Regulation of Energy Balance by Dietary Protein

Zapata, Rizaldy C.

Regulation of Energy Balance by Dietary Protein

dc.contributor.advisor	Chelikani, Prasanth K.
dc.contributor.author	Zapata, Rizaldy C.
dc.contributor.committeemember	Ambrose, D. J.
dc.contributor.committeemember	Banse, Heidi E.
dc.contributor.committeemember	McMillan, Chantal J.
dc.contributor.committeemember	Vijayan, Mathilakath Madathil
dc.contributor.committeemember	Morrison, Christopher David
dc.date	2018-11
dc.date.accessioned	2018-08-21T14:39:20Z
dc.date.available	2018-08-21T14:39:20Z
dc.date.issued	2018-08-16
dc.description.abstract	The protein leverage hypothesis posits that protein restriction triggers a compensatory hyperphagia to facilitate the acquirement of the animal's protein needs whereas protein excess elicit hypophagia as the animal's protein requirement is met at a lesser calorie intake. However, the effects of dietary protein on energy expenditure and the underlying mechanisms are not well-established. Moreover, the domestic cat has potential to more closely model human obesity and diabetes; however, the role of dietary protein in the secretion of metabolic hormones has not been well-studied in cats. In this thesis, the effects of protein-restricted diets, tryptophan or histidine-restricted diets, and diets with excess protein on energy intake, energy expenditure, body weight and composition, gut hormones, glucose clearance, key protein and glucose metabolism markers and thermogenesis were determined in rodent models of diet-induced obesity. In addition, the tissue distribution of the transcripts for proglucagon, glucose-dependent insulinotropic peptide, peptide YY and their cognate receptors in feline peripheral tissues and the effects of the consumption of high-protein diets on the concentrations of circulating metabolites and metabolic hormones were determined in lean, overweight and diabetic cats. Using diet-induced obese rats and a clinical population of domestic cats, this work provided important insights on the mechanisms by which dietary protein regulates energy balance. First, moderately restricting dietary protein transiently promoted hyperphagia yet robustly increased energy expenditure. Second, tryptophan restriction partially recapitulates the age-dependent effects of moderate protein restriction on energy intake and expenditure. Third, the protein source has a significant contribution on the hypophagic and thermogenic effects of high-protein diets, with the increased PYY signaling and reduced diet preference mediating this reduction in energy intake, but not thermogenesis. Finally, although there were inherent differences in plasma concentrations of metabolic hormones between lean, overweight and diabetic cats, protein consumption alone did not alter weight or the secretion of these hormones. Collectively, dietary protein greatly influences energy balance in rodent models of human obesity, but has minimal impact in domestic cats.	en_US
dc.identifier.citation	Zapata, R. C. (2018). Regulation of Energy Balance by Dietary Protein (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/32820	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/32820
dc.identifier.uri	http://hdl.handle.net/1880/107640
dc.language.iso	eng
dc.publisher.faculty	Graduate Studies
dc.publisher.faculty	Veterinary Medicine
dc.publisher.institution	University of Calgary	en
dc.publisher.place	Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	energy balance
dc.subject	protein restriction
dc.subject	high protein diets
dc.subject	whey proteins
dc.subject	lactalbumin
dc.subject	lactoferrin
dc.subject	peptide YY
dc.subject	domestic cats
dc.subject	fibroblast growth factor 21
dc.subject	protein leverage hypothesis
dc.subject	tryptophan
dc.subject	histidine
dc.subject	energy expenditure
dc.subject.classification	Animal Physiology	en_US
dc.subject.classification	Veterinary Science	en_US
dc.subject.classification	Nutrition	en_US
dc.title	Regulation of Energy Balance by Dietary Protein
dc.type	doctoral thesis
thesis.degree.grantor	University of Calgary
thesis.degree.name	Doctor of Philosophy (PhD)
ucalgary.item.requestcopy	true