Caloric Dilution Research Articles

Exercise and Caloric Dilution

Exercise and Caloric Dilution

A combined dietary chronic toxicity and two-year carcinogenicity study of (2R,4R)-monatin salt in Sprague–Dawley rats

In a combined chronic toxicity/carcinogenicity study, groups of Crl:CD(SD) rats were fed 0 (2 control groups), 5000, 20,000, or 40,000 ppm (2R,4R)-monatin salt (hereafter “R,R-monatin”) in the diet for up to one year in the chronic toxicity phase and up to two years in the carcinogenicity phase. There were no adverse effects on survival, incidence of palpable masses, neoplasms, organ weights, or ophthalmic examinations. The only notable effect was statistically significantly lower mean body weights and body weight gains in all treated groups generally throughout the study, which were most likely a result of caloric dilution of the test diets. Effects of long-term R,R-monatin ingestion by rats were predominantly focused on the urinary system (i.e., clinical pathology alterations indicative of electrolyte and pH imbalances, increased incidence of renal calculi, mineralization and bone hyperostosis, and increased severity of chronic progressive nephropathy). The no-observed-adverse-effect level (NOAEL) for R,R-monatin from the chronic toxicity phase was 20,000 ppm (equivalent to an exposure level of 1080 mg/kg bw/day for males and 1425 mg/kg/day for females) and from the carcinogenicity phase was 5000 ppm (equivalent to an exposure level of 238 and 302 mg/kg bw/day for males and females, respectively).

A two-year dietary carcinogenicity study of (2R,4R)-monatin salt in mice

Groups of Crl:CD-1 (ICR) mice (60/group/sex) were fed 0 (2 control groups), 5000, 20,000, or 40,000 ppm of enzymatically sourced (2R,4R)-monatin salt (“R,R-monatin”) in the diet for up to two years. There were no adverse effects on survival, incidence of palpable masses and tumors, feed consumption, hematology or serum chemistry parameters, organ weights, or ophthalmic, macroscopic, and microscopic examinations. The only notable effect was statistically significantly lower mean body weights and body weight gains in all treated groups, which generally occurred throughout the study and were most likely a result of caloric dilution of the test diets and not considered adverse. There were no test article-related changes in the incidence or occurrence of neoplastic diseases in mice on this study. The no-observed-effect-level (NOEL) for carcinogenicity of R,R-monatin fed to mice for 24 months was 40,000 ppm, the highest dietary concentration tested, which was equivalent to approximately 6502 and 7996 mg/kg bw/day in males and females, respectively.

Fructose, Obesity, and Related Epidemiology

Fructose occurs in fruits, vegetable, and sweetened drinks alongside glucose as free sugars or bound in sucrose, but may also be bought in a pure form. A link between sugar-sweetened drinks (SSD) and body mass index (BMI, kg/m2) is inferred from systematic reviews of both prospective cohort studies (PCSs) and randomized, controlled trials (RCTs) (Malik et al., 2006; Wolf and Dansinger, 2008). The link is seemingly strong because such studies rank highly among types of studies according to evidence-based principles on causality. On the other hand, the study results are heterogeneous, and more objective meta-analysis shows SSDs to have a “small” effect on BMI (Forshee et al., 2008); therefore, a focus on fructose and SSD may then serve only to divert attention from major causes of obesity (Storey, 2008). A number of complications and false claims arise when interpreting epidemiological and interventional studies on fructose or SSDs. The first is a notion that high-fructose corn syrup (HFCS) differs from suc...

