Role of dietary calcium and dairy products in modulating adiposity

Dietary calcium plays a pivotal role in the regulation of energy metabolism. High-calcium diets attenuate adipocyte lipid accretion and weight gain during overconsumption of an energy-dense diet and increase lipolysis and preserve thermogenesis during caloric restriction, thereby markedly accelerating weight loss. Our studies of the agouti gene demonstrate a key role for intracellular Ca²⁺ in regulating adipocyte lipid metabolism and TG storage. Increased intracellular Ca²⁺ resulting in stimulation of lipogenic gene expression, and lipogenesis and suppression of lipolysis resulting in adipocyte lipid filling and increased adiposity. Moreover, we recently demonstrated that the increased calcitriol produced in response to lowcalcium diets stimulates adipocyte Ca²⁺ influx and, consequently, promotes adiposity. Accordingly, suppressing calcitriol levels by increasing dietary calcium is an attractive target for obesity intervention. In support of this concept, transgenic mice expressing the agouti gene specifically in adipocytes (a human-like pattern) respond to low-calcium diets with accelerated weight gain and fat accretion, whereas high-calcium diets markedly inhibit lipogenesis, accelerate lipolysis, increase thermogenesis, and suppress fat accretion and weight gain in animals maintained at identical caloric intakes. Further, low-calcium diets impede body fat loss, whereas high-calcium diets markedly accelerate fat loss in transgenic mice subjected to caloric restriction. Dairy sources of calcium exert markedly greater effects in attenuating weight and fat gain and accelerating fat loss. This augmented effect of dairy products is likely due to additional bioactive compounds in dairy that act synergistically with calcium to attenuate adiposity. These concepts are confirmed by both epidemiological and clinical data, which demonstrate that increasing dietary calcium results in significant reductions in adipose tissue mass in obese humans in the absence of caloric restriction and markedly accelerates the weight and body fat loss secondary to caloric restriction, whereas dairy products exert significantly greater effects. These data indicate an important role for dairy products in both the prevention and treatment of obesity.     

Dietary Linoleic Acid Elevates the Endocannabinoids 2-AG and Anandamide and Promotes Weight Gain in Mice Fed a Low Fat Diet

Dietary intake of linoleic acid (LNA, 18:2n-6) has increased dramatically during the 20th century and is associated with greater prevalence of obesity. The endocannabinoid system is involved in regulation of energy balance and a sustained hyperactivity of the endocannabinoid system may contribute to obesity. Arachidonic acid (ARA, 20:4n-6) is the precursor for 2-AG and anandamide (AEA), and we sought to determine if low fat diets (LFD) could be made obesogenic by increasing the endocannabinoid precursor pool of ARA, causing excessive endocannabinoid signaling leading to weight gain and a metabolic profile associated with obesity. Mice (C57BL/6j, 6 weeks of age) were fed 1 en% LNA and 8 en% LNA in low fat (12.5 en%) and medium fat diets (MFD, 35 en%) for 16 weeks. We found that increasing dietary LNA from 1 to 8 en% in LFD and MFD significantly increased ARA in phospholipids (ARA–PL), elevated 2-AG and AEA in liver, elevated plasma leptin, and resulted in larger adipocytes and more macrophage infiltration in adipose tissue. In LFD, dietary LNA of 8 en% increased feed efficiency and caused greater weight gain than in an isocaloric reduction to 1 en% LNA. Increasing dietary LNA from 1 to 8 en% elevates liver endocannabinoid levels and increases the risk of developing obesity. Thus a high dietary content of LNA (8 en%) increases the adipogenic properties of a low fat diet.     

Short Term High Fat Diet Induces Obesity-Enhancing Changes in Mouse Gut Microbiota That are Partially Reversed by Cessation of the High Fat Diet

The gut microbiota is proposed as a “metabolic organ” involved in energy utilization and is associated with obesity. Dietary intervention is one of the approaches for obesity management. Changes in dietary components have significant impacts on host metabolism and gut microbiota. In the present study, we examined the influence of dietary fat intervention on the modification of gut mucosa-associated microbiota profile along with body weight and metabolic parameter changes. Male C57BL/6J mice (6-week old) were fed a low fat diet (10% kcal fat) as a control or a high fat diet (HFD 60% kcal fat) for 7 weeks. In another group, mice were fed HFD for 5 weeks followed by low fat control diet for 2 weeks (HFD + Control). At 7 weeks, body weight gain, blood glucose and hepatic triacylglycerol levels of mice fed a HFD were significantly higher than that of the control group and the HFD + Control group. There were significant differences in the diversity and predicted functional properties of microbiota in the cecum and colon mucosa between the control group and the HFD group. HFD feeding reduced the ratio of Bacteroidetes to Firmicutes, a microbiota pattern often associated with obesity. The HFD + Control diet partially restored the diversity and composition of microbiota in the cecum to the pattern observed in mice fed a control diet. These results suggest that short-term high fat diet withdrawal can restore metabolic changes and prevent excess body weight gain, however, long-term dietary intervention may be required to optimize the restoration of gut microbiota in mouse.     

High intake,but not low intake,of CLA impairs weight gