SEARCH · PubMed Health

Results for “Caloric Restriction”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources

PubMed1999

Increased NPY activity in the PVN contributes to food-restriction induced reductions in blood pressure in aortic coarctation hypertensive rats.

We hypothesized that hypothalamic NPYergic mechanisms mediate the blood pressure lowering effect of caloric restriction in hypertensive rats. Aortic coarctation-induced (AC) hypertensive rats (n=25) were assigned to either an ad libitum fed control group (AL) or food restricted group (FR; 60% of AL consumption) for 3 weeks. Rats were instrumented chronically with vascular catheters and bilateral guide cannulae directed at the paraventricular hypothalamic nuclei (PVN). Blood pressure (BP) and heart rate (HR) responses to bilateral PVN microinjection of saline (200 nl) or the putative NPY receptor antagonists [D-Trp32]NPY(1-36) (3.3 micrograms/200 nl) and [D-Tyr27,36 Thr32]NPY(27-36) (D-NPY(27-36); 3.3 micrograms/200 nl) were determined. The FR rats were then refed and cardiovascular responses to PVN injections of NPY receptor antagonists were again determined. FR rats had significantly reduced resting BP (159+/-4 vs. 129+/-4 mmHg) and HR (360+/-11 vs. 326+/-9 bpm) compared to AL controls. Refeeding restored BP and HR of FR rats to levels similar to AL (BP=153+/-4 mmHg, HR=359+/-11 bpm). PVN administration of [D-Trp32]NPY produced foraging behavior and concurrent increases in BP and HR in FR, AL and Re-fed rats. The behavioral activation suggests that [D-Trp32]NPY(1-36) produced activation of NPY receptors. In contrast, D-NPY (27-36) did not produce any behavioral response or affect BP or HR in AL or Re-fed rats. In FR rats, D-NPY (27-36) produced significant increases in BP (peak=15+/-3 mmHg) which partially reversed the effect of FR on BP. Thus, in FR rats with reduced BP, PVN administration of an NPY receptor antagonist increases BP. NPY blockade in the PVN accounted for about 50% of the BP effect of food restriction, thus other mechanisms are likely to be involved. These findings are consistent with the hypothesis that NPYergic mechanisms may contribute to the reduction of BP produced by food restriction.

Animals↗

PubMed2001

The effects of food restriction in man on hepatic metabolism of acetaminophen.

BACKGROUND: Recent reports have suggested that food deprivation may contribute to acetaminophen hepatotoxicity by shunting drug detoxification from the conjugative to the potentially toxic oxidative pathways. METHODS: This study assessed this concept in a prospective study of food restriction of 500 calories/day over 5 days and also of 1000 calories/day over 13 days. Obese, otherwise normal, individuals received 2 g acetaminophen orally at the start and again after food restriction. Sequential liver tests, as well as serum and urine acetaminophen and its derivatives were measured. RESULTS: In both food-restricted groups there was no evidence of any change in the elimination or in the metabolic pattern of acetaminophen removal. Liver tests remained normal. The average weight loss was about 6 pounds. CONCLUSIONS: Our data, with this brief, but major degree of food restriction, and this load of acetaminophen (half-maximal daily dose), do not demonstrate an effect of caloric restriction on acetaminophen disposition.

Acetaminophen↗

PubMed1985

Influence of selected amino acid deficiencies on somatomedin, growth and glycosaminoglycan metabolism in weanling rats.

The effects of lysine-, methionine- or histidine-deficient diets compared to a control diet fed ad libitum or 15, 10 or 5 g/d were studied in weanling rats. Feed intake was 5-7 g/d for the amino acid-deficient animals. After 3 wk, all amino acid-deficient rats had lost more weight (P less than 0.01) than the controls fed at comparable energy levels. Serum somatomedin (Sm) activity was significantly decreased in lysine- (0.55 U/ml), methionine- (0.32 U/ml) and histidine-deficient (0.38 U/ml) rats compared to rats fed the control diet ad libitum (1.6 U/ml). Differences between amino acid-deficient and calorie-restricted animals were not significant. A similar response was observed in 35SO4 uptake by cartilage glycosaminoglycans (GAG). Caloric restriction and amino acid deficiency each resulted in lower 35SO4 uptake by cartilage GAG than occurred with ad libitum feeding, but there were no significant differences between the rats fed amino acid-deficient diets and those fed 5 or 10 g of the control diet. Compared to rats fed the control diet ad libitum, plasma growth hormone (GH) concentrations were lower in the rats fed 5 or 10 g of control diet per day and in those fed amino acid-deficient diets (P less than 0.05), but GH concentrations were not consistent with the growth retardation observed. The results confirm that Sm and GAG activities are reduced in protein-energy restriction independent of GH. However, changes could not be attributed to specific deficiencies of lysine, methionine and/or histidine.

