Influence of a high-protein diet on energy balance in obese cats allowed ad libitum access to food

High starch intake favours body weight control in neutered and spayed cats living in homes fed ad libitum

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 (R 2 0·44; P < 0·01) and increased as physical activity increased (R 2 0·58; P < 0·01). WT was higher for the HP (55 % CP) diet (P < 0·01) and increased with EE (R 2 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.

Identifying the target population and preventive strategies to combat feline obesity

Feline obesity continues to be a priority health and welfare issue. Most research surrounding obesity currently focuses on obesity treatment. However, treatment for feline obesity is slow, often unsuccessful and not without consequences. Identifying high-risk populations for obesity onset is crucial for developing and implementing preventive strategies. This review identifies post-gonadectomy kittens aged 5-12 months as the primary target population for obesity prevention in domestic cats and highlights dietary and feeding management strategies to be implemented for obesity prevention.

Influence of high-protein and high-carbohydrate diets on serum lipid and fructosamine concentrations in healthy cats

OBJECTIVES

The aim of this study was to determine whether high-protein and high-carbohydrate diets exert differential effects on serum cholesterol, triglyceride and fructosamine concentrations in healthy cats.

METHODS

A randomised, crossover diet trial was performed in 35 healthy shelter cats. Following baseline health assessments, cats were randomised into groups receiving either a high-protein or high-carbohydrate diet for 4 weeks. The cats were then fed a washout diet for 4 weeks before being transitioned to whichever of the two studied diets they had not yet received. Fasting serum cholesterol, triglyceride and fructosamine concentrations were determined at the end of each 4-week diet period.

RESULTS

Cats on the high-carbohydrate diet had significantly lower serum cholesterol (P <0.001) concentrations compared with baseline measurements. Cats on the high-protein diet had significantly higher serum cholesterol (P <0.001) and triglyceride (P <0.001) concentrations, yet lower fructosamine (P <0.001) concentrations compared with baseline measurements. In contrast, overweight cats (body condition score [BCS] >5) had lower cholesterol (P = 0.007) and triglyceride (P = 0.032) concentrations on the high-protein diet than cats within other BCS groups.

CONCLUSIONS AND RELEVANCE

Diets higher in protein and lower in carbohydrates appear beneficial for short-term glucose control in healthy cats. A high-protein diet was associated with significantly elevated cholesterol and triglyceride concentrations in healthy cats, even though the increase was significantly less pronounced in cats with a BCS >5. This finding suggests that overweight cats process high-protein diets, cholesterol and triglycerides differently than leaner cats.

Properties of Foods That Impact Appetite Regulation in Cats

Overweight and obesity are common in global pet cat populations which makes it important to understand how properties of food affect appetite (food motivation). In four experiments, we studied this by using a model of operant conditioning for assessing appetite in which cats could press a lever for food rewards. There was no effect of protein status on motivation for protein, when evaluated in a cross-over design with cats receiving low protein (LP) or high protein (HP) foods for 14 days. Cats obtained similar numbers of HP and LP rewards, irrespective of whether their daily food was HP or LP (mixed-effects model, P = 0.550 for food × reward, P = 0.151 for reward). High dietary protein reduced food motivation when we regressed protein levels in 12 commercial foods (12.0 to 27.4 g crude protein/MJ metabolizable energy; P = 0.022) fed for 2 days and tested at 5 h postprandially on the third day whereas fiber levels were without effect (3.8 to 17.8 g non-starch polysaccharides/MJ; P = 0.992). Dietary fiber may reduce appetite depending on its physicochemical properties and we tested the effect of a gelling fiber (alginate), viscous fiber (psyllium) and a fermentable fiber (inulin). Cats received test foods as well as control foods for 3 days and were tested on the third day at 3 h (alginate), 5 h (psyllium) or 8 h (inulin) postprandially. Enriching the food with alginate (P = 0.379) or psyllium (P = 0.153) did not affect the number of rewards obtained, but the feeding of the inulin-enriched food did make the cats obtain fewer rewards than when they received the control food (P = 0.001). Finally, cooking or grinding of dietary meat increased the number of rewards obtained by cats, on day 3 at 3 h postprandial, without evidence for additive effects of these treatments (P = 0.014 for grinding × cooking). This study shows that dietary content of protein or fiber, and the grinding or cooking of meat, all affect appetite in cats as expected, though some predicted effects remained undetected and clearly details regarding food properties matter. These and future findings can guide the designing of foods that promote satiety and prevent over-eating in meal-fed cats.

