-carnitine, minerals and vitamins.
6 Diet B contained poultry by-product meal, ground corn, powdered cellulose, corn gluten meal, chicken liver digest, vegetable oil, meat protein isolate, glyceryl monostearate, taurine, L-carnitine, minerals, vitamins, BHT, BHA and ethoxyquin.
|
LITERATURE CITED |
|---|
|
TOPMATERIALS AND METHODSRESULTSDISCUSSIONLITERATURE CITED |
|---|
1. Donoghue, S. & Scarlett, J. M. (1998) Diet and feline obesity. J. Nutr. 128:2776S-2778S.
2. Rand, J. S. & Appleton, D. J. (2001) Feline obesity: causes and consequences. Proceedings of the 19th ACVIM Veterinary Medical Forum 2001:533-535 Denver, CO .
3. Rogers, Q. R. & Morris, J. G. (1982) Do cats really need more protein?. J. Small Anim. Pract. 23:521-532.
4. Biourge, V. C., Massat, B., Groff, J. M., Morris, J. G. & Rogers, Q. R. (1994) Effects of protein, lipid, or carbohydrate supplementation on hepatic lipid accumulation during rapid weight loss in obese cats. Am. J. Vet. Res. 55:1406-1415.[Medline]
5. Foster, G. D., Wadden, T. A., Swain, R. M., Anderson, D. A. & Vogt, R. A. (1999) Changes in resting energy expenditure after weight loss in obese African American and white women. Am. J. Clin. Nutr. 69:13-17.
6. Dulloo, A. G. & Calokatisa, R. (1991) Adaptation to low calorie intake in obese mice: contribution of a metabolic component to diminished energy expenditures during and after weight loss. Int. J. Obes. 15:7-16.[Medline]
7. Pouteau, E., Mariot, S., Martin, L., Dumon, H., Robins, R., Darmaun, D., Naulet, N. & Nguyen, P. (2000) Effect of weight variations (fattening and slimming) on energy expenditure in dogs. J. Vet. Intern. Med. 14:390(abstract).
8. Prentice, A. M., Goldberg, G. R., Jebb, S. A., Black, A. E. & Murgatroyd, P. R. (1991) Physiological responses to slimming. Proc. Nutr. Soc. 50:441-458.[Medline]
9. Wadden, T. A., Stunkard, A. J., Brownell, K. D. & Day, S. C. (1985) A comparison of two very-low-calorie diets: protein-sparing-modified fast versus protein-formula-liquid diet. Am. J. Clin. Nutr. 41:533-539.
10. Hannah, S. S. (1999) Role of dietary protein in weight management. Comp. Cont. Educ. Pract. Vet. 21:32-33.
11. Scarlett, J. M., Donoghue, S., Saidla, J. & Wills, J. (1994) Overweight cats: prevalence and risk factors. Int. J. Obes. Relat. Metab. Disord. 18:S22-S28.
12. Association of American Feed Control Officials (2001) Official Publication 2001 AAFCO, Inc Atlanta, GA.
13. Ferrier, L., Robert, P., Dumon, H., Martin, L. & Nguyen, P. (2002) Evaluation of body composition in dogs by isotopic dilution using a low-cost technique, Fourier-transform infrared spectroscopy. J. Nutr. 132:1725S-1727S.
14. Pouteau, E. B., Mariot, S. M., Martin, L. J., Dumon, H. J., Mabon, F. J., Krempf, M. A., Robins, R. J., Darmaun, D. H., Naulet, N. A. & Nguyen, P. G. (2002) Rate of carbon dioxide production and energy expenditure in fed and food-deprived adult dogs determined by indirect calorimetry and isotopic methods. Am. J. Vet. Res. :(in press).
15. Nguyen, P., Dumon, H., Martin, L., Siliart, B. & Biourge, V. (2002) Energy expenditure and requirement assessed using three different methods in adult cats. J. Anim. Physiol. Anim. Nutr. :(submitted).
16. Humbert, B., Le Bacquer, O., Nguyen, P., Dumon, H. & Darmaun, D. (2001) Protein restriction and dexamethasone as a model of protein hypercatabolism in dogs: effect of glutamine on leucine turnover. Metabolism 50:293-298.[Medline]
17. National Research Council (1978) Nutrient Requirement of Cats 1978 National Academy Press Washington, DC.
18. Butterwick, R. F. & Markwell, P. J. (1996) Changes in the body composition of cats during weight reduction by controlled dietary energy restriction. Vet. Rec. 138:354-357.
19. Center, S. A., Harte, J., Watrous, D., Reynolds, A., Watson, T. D., Markwell, P. J., Millington, D. S., Wood, P. A., Yeager, A. E. & Erb, H. N. (2000) The clinical and metabolic effects of rapid weight loss in obese pet cats and the influence of supplemental oral L-carnitine. J. Vet. Intern. Med. 14:598-608.[Medline]
22. Hannah, S. S. & Laflamme, D. P. (1998) Increased dietary protein spares lean body mass during weight loss in dogs. J. Vet. Int. Med. 12:224.
23. Flynn, M. F., Hardie, E. M. & Armstrong, P. J. (1996) Effect of ovariohysterectomy on maintenance energy requirement in cats. J. Am. Vet. Med. Assoc. 209:1572-1581.[Medline]
27. Pasquali, R., Casimirri, F. & Melchionda, N. (1987) Protein metabolism in obese patients during very low-calorie mixed diets containing different amounts of proteins and carbohydrates. Metabolism 36:1141-1148.[Medline]
28. Whitehead, J. M., McNeill, G. & Smith, J. S. (1996) The effect of protein intake on 24-h energy expenditure during energy restriction. Int. J. Obes. Relat. Metab. Disord. 20:727-732.[Medline]
29. Matthews, D. E., Motil, K. J., Rohrbaugh, D. K., Burke, J. F., Young, V. R. & Bier, D. M. (1980) Measurement of leucine metabolism in man from a primed, continuous infusion of L-[1–13C]leucine. Am. J. Physiol. Endocrinol. Metab. 238:E473-E479.
30. Humbert, B., Bleis, P., Martin, L., Dumon, H., Darmaun, D. & Nguyen, P. (2001) Effects of dietary protein restriction and amino acid deficiency on protein metabolism in dogs. J. Anim. Physiol. Anim. Nutr. 85:255-262.[Medline]
31. Gallagher, D., Kovera, A. J., Clay-Williams, G., Agin, D., Leone, P., Albu, J., Matthews, D. E. & Heymsfield, S. B. (2000) Weight loss in postmenopausal obesity: no adverse alterations in body composition and protein metabolism. Am. J. Physiol. Endocrinol. Metab. 279:E124-E131.
32. Pacy, P. J., Price, G. M., Halliday, D., Quevedo, M. R. & Millward, D. J. (1994) Nitrogen homeostasis in man:: 2. The diurnal responses of protein synthesis and degradation and amino acid oxidation to diets with increasing protein intakes. Clin. Sci. 86:103-116.[Medline]
33. Garlick, P. J., McNurlan, M. A. & Ballmer, P. E. (1991) Influence of dietary protein intake on whole-body protein turnover in humans. Diabetes Care 14:1189-1198.[Abstract]
This article has been cited by other articles:
|
|
 |
|
  C. Villaverde, J. J. Ramsey, A. S. Green, D. K. Asami, S. Yoo, and A. J. Fascetti Energy Restriction Results in a Mass-Adjusted Decrease in Energy Expenditure in Cats That Is Maintained after Weight Regain J. Nutr., May 1, 2008; 138(5): 856 - 860. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Hoenig, K. Thomaseth, M. Waldron, and D. C. Ferguson Insulin sensitivity, fat distribution, and adipocytokine response to different diets in lean and obese cats before and after weight loss Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2007; 292(1): R227 - R234. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. J. Ramsey and K. Hagopian Energy Expenditure and Restriction of Energy Intake: Could Energy Restriction Alter Energy Expenditure in Companion Animals? J. Nutr., July 1, 2006; 136(7): 1958S - 1966S. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
P. Nguyen, V. Leray, H. Dumon, L. Martin, B. Siliart, M. Diez, and V. Biourge High Protein Intake Affects Lean Body Mass but Not Energy Expenditure in Nonobese Neutered Cats J. Nutr., August 1, 2004; 134(8): 2084S - 2086S. [Full Text] [PDF]
|
|
|
|
|
|
G. Blanchard, P. Nguyen, C. Gayet, I. Leriche, B. Siliart, and B.-M. Paragon Rapid Weight Loss with a High-Protein Low-Energy Diet Allows the Recovery of Ideal Body Composition and Insulin Sensitivity in Obese Dogs J. Nutr., August 1, 2004; 134(8): 2148S - 2150S. [Full Text] [PDF]
|
|
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