Amino Acids, Essential↗

PubMed2005

Competing dietary claims for weight loss: finding the forest through truculent trees.

In response to an accelerating obesity pandemic, competing weight-loss diets have propagated; those touting carbohydrate restriction are currently most in vogue. Evidence that sustainable weight loss is enhanced by means other than caloric restriction, however, is lacking. Whereas short-term weight loss is consistently achieved by any dietary approach to the restriction of choice and thereby calories, lasting weight control is not. Competing dietary claims imply that fundamental knowledge of dietary pattern and human health is lacking; an extensive literature belies this notion. The same dietary and lifestyle pattern conducive to health promotion is consistently associated with weight control. A bird's eye view of the literature on diet and weight reveals a forest otherwise difficult to discern through the trees. Competing diet claims are diverting attention and resources from what is actually and urgently needed: a dedicated and concerted effort to make the basic dietary pattern known to support both health and weight control more accessible to all.

Body Composition↗

PubMed2005

Advanced glycation in health and disease: role of the modern environment.

It is believed that intracellular and extracellular advanced glycation (AGEs) or lipoxidation end products (ALEs), together with dysregulated glucose and lipid metabolism, are important contributors to oxidant or carbonyl stress, enhanced cellular redox-sensitive transcription factor activity, and impaired innate immune defense, causing over time inappropriate inflammatory responses. However, neither the magnitude nor the persistent nature of this increased prooxidant state are completely understood. A significant correlation has been found between ingested and circulating AGEs in humans in recent years. Based on animal studies, the injurious impact of diet-derived AGEs to vascular and kidney tissues is estimated to rival or even exceed that caused by hyperglycemia or hyperlipidemia. Consistent with this view, dietary AGE restriction has been associated with suppression of several immune defects, insulin resistance, and diabetic complications, whether genetically or diet induced, despite persistent diabetes. These findings are in support of clinical evidence from subjects with diabetes or vascular or kidney disease. Most recently, evidence from animal studies points to AGE restriction as an effective means for extending median life span, similar to that previously shown by marked caloric restriction. We conclude that excessive AGE consumption, in the current dietary/social structure, represents an independent factor for inappropriate oxidant stress responses, which may promote the premature expression of complex diseases associated with adult life, such as diabetes and cardiovascular disease.

Diet↗

PubMed1994

[Hypertension in pregnancy--dietary aspects].

Dietary recommendations about prophylaxis and treatment of hypertension in pregnancy are manifold and controversial. Only a few studies of evidence are published till now. Recommendations may be derivable from physiology and pathophysiology of hypertension in pregnancy. A normal protein intake of 70-80 g is to be recommendable, neither protein restriction nor increased protein supply. Protein restriction may be sensible only for blocking a progression of a chronic renal insufficiency. The value of caloric restriction is not secured, but an increasing body fat is not recommendable. Neither restriction nor increased supply of sodium can generally be recommended. The same is valit with respect to liquid supply, which is to be restricted in cases with hyponatriemy and hypoosmolality. Substitution of potassium and magnesium is not necessary, of linoleic acid and water-soluble vitamins not sufficiently verified. The efficacy of calcium substitution on hypertension in pregnancy has to evaluated by further studies.

Feeding Behavior↗

PubMedDate not supplied

Effects of aging and dietary restriction on DNA polymerases: gene expression, enzyme fidelity, and DNA excision repair.

Hepatic DNA polymerases isolated from young and old C57BL/6N mice fed ad libitum or calorically restricted differed in chromatographic characteristics, binding affinity for DNA template-primer, specific activity, and fidelity of synthesis. DNA polymerase alpha total and specific activity declined slightly, while the nucleotide misincorporation frequency increased dramatically, with increased age of the donor animals. A positive correlation was observed between polymerase alpha specific activity and the affinity of enzyme binding to activated DNA template-primer. Both the age-associated decline in enzyme activity and the decrease in fidelity of synthesis were modified by dietary restriction, with higher specific activity levels and lower misincorporation frequencies for DNA polymerases from dietarily restricted animals compared with ad libitum animals of all ages. Fidelity of both DNA polymerase alpha and beta increased following treatment with the phosphoinositide hydrolysis product inositol-1,4-bisphosphate. The data suggest that dietary restriction could play an important role in decreasing the age-associated decline in function of physiological systems sensitive to decreased or defective DNA synthesis.