Understanding the Nutritional Needs of Healthy Cats and Those with Diet-Sensitive Conditions

Diets for cats must provide complete nutrition and meet the needs of the individual patient. There is no single diet that is perfect for all cats, and veterinarians must consider the needs of the cat as well as the preferences of the owners when making dietary recommendations. This article focuses on the interface between animal factors and nutritional needs in cats and is divided into 3 sections. Section 1 addresses the dietary needs of healthy cats, including differences among life stages. Section 2 addresses common myths regarding feline nutrition. Section 3 addresses common nutrient-sensitive conditions in cats, including sarcopenia of aging.

Impact of dietary macronutrient profile on feline body weight is not consistent with the protein leverage hypothesis

The protein leverage hypothesis proposes that the need to prioritise protein intake drives excess energy intake (EI) when the dietary ratio of protein to fat and carbohydrate is reduced. We hypothesised that cats may become prone to overconsuming energy content when moderate protein diets were offered, and considered the potential influence of fat and carbohydrate on intake. To determine the effect of dietary protein and macronutrient profile (MNP) on EI, weight and body composition, cats (1-4 years) were offered food in excess of energy requirements (ER). A total of six diets were formulated, containing moderate (approximately 7 % w/w; approximately 22 % metabolisable energy (ME)) or high (approximately 10 % w/w; approximately 46 % ME) protein and varying levels of carbohydrate and fat. For 4 weeks, 120 cats were offered 100 % of their individual ER of a diet at the MNP selected by adult cats (50:40:10 protein energy ratio:fat energy ratio:carbohydrate energy ratio). EI, body weight (BW), body composition, activity and palatability were measured. Subsequently, cats were offered one of the six diets at 200 % of their individual ER for 4 weeks when measurements were repeated. Cats offered excess high protein diets had higher EI (kJ/kg) throughout, but at 4 weeks BW was not significantly different to baseline. Cats offered excess moderate protein diets reduced EI and gradually lost weight (average loss of 0·358 (99 % CI 0·388, 0·328) kg), irrespective of fat:carbohydrate and initial palatability. The data do not support the protein leverage hypothesis. Furthermore, cats were able to adapt intake of a wet diet with high protein in an overfeeding environment within 28 d.

Overweight in adult cats: a cross-sectional study

Background

Overweight in cats is a major risk factor for diabetes mellitus and has also been associated with other disorders. Overweight and obesity are believed to be increasing problems in cats, as is currently seen in people, with important health consequences. The objectives of the present study were to determine the prevalence of overweight in cats from two different cohorts in a cross-sectional study design and to assess associations between overweight and diagnoses, and between overweight and demographic and environmental factors. Data were obtained from medical records for cats (n = 1072) visiting an academic medical center during 2013–2015, and from a questionnaire on insured cats (n = 1665). From the medical records, information on body condition score, breed, age, sex, neutering status, and diagnosis was obtained. The questionnaire included questions relating to the cat’s body condition, breed, age, sex, neutering status, outdoor access, activity level, and diet. Data were analyzed by multivariable logistic regression.

Results

The prevalence of overweight was 45% in the medical records cohort and 22% in the questionnaire cohort, where owners judged their pet’s body condition. Overweight cats in the medical records cohort were more likely to be diagnosed with lower urinary tract disease, diabetes mellitus, respiratory disease, skin disorders, locomotor disease, and trauma. Eating predominantly dry food, being a greedy eater, and inactivity were factors associated with an increased risk of overweight in the final model in the questionnaire cohort. In both cohorts, the Birman and Persian breeds, and geriatric cats, were less likely to be overweight, and male cats were more likely to be overweight.

Conclusions

The prevalence of overweight cats (45%) as assessed by trained personnel was high and in the same range as previously reported. Birman and Persian cats had a lower risk of overweight. The association with dry food found in adult, neutered cats is potentially important because this type of food is commonly fed to cats worldwide, and warrants further attention. Drawbacks related to the study design need to be acknowledged when interpreting the results, such as a potential for selection bias for cats visiting an animal hospital, and an information bias for questionnaire data. The high occurrence of overweight in cats needs to be addressed because it negatively affects their health.