Two-Generation Reproduction Study of Erythritol in Rats

Erythritol was fed at dietary concentrations of 0, 2.5, 5, or 10% to Crl:(WI) WU BR rats of both sexes through two successive generations (F0and F1). Twenty-four rats of each sex were mated in each group. For each generation one litter was reared until the pups were 21 days old. In the 10% erythritol group, food consumption among F0-males and -females was initially significantly reduced until the animals adapted to the erythritol diet during the first week of the study. Thereafter, food intake was higher than in controls. A consistently increased food intake also was seen in F1-males and -females of this dose group. This effect was considered to result from the caloric dilution of the food by erythritol, which has a low physiological energy value. The lower body weight and weight gain of the F0-animals of the 10% erythritol group were attributed to the initially reduced food consumption and occurrence of transient diarrhea until the animals had adapted to the erythritol intake. In the F1-animals of the 10% erythritol group, which were adapted to the treatment from weaning, the rate of body weight gain did not differ from controls. The F1-males and -females of this dose group did, however, have a reduced body weight from weaning, which was attributed to a reduced energy intake among the corresponding F0-dams during Weeks 2 and 3 of lactation. This effect was not seen in the F2-generation. It is concluded that under the conditions of this experiment, the intake of erythritol had no adverse effect on fertility and reproductive performance of parent rats or on the development of their progeny. Gross necropsy and microscopic examination of the parenteral reproductive organs also did not reveal treatment-related changes.

A 20-month olestra feeding study in dogs

Three groups of beagle dogs (five/sex/group) were fed olestra, a mixture of octa-, hepta- and hexa-esters of sucrose formed with long-chain fatty acids, at 0, 5 or 10% of the diet for 20 months. The objective of the study was to assess the potential chronic toxicity of olestra in a non-rodent species. The feed was supplemented with vitamins A and E to ensure that the diets were nutritionally adequate and comparable for all groups. The levels of supplementation were established in a 91-day feeding study. Survival was 100% and growth was not affected by olestra. Olestra-fed animals consumed more feed than controls, apparently to compensate for the caloric dilution of the diet by olestra, but the increases were generally not statistically significant. No biologically significant changes were seen in haematological or serum biochemical parameters or in vitamin D and vitamin K status of the animals. Histopathology revealed no olestra-related effects. Isolated incidences of soft stools, apparently resulting from the large amounts of undigested olestra, were noted in olestra-fed animals. The results of this study indicate that olestra was not toxic when fed to dogs at up to 10% of the diet for 20 months.

Plans by Katherine Porikos for long-term studies of the role of caloric dilution in the control of human food intake

Plans by Katherine Porikos for long-term studies of the role of caloric dilution in the control of human food intake

Compensation for caloric dilution in humans given unrestricted access to food in a residential laboratory

Six adult male research volunteers, in two groups of three subjects each, lived continuously in a residential laboratory for 14 days. All contact with the experimenters was through a networked computer system and subjects' behaviors, including food intake, were continuously recorded. During the first part of the day, subjects remained in their private rooms doing work activities. During the remainder of the day, they had the option to socialize with each other. A wide variety of food items were continuously available. Subjects were in complete control of their pattern of food intake and could consume any item, or number of items, at any time during the day. On days 6 through 11, reduced calorie versions of approximately one third of the food items were covertly substituted for the regular caloric content items. This manipulation decreased intake from the reduced-calorie group of foods by 500 kcal. The subjects immediately and completely compensated for the loss of calories by increasing the number of non-calorie-manipulated food items consumed. When regular calorie foods were again available during the last 3 days of the experiment, subjects failed to compensate for this increase in caloric intake. Thus, under conditions of unlimited access to food, human volunteers completely compensated for caloric dilution, but were less accurate in responding to increases in caloric intake.

Polysiloxane: potential noncaloric fat substitute; effects on body composition of obese Zucker rats

Phenylmethylpolysiloxane (PS), a noncaloric, nonabsorbable liquid oil, was studied for effects on body comparison as fat substitute in the diet. Two groups of female obese Zucker rats were fed either a control low-fat (LF) or an experimental diet containing PS (22% wt/wt) incorporated into LF. Two additional groups were fed either PS or cellulose (CE) in diet providing equivalent caloric dilution. Rats on PS lost weight whereas LF control rats gained. Dissectible fat and adipocyte size of PS were smaller than those of LF. Food intake, body water, and adipocyte number did not differ between PS and LF. Body protein on PS increased only in proportion to weight. When both diets were diluted, PS animals lost more weight than CE controls despite similar food intakes, suggesting absorption of calorigenic substances derived from partial digestion of CE but not PS by intestinal microflora. Obese rats did not compensate for caloric dilution with PS.

The effects of caloric dilution on meal patterns and food intake of ponies

In order to determine if horses will increase their intake in response to caloric dilution, four pony geldings were fed ad lib a mixed grain diet either undiluted (3.4 Mcal/kg of digestible energy) or diluted (wt/wt) with 25% sawdust (2.6 Mcal/kg) or with 50% sawdust (1.7 Mcal/kg). The mean daily caloric intake was 17,457 kcal (3.4 Mcal diet), 17,546 kcal (2.6 Mcal diet) and 12,844 kcal (1.7 Mcal). The mean time spent eating was 246 (3.4 Mcal), 351 (2.6 Mcal), and 408 (1.7 Mcal) minutes/day. Meal size increased and meal frequency decreased with increasing dilution. The median long survivorships of intermeal intervals were 6.4 min (3.4 Mcal), 3.95 min (2.6 Mcal) and 4.91 min (1.7 Mcal). Ponies responded to caloric dilution by increasing the volume of intake to maintain caloric intake when the diet had 25% diluent. When the diet was diluted by 50%, intake was increased, but not at a rate adequate to maintain caloric intake. However, the ponies were able to maintain body weight.

Sucrose polyester and covert caloric dilution

Total daily caloric intake was measured in 10 obese subjects when sucrose polyester (SPE), a nonabsorbable synthetic fat, covertly replaced conventional fats in a single crossover study consisting of three periods: a period of 7 to 14 days to determine baseline caloric intake and two 20-day study periods. An average of 60 g SPE/day replaced conventional fat in one of the two study periods. During both study periods, 60% of the base line caloric intake was "required intake" at mealtime; an additional 60% of base line caloric intake was allowed as "free choice" foods at a specified snacktime. It was thus possible during both study periods to consume more than 100% of the base line caloric intake. In the SPE study period, 40 g SPE replaced 40 g conventional fat for every 1200 kcal of required intake, resulting in a 30% reduction in mealtime caloric intake. Mean total caloric intake (meal and snack) fell 23% during the SPE period (p less than 0.05), despite an average daily weight loss of 0.18 kg. Snack caloric intake did not increase significantly to compensate for caloric dilution of the meals during the SPE period. These results indicate that the obese may not detect or may not compensate for covert dilution of fat calories with SPE. In addition, during the SPE period, there was a 10% reduction in total plasma cholesterol, a 14% reduction in low-density lipoprotein cholesterol, and a 10% reduction in triglyceride concentration. Thus, fat replacement with SPE may benefit weight reduction regimens in obese subjects by facilitating decreased caloric intake and by improving the circulating lipoprotein profile as well.

Interaction of Dietary Protein with Cellulose in the Adaptation to Caloric Dilution by Weanling Rats

The adaptive response of food intake to increasing levels of dietary cellulose was studied in weanling rats fed limiting amounts of dietary protein of different qualities. At low levels of dietary cellulose, the food intake depends on protein quality. As the cellulose levels were increased, the diet and gross energy digestibilities diminished, yielding diets with lower digestible energy contents. The rats fed the higher quality protein were able to compensate for this caloric dilution, increasing their food consumption enough to keep constant their digestible energy intake. The animals fed a lower quality protein, however, were unable to make this adaptive increase in food intake. As a result, although gross food intake remained stable, cellulose constituted an increasing proportion of it and the digestible energy consumption of these animals diminished. Water consumption in this trial appears to reflect the animal's digestible energy intake rather than cellulose consumption. The above observations may be considered as an indication that a smooth regulation of the energy intake occurs only with a complete or non-deficient diet and that deficient, abnormal or unusual diets upset this process. In the present experimental situation, when dietary protein is inadequate, the animal can no longer make appropriate compensatory increases in its food consumption to keep its digestible energy intake constant.cellulose dietary protein caloric dilution food intake

Regulation of food intake in monkeys: Response to caloric dilution

Ability to regulate level of energy intake was studied in adult rhesus monkeys ( Macaca mulatta) using calorically diluted diets. Twenty-four hour access to a complete liquid diet was provided via leakproof gravity feeders. The addition of water provided 4 caloric concentrations over the range of 0.5 to 1.35 kcal/ml. Average caloric intake per kg body weight was 84 ± 0.7 kcal/kg (mean ± SE). Seven of the eight monkeys maintained a constant caloric intake by adjusting oral intake in response to randomly ordered but sustained changes in caloric density. One monkey ingested a significantly higher caloric load while receiving the highest density diet. Rates of compensation for dilution following each diet change varied widely, occurring over periods of 3 days to 2 weeks. It was concluded that individual monkeys vary significantly in the rat of adjustment to caloric dilution, and thus long term studies must be used in studying controls of feeding in monkeys.