Aging↗

PubMedDate not supplied

Calorie restriction increases light-dependent photoreceptor cell loss in the neural retina of fischer 344 rats.

We investigated the effect of > or = 8 months of 40% caloric restriction (CR) on photoreceptor cell loss in 12, 18, and 24 month-old Fischer 344 rats (N = 154). Rats were reared at the NIA Biomarkers Program, National Center for Toxicological Research. Photoreceptor cell density, assessed histologically, declined with age in both the CR-fed and ad lib (AL)-fed cohorts (P < 0.000), but declines were more pronounced in the CR cohort (P < 0.0005). The deleterious effect of CR was most pronounced in the central as opposed to the peripheral retina (P = 0.008), suggesting a light-dependent mechanism. Photoreceptor cell density was inversely associated with rearing under bright light (300-750 lux) as compared with rearing under lower illuminance (< or = 200 lux) (P < 0.0005). However, the deleterious effect of bright light on photoreceptor cell density was more pronounced in the CR cohort (P = 0.04). Effects of CR on circadian activity are likely to increase the actual light exposure of the CR cohort and may explain the apparent inability of CR to delay retinal aging in albino rats.

Aging↗

PubMed1992

The rate of DNA damage and aging.

A new theory of aging based on the rate of DNA damage is presented, and the relationship between the rate of oxidative DNA damage and maximum life span (MLS) of mammalian species is explored. In humans the level of oxidative DNA damage, as measured by urinary biomarkers, can be modulated by caloric restriction and dietary composition. Consequently, longevity may depend not only on the basal metabolic rate but also on dietary caloric intake and the type of diet. The theory may provide the basis for a practical approach for reduction of degenerative diseases in general, extension of life expectancy, and optimization of individual lifestyles.

Aging↗

PubMed1996

Intergeniculate leaflet lesion and daily rhythms in food-restricted rats fed during daytime.

In control rats kept under light/dark cycle (LD) and fed during daytime 50% of ad lib food intake, the acrophase of temperature rhythm was 5 h phase-advanced, and plateaued close to the light/dark transition. The nocturnal pattern of locomotor activity rhythm was 6 h phase-advanced. By contrast, in food-restricted rats with electrolytic lesion of intergeniculate leaflet (IGL: IGLX group), there was only a 1 h phase-advance of the acrophase of temperature rhythm. Furthermore, except for a feeding-associated activity, the nocturnal pattern of activity of food-restricted IGLX rats remained unchanged. This demonstrates the involvement of IGL in the phase-advancing properties of a timed caloric restriction in LD.

Animals↗

PubMed2003

Effect of a high-protein, energy-restricted diet on weight loss and energy expenditure after weight stabilization in hyperinsulinemic subjects.

OBJECTIVE: To determine the effect of replacing some dietary carbohydrate with protein, during energy restriction, on weight loss, total energy expenditure (TEE), resting energy expenditure (REE), respiratory quotient (RQ), and the thermic effect of feeding (TEF) in subjects with hyperinsulinemia. DESIGN: Parallel, clinical intervention study of 12 weeks energy restriction (6.5 MJ/day) and 4 weeks energy balance (8.2 MJ/day) in two groups of subjects randomly assigned to either a high-protein (HP) diet (27% of energy (%E) as protein, 45%E as carbohydrate) or a lower-protein (LP) diet (16%E as protein, 57%E as carbohydrate). SUBJECTS: A total of 36 obese nondiabetic volunteers with hyperinsulinemia (10 males/26 females, aged 34-65 y, BMI 28-43 kg/m(2), fasting insulin 12-45 mU/l). MEASUREMENTS: Body weight and composition, TEE, REE, and RQ were measured at baseline and at week 16. In addition, the TEF to an HP or LP meal was determined for 3 h, at baseline and at week 16. RESULTS: After 16 weeks, weight loss was similar in response to each diet; the overall decrease was 7.9+/-0.6 kg (P<0.001), of which 6.8+/-0.5 kg was fat (P<0.001). REE fell similarly with each diet; the overall decrease was 719+/-106 kJ/day (P<0.001). The TEF was 2% greater after the HP than after the LP meal at baseline (P<0.01) and 0.8% greater at week 16 (P=0.35). After 16 weeks, the TEF was not reduced in either dietary group. There was no change in TEE after 16 weeks. CONCLUSION: In subjects with hyperinsulinemia an energy-restrictive diet containing an increased protein-to-carbohydrate ratio does not enhance weight loss or significantly affect energy expenditure. Caloric restriction, rather than the macronutrient composition of the diet, is the most important determinant of weight loss.