Electronic supplementary material

The online version of this article (10.1186/s13028-018-0359-7) contains supplementary material, which is available to authorized users.

Metabolic response to three different diets in lean cats and cats predisposed to overweight

Background

The existence of a genetic predisposition to obesity is commonly recognized in humans and rodents. Recently, a link between genetics and overweight was shown in cats. The goal of this study was to identify the effect of diet composition on plasma levels of glucose, insulin, free fatty acids and triglycerides in cats receiving different diets (high-carbohydrate, high-fat and high-protein diets).

Results

Insulin and leptin concentrations were significantly correlated with phenotype. Insulin levels were lower, whereas leptin levels were higher in cats predisposed to overweight. The other blood parameters were not correlated with phenotype. Intake of the high-carbohydrate diet resulted in higher insulin concentrations compared with the two other diets. Insulin levels were within the values described for non-obese cats in previous studies.

Conclusions

There was no difference in metabolic response between the two groups. As the high-carbohydrate diet led to the highest insulin blood concentrations, it might be useful to avoid such diets in cats predisposed to overweight. In addition, even cats with genetically linked obesity can regain insulin sensitivity after weight loss.

Differential circulating concentrations of adipokines, glucagon and adropin in a clinical population of lean, overweight and diabetic cats

BACKGROUND

Dyslipidemia, dysregulated adipokine secretion and alteration in glucagon and adropin concentrations are important obesity-related factors in the pathophysiology of human Type 2 diabetes; however, their roles in the pathophysiology of feline diabetes mellitus are relatively unknown. Here, we determined the concentrations of circulating leptin, adiponectin, pro-inflammatory cytokines, glucagon, adropin, triglycerides, and cholesterol, in non-diabetic lean and overweight cats and newly diagnosed diabetic cats. Client-owned cats were recruited and assigned into 3 study groups: lean, overweight and diabetic. Fasting blood samples were analyzed in lean, overweight and diabetic cats at baseline and 4 weeks after consumption of high protein/low carbohydrate standardized diet.

RESULTS

Serum concentrations of triglycerides were greater in diabetics at baseline and were increased in both diabetic and overweight cats at 4 weeks. Plasma leptin concentrations were greater in diabetic and overweight at baseline and 4 weeks, whereas adiponectin was lower in diabetics compared to lean and overweight cats at baseline and 4 weeks. Diabetics had greater baseline plasma glucagon concentrations compared to lean, lower adropin than overweight at 4 weeks, and lower IL-12 concentrations at 4 weeks than baseline.

CONCLUSIONS

Our results suggest that feline obesity and diabetes mellitus are characterized by hypertriglyceridemia and hyperleptinemia; however, diabetic cats have significantly lower adiponectin and adropin compared to overweight cats. Thus, despite having similar body condition, overweight and diabetic cats have differential circulating concentrations of adiponectin and adropin.

Translational value of animal models of obesity-Focus on dogs and cats

A prolonged imbalance between a relative increase in energy intake over a decrease in energy expenditure results in the development of obesity; extended periods of a positive energy balance eventually lead to the accumulation of abnormally high amounts of fat in adipose tissue but also in other organs. Obesity is considered a clinical state of impaired general heath in which the excessive increase in adipose tissue mass may be associated with metabolic disorders such as type 2 diabetes mellitus, hyperlipidemia, hypertension and cardiovascular diseases. This review discusses briefly the use of animal models for the study of obesity and its comorbidities. Generally, most studies are performed with rodents, such as diet induced obesity and genetic models. Here, we focus specifically on two different species, namely dogs and cats. Obese dogs and cats show many features of human obesity. Interestingly, however, dogs and cats differ from each other in certain aspects because even though obese dogs may become insulin resistant, this does not result in the development of diabetes mellitus. In fact, diabetes in dogs is typically not associated with obesity because dogs present a type 1 diabetes-like syndrome. On the other hand, obese cats often develop diabetes mellitus which shares many features with human type 2 diabetes; feline and human diabetes are similar in respect to their pathophysiology, underlying risk factors and treatment strategies. Our review discusses genetic and endocrine factors in obesity, discusses obesity induced changes in lipid metabolism and includes some recent findings on the role of gut microbiota in obesity. Compared to research in rodent models, the array of available techniques and tools is unfortunately still rather limited in dogs and cats. Hence, even though physiological and pathophysiological phenomena are well described in dogs and cats, the underlying mechanisms are often not known and studies investigating causality specifically are scarce.