Dietary fiber and obesity ,

It has been suggested that sufficient fiber in the diet will tend to prevent excessive food intake and depot fat accumulation by decreasing the caloric density of the diet, slowing rate of food ingestion, increasing the effort involved in eating, promoting intestinal satiety, and interfering slightly with efficiency of energy absorption. The increase in the prevalence of obesity in Western countries since 1900 has taken place concurrently with marked changes in the nature of the diet. Per capita intake of dietary fiber associated with starchy foods has greatly decreased, but intake of fiber associated with fruits and green vegetables has increased. Thus, although the type of fiber in the diet has changed, the total quantity may not have diminished considerably. Studies of the effect of caloric dilution with cellulose and other metabolically inert bulking agents have disclosed little or no inhibitory effect on the spontaneous energy intake of nonobese laboratory animals and human subjects. Nevertheless, there is evidence that obese rats and humans may defend their excess weight against nutritive dilution with less tenacity than their nonobese counterparts. The hypothesis that dietary fiber can protect against obesity therefore deserves further testing since an increase in the fiber content of the diet may tend to prevent overeating and excessive weight gain even if it does not reduce spontaneous energy intake in nonobese organisms.

Título en español.

Dos experimentos con gallinas Liornas blancas se efectuaron para evaluar raciones que contenían de 0 a 30% de mosto deshidratado. Este, obtenido de melaza fermentada, se mezcló con un alimento comercial para ponedoras. El tratamiento testigo fue el alimento comercial puro. Las gallinas se alojaron en jaulas individuates. Las raciones se isonitrogenizaron añadiéndoles harina de atún, pero las diferencias en valor calórico y el contenido en otros nutrimentos no se compensaron. En los dos experimentos se usaron bloques distribuidos al azar, con 10 gallinas por tratamiento en el primero y 15 en el segundo. El período de comparación fue de 42 días en el primer experimento y de 50 en el segundo. En la primera prueba, el tratamiento testigo -la ración comercial- superó al tratamiento de 30% de mosto (P < .01) en frecuencia de postura (81.0 contra 58.1 %), (P < .05) peso medio del huevo (62.3 contra 56.5 g) y (P < .01) gramos de alimento por gramo de huevo (2.17 contra 3.68). El testigo también superó al tratamiento de 20% de mosto (P < .01) en frecuencia de postura (68.6%) y (P < .05) en la transformación del alimento en postura (3.10). Las raciones con 5 y 10% de mosto no difirieron significativamente de la testigo. En la segunda prueba, que no incluyó ración sin mosto, las frecuencias de postura (70.6 a 65.1%) en los niveles de 10, 12.5, 15, 17.5 y 20% no difirieron significativamente. El peso medio del huevo fue mayor (P < .05) en las raciones de 15 y 17.5% de mosto (63.0 y 63.2 g) que en la de 20% (59.9 g). La transformación del alimento fue más alta (P < .05) en la ración con 10% de mosto (2.58) que en la que contenía 20% (3.13). La cantidad de alimento por gramo de huevo aumentó .048 g con cada adición de 1% de mosto a la ración, lo cual no justifica la sustitución. Los tratamientos no afectaron el consumo de alimento ni la ganancia de peso vivo. El consumo de raciones con más de 10% de mosto produjo excremento progresivamente más acuoso y negruzco, el cual manchó tanto a las gallinas como a los huevos. La ración con 30% de mosto, y en menor grado la de 20%, se convirtieron en una masa pegajosa al exponerlas al aire por varias horas. Las gallinas toleran bien el mosto deshidratado, y tal vez compensando con grasa la reducción de calorías, se podría utilizar eficientemente a niveles bajo el 20% de la ración.