Body Composition↗

PubMed1982

Serum bile acids in Gilbert's syndrome before and after reduced caloric intake.

Fasting and postprandial serum bile acids were determined before and after reduced caloric intake in patients with Gilbert's syndrome. Cholic and chenodeoxycholic acid were determined by radioimmunoassay. In all patients there was a pronounced increase in serum bilirubin (mean increase, 140%) after caloric restriction. However, both fasting and postprandial levels of serum bile acids were within the normal range before and after reduced caloric intake. The results indicate that different mechanisms are involved in the hepatic uptake and secretion of bile acids and bilirubin. Moreover, the results show that determinations of serum bile acids can be used to assess liver function in patients with Gilbert's syndrome irrespective of the degree of hyperbilirubinemia.

Adolescent↗

PubMed1991

Effects of aging and dietary restriction on DNA polymerase expression in mice.

DNA polymerase alpha was isolated from livers of 6-month-, 16-month-, or 26-month-old mice fed ad libitum, or calorically restricted. The enzymes differed in chromatographic characteristics, binding affinity for DNA, and activity, with both total activity and specific activity of DNA polymerase alpha decreasing as a function of age. A positive correlation was observed between polymerase alpha specific activity and the affinity of enzyme binding to activated DNA template-primer. The age-associated decline in enzyme activity was modified by dietary restriction, with measurably higher activity seen for polymerases from dietary restricted animals compared with ad libitum animals of all ages. The data suggest that dietary restriction could act to delay the age-associated decrease in cellular capacity for DNA synthesis, which may play a significant role in prolonging the onset of age-related diseases in which decreased DNA synthesis is a potential component.

Aging↗

PubMed2004

Body mass reduction markedly improves muscle performance and body composition in obese females aged 61-75 years: comparison between the effects exerted by energy-restricted diet plus moderate aerobic-strength training alone or associated with rGH or nandrolone undecanoate.

OBJECTIVE: To investigate the effectiveness of a body mass reduction programme entailing diet caloric restriction and moderate physical activity with or without supplementary treatment with recombinant (r) GH or steroids to improve body composition and muscle performance in severely obese women aged 61-75 years. METHODS: Twenty women were randomly assigned to one of three groups: body mass reduction alone; body mass reduction plus rGH; body mass reduction plus nandrolone undecanoate. Body composition, isotonic muscle strength and anaerobic power output during jumping were determined before and after the 3-week period. RESULTS: Whatever the experimental group considered, body mass (P<0.01), body mass index (P<0.05) and fat mass (P<0.05) decreased significantly, whereas muscle strength and power increased significantly (P<0.05) after the intervention. CONCLUSION: Small body mass reductions after 3 weeks of energy-restricted diet combined with moderate aerobic and strength exercise are associated with significant improvements in upper and lower limb muscle strength and power and reduction of fat mass in severely obese women aged 61-75 years. Although the association of rGH or nandrolone undecanoate does not appear to exert additional effects on body composition and muscle performance attained by body mass reduction alone, further additional studies with larger study groups, different dosages and more prolonged periods are required for definitive conclusions to be drawn.

Aged↗

PubMed2000

Testicular regression in response to food restriction and short photoperiod in white-footed mice (Peromyscus leucopus) is mediated by apoptosis.

Short day lengths or reduced food availability are salient cues for small mammals that breed seasonally. Photoperiod-mediated gonadal regression in white-footed mice (Peromyscus leucopus) is a slow, orderly process that involves testicular apoptosis. Testicular regression in response to restricted caloric intake is relatively rapid, and it is generally reversed quickly by ad libitum (ad lib) feeding. To determine the contribution of apoptotic cell death during food restriction, and to examine possible interactions with photoperiod, mice housed in long (16L:8D) or short (8L:16D) photoperiods were fed either ad lib or 70% of their average ad lib intake. Testes were removed at 2, 4, 6, or 8 wk of experimental treatment. Apoptotic activity was determined by in situ TUNEL labeling and assessment of DNA laddering. Significant (P < 0.05) gonadal regression in response to short days was first detected at 8 weeks in mice fed ad lib. Food-restricted, long-day mice also showed significant testicular regression at 8 wk. Combined exposure to short day lengths and food restriction resulted in significant testicular regression at 6 wk (P < 0.05). TUNEL labeling was slightly, though significantly, elevated in germ cells at 2 and 4 wk in long-day food-restricted mice (P < 0.05). TUNEL labeling was also elevated in short-day food-restricted males at these early times but then increased nearly 5-fold at 6 and 8 wk in these mice (P < 0.001). DNA laddering confirmed elevated apoptosis. Overall apoptotic activity negatively correlated with paired testis mass, plasma testosterone, and spermatogenic index measurements in both ad lib and food-restricted males. Few histological markers of necrotic cell death were observed in any group. Taken together, these results suggest that testicular regression in response to limited caloric intake or short days is mediated by apoptosis.