Macronutrients in feline health

Dietary macronutrients include protein, fat, and carbohydrates. Current nutritional recommendations establish minimums but not maximums for protein and fat but not for carbohydrates; thus, commercial feline maintenance diets have a wide range of macronutrient distribution depending on manufacturer, ingredients, and processing. There is growing interest and discussion, however, in defining the ideal macronutrient composition of feline diets to maximize longevity and health. Current recommendations should be tailored to each patient based on age, body condition, presence of muscle mass atrophy, and the presence of disease.

Influence of dietary protein level on body composition and energy expenditure in calorically restricted overweight cats

High-protein (HP) diets help prevent loss of lean mass in calorie-restricted (CR) cats. However, it is not entirely known whether these diets also induce changes of energy expenditure during periods of CR. To investigate this issue, sixteen overweight cats were fed either a high-protein [(HP), 54.2% of metabolizable energy (ME)] or a moderate-protein [(MP), 31.5% of ME] diet at 70% of their maintenance energy intakes for 8 weeks, and energy expenditure, energy intake, body weight and composition, and serum metabolites and hormones were measured. While both groups of cats lost weight at a similar rate, only cats eating the HP diet maintained lean mass during weight loss. Indirect respiration calorimetry measurements revealed that both total and resting energy expenditure (kcal/d) significantly decreased during weight loss for both treatment groups. However, only cats eating the MP diet exhibited significant decreases of total and resting energy expenditures after energy expenditure was normalized for body weight or lean mass. Results from this study suggest that in addition to sparing the loss of lean mass, feeding HP diets to overweight cats in restricted amounts may be beneficial for preventing or minimizing decreases of mass-adjusted energy expenditure during weight loss.

Acute hormonal response to glucose, lipids and arginine infusion in overweight cats

In cats, the incidence of obesity and diabetes is increasing, and little is known about specific aspects of the endocrine control of food intake in this species. Recent data suggest that ghrelin has an important role in the control of insulin secretion and vice versa, but this role has never been demonstrated in cats. Here we aimed to improve our understanding about the relationship between insulin, amylin and ghrelin secretion in response to a nutrient load in overweight cats. After a 16 h fast, weekly, six overweight male cats underwent randomly one of the four testing sessions: saline, glucose, arginine and TAG. All solutions were isoenergetic and isovolumic, and were injected intravenously as a bolus. Glucose, insulin, acylated ghrelin (AG), amylin and prolactin were assayed in plasma before and 10, 20, 40, 60, 80 and 100 min after the nutrient load. A linear mixed-effects model was used to assess the effect of bolus and time on the parameters. A parenteral bolus of glucose or arginine increased insulin and ghrelin concentrations in cats. Except for with the TAG bolus, no suppression of ghrelin was observed. The absence of AG suppression after the intravenous load of arginine and glucose may suggest: (1) that some nutrients do not promote satiation in overweight cats; or that (2) AG may be involved in non-homeostatic consumption mechanisms. However, the role of ghrelin in food reward remains to be assessed in cats.

Effect of dietary carbohydrate, fat, and protein on postprandial glycemia and energy intake in cats

BACKGROUND

Reducing carbohydrate intake is recommended in diabetic cats and might also be useful in some healthy cats to decrease diabetes risk.

OBJECTIVE

To compare postprandial glucose and insulin concentrations and energy intakes between cats fed diets high in protein, fat, or carbohydrate.

ANIMALS

Twenty-four lean cats with normal glucose tolerance.

METHODS

In a prospective randomized study, each of 3 matched groups (n = 8) received a different test diet for 5 weeks. Diets were high in either protein (46% of metabolizable energy [ME]), fat (47% ME), or carbohydrate (47% ME). Glucose and insulin were measured during glucose tolerance, ad libitum, and meal-feeding tests.