Sex and hormone dependent alterations in responsiveness to caloric dilution

Potential sex differences in the long-term control of feeding behavior in rats was tested by comparing male and female rats in terms of their responsiveness to a 20 and 40 percent diet dilution challenge. During three-day test periods with both levels of diet dilution, female rats increased their daily food intake (FI) significantly more than did male rats. As a further index of greater precision in the long-term control of feeding behavior by female than by male rats, body weight (BWt) was less affected in female than in male rats during the caloric dilution challenges. In a second experiment, gonadectomy was found to attenuate this sexually dimorphic response to a 40% diet dilution test, whereas daily injections of gonadal hormones reestablished the sex difference in FI and BWt changes produced by the dilution challenge. Since responsiveness to the dilution challenge of female rats, but not males, was altered by gonadectomy and steroid treatment, it appears that estrogen shifts the control of feeding behavior in female rats towards more long-term factors.

Effect of covert nutritive dilution on the spontaneous food intake of obese individuals: a pilot study

The present study investigated the feasibility of a new experimental approach for studying the effect of covert nutritive dilution on the spontaneous food intake of obese individuals. Eight obese subjects were studied as inpatients on a metabolic unit for 15 days during which time they were unaware that their food intake was being monitored. A platter method of food presentation encouraged ad libitum ingestion. Caloric dilution was achieved by replacing sucrose-containing products with aspartame-sweetened analogues in an otherwise normal diet. During the base-line period the subjects spontaneously ate sufficient conventional food to maintain or even slightly increase body weight. Covert substitution of aspartame-sweetened products for their sucrose counterparts resulted in an immediate reduction in spontaneous energy intake of approximately 25%. The aspartame analogues were as well accepted as their conventional counterparts, as indicated by the equal quantity of each consumed. These preliminary results demonstrate that, in a metabolic ward setting, it is possible to maintain the spontaneous food intake of obese individuals at levels sufficient to preserve body weight and arbitrarily to decrease those levels of intake by 25% or more through covert changes in the caloric density of the diet.

Intragastric cannulation procedures and rats' food intake and body weight maintenance

Effects upon food and water intakes and body weight maintenance of two procedures for preparing rats with chronic intragastric cannulae were examined. A transient aphagia and rapid weight loss followed installation of the classic nasopharyngeal cannula. Growth was resumed after about a week, but subsequent food and water intakes were chronically depressed in comparison to sham operated animals of the same age. Body weight was also chronically subnormal. The response of these animals to caloric dilution of the diet was, however, normal. In contrast to the nasopharyngeal procedure, a method involving direct cannulation of the stomach wall did not lead to either behavioral or weight regulatory deficits and is therefore recommended.

Caloric compensation in hypothalamic obese rats

The present study explored the influence of pelleted diets on adjustment to caloric dilution in hypothalamic obese rats. Medial hypothalamic lesioned and normal rats were maintained on a high fat diet until the static stage of hyperphagia was reached. They were given three pelleted diets which consisted of undiluted Noyes pellets and Noyes pellets diluted 25 or 50 percent with kaolin. In contrast to previous reports that hypothalamic obese rats do not compensate for caloric dilution of their diet, the obese animals showed as large an increase in food intake on the dilute pelleted diets as did the control animals. These results were interpreted by viewing texture as a dimension of palatability which influences food intake in hypothalamic obese rats.

Caloric compensation in rats with continuous or intermittent access to food

Unpalatability, caloric dilution and brief access all initially depress daily caloric intake. Increasing appetite, decreasing capacity of the food to initiate and to maintain satiety, adaptation of food processing mechanisms, and conditioned increases in meal size subsequently raise intake towards a level which matches caloric input to caloric expenditure (and does not necessarily restore growth to its original trajectory). Food-deprived rats compensate even when access to food is brief, just as freely fed rats do, so long as the adverse factors do not force caloric intake persistently so low that deleterious adaptations and a reinforcement of dietary aversion conditioning begin to operate. Also, when intake is measured over the same short period of time, freely fed rats can be observed to respond to taste at least as strongly as starved rats. Eating for calories is not a set of reactions to some obscure stimulus, on a level with eating for taste, but is the organism's energy balance approaching null point by complex interactions between behavioral control and nutrient processing.