Animals↗

PubMed2000

The obesity epidemic: metabolic imprinting on genetically susceptible neural circuits.

The apparent obesity epidemic in the industrialized world is not explained completely by increased food intake or decreased energy expenditure. Once obesity develops in genetically predisposed individuals, their obese body weight is avidly defended against chronic caloric restriction. In animals genetically predisposed toward obesity, there are multiple abnormalities of neural function that prime them to become obese when dietary caloric density and quantity are raised. Once obesity is fully developed, these abnormalities largely disappear. This suggests that obesity might be the normal state for such individuals. Formation of new neural circuits involved in energy homeostasis might underlie the near permanence of the obese body weight. Such neural plasticity can occur during both nervous system development and in adult life. Maternal diabetes, obesity, and undernutrition have all been associated with obesity in the offspring of such mothers, especially in genetically predisposed individuals. Altered brain neural circuitry and function often accompanies such obesity. This enhanced obesity may then be passed on to subsequent generations in a feed-forward, upward spiral of increasing body weight across generations. Such findings suggest a form of "metabolic imprinting" upon genetically predisposed neural circuits involved in energy homeostasis. Centrally acting drugs used for obesity treatment lower the defended body weight and alter the function of neural pathways involved in energy homeostasis. But they generally have no permanent effect on body weight or neural function. Thus, early identification of obesity-prone mothers, infants, and adults and treatment of early obesity may be the only way to prevent the formation of permanent neural connections that promote and perpetuate obesity in genetically predisposed individuals.

Animals↗

PubMed2003

Pandemic obesity and the contagion of nutritional nonsense.

The United States is the epicenter of an obesity pandemic. As more countries acculturate to a Western lifestyle, rates of obesity and its sequelae are rising steadily in both adults and children. In response, a variety of weight-loss diets emphasizing alternative distributions of macronutrient classes have been promoted with considerable success. Among the most popular is the so-called "Atkins Diet," in which carbohydrate restriction is touted as the key to weight loss. Despite claims, however, evidence that weight loss is enhanced by means other than caloric restriction is lacking. Also lacking is evidence that fad diets produce sustainable weight loss. Most important, fad diets generally ignore or refute what is known about fundamental associations between dietary pattern and human health. Cancer, cholera, and AIDS induce rapid weight loss, highlighting the potential incompatibility of weight loss by any means with health. Available data suggest that long-term weight loss is most consistently achieved by adherence to a fat-restricted diet abundant in grains, vegetables, and fruit, along with regular physical activity, a lifestyle notably conducive to the promotion of overall health. Fad diets, potential harms of which are well characterized, should be presumed "guilty" of incompatibility with human health until or unless proved otherwise; the burden of proof should reside with proponents. In the interim, the clinical and public health communities should work to empower individuals with knowledge needed to reconcile weight control with health promotion; support policies that mitigate obesogenic environmental conditions; and offer unified resistance to the contagion of dietary propaganda.

Bias↗

PubMed2001

Adult height and risk of breast cancer: a possible effect of early nutrition.

The relationship of breast cancer to early reproductive development and height suggests that fetal and childhood nutrition may be important in its aetiology. Caloric restriction sufficient to reduce adult height may reduce breast cancer risk. During World War II (WWII) there was a marked reduction in average caloric intake in Norway that resulted in greater nutritional diversity. We hypothesized that a positive association between height and risk of breast cancer would be stronger among women who were born during this period than among women born before or after the war. A total of 25 204 Norwegian women were followed up for approximately 11 years, and 215 incident cases of breast cancer were registered. We found the strongest positive association between height and breast cancer among women born during WWII: women in the tallest tertile (>167 cm) had a relative risk of 2.5 (95% confidence interval = 1.2-5.5) compared with the shortest (< or = 162 cm). Among women born before or after the war we found no clear association with height. The association with height in the WWII cohort may imply a role for early nutrition in breast cancer aetiology.

Adult↗