RESULTS

During ad libitum feeding, cats fed the high-carbohydrate diet consumed 25% and 18% more carbohydrate than cats fed diets high in fat and protein, respectively, and energy intake was highest when the high-fat and high-protein diets were fed. Regardless of the feeding pattern, cats fed the high-carbohydrate diet had 10-31% higher peak and mean glucose compared with both other diets; peak glucose in some cats reached 10.4 mmol/L (188 mg/dL) in cats fed 47% ME carbohydrate and 9.0 mmol/L (162 mg/dL) in cats fed 23% ME.

CONCLUSIONS AND CLINICAL IMPORTANCE

High-carbohydrate diets increase postprandial glycemia in healthy cats compared with diets high in fat or protein, although energy intake is lower. Avoidance of high- and moderate-carbohydrate diets can be advantageous in cats at risk of diabetes. Maintenance energy requirements should be fed to prevent weight gain when switching to lower carbohydrate diets.

Postprandial glycaemia in cats fed a moderate carbohydrate meal persists for a median of 12 hours--female cats have higher peak glucose concentrations

The postprandial increase in glucose concentration is typically not considered in selecting diets to manage diabetic and pre-diabetic cats. This study describes increases in glucose and insulin concentrations in 24 clinically healthy, neutered adult cats following one meal (59 kcal/kg) of a moderate carbohydrate diet (25% of energy). Median time to return to baseline after feeding for glucose was 12.2 h (1.8-≥24 h) and for insulin was 12.3 h (1.5-≥24 h). Time to return to baseline for glucose was not different between male (10.2 h) and female (17.2 h) cats. There was evidence female cats had a longer return to baseline for insulin (18.9 h versus 9.8 h) and females had higher (0.9 mmol/l difference) peak glucose than males. This demonstrates that the duration of postprandial glycaemia in cats is markedly longer than in dogs and humans, and should be considered when managing diabetic and pre-diabetic cats.

Nutritional care for aging cats and dogs

Veterinarians need to be prepared to provide nutritional advice for healthy pets as well as for pets that are ill. Before instituting a dietary change in any patient, especially an older dog or cat, a nutritional evaluation should be completed. This should include an evaluation of the patient, the current diet, and feeding management. Diets should be appropriate to the unique needs of the individual patient. Many diseases in senior pets are “diet-sensitive” meaning that diet can play a role in managing the effects of the disease. Common examples discussed include cognitive dysfunction of aging, osteoarthritis, and obesity.

Companion Animals Symposium: Obesity in dogs and cats: What is wrong with being fat?

Few diseases in modern pets are diet induced. One possible exception to this is obesity, which is ultimately caused by consuming more calories than needed by the dog or cat. Although fat is the most concentrated and efficiently stored source of calories, and protein least so, an excess of calories from any source will contribute to adiposity. Obesity is an excess of body fat sufficient to result in impairment of health or body function. In people, this is generally recognized as 20 to 25% above ideal BW. This degree of excess is important in dogs as well. A lifelong study in dogs showed that even moderately overweight dogs were at greater risk for earlier morbidity; these dogs required medication for chronic health problems sooner than their lean-fed siblings. The average difference in BW between groups was approximately 25%. Obese cats also face increased health risks, including an increased risk of arthritis, diabetes mellitus, hepatic lipidosis, and early mortality. The risk for development of diabetes increases about 2-fold in overweight cats and about 4-fold [corrected] in obese cats. Altered adipokine secretion appears to be an important mechanism for the link between excess BW and many diseases. Once considered to be physiologically inert, adipose tissue is an active producer of hormones, such as leptin and resistin, and cytokines, including many inflammatory cytokines such as tumor necrosis factor-α, IL-1β and IL-6, and C-reactive protein. The persistent, low-grade inflammation secondary to obesity is thought to play a causal role in chronic diseases such as osteoarthritis, cardiovascular disease, diabetes mellitus, and others. For example, tumor necrosis factor-α alters insulin sensitivity by blocking activation of insulin receptors. In addition, obesity is associated with increased oxidative stress, which also may contribute to obesity-related diseases. Management of obesity involves nutritional modification as well as behavioral modification. Increased protein intake combined with reduced calorie intake facilitates loss of body fat while minimizing loss of lean body mass. Limiting treats to 10% of calorie intake and increasing exercise both aid in successful BW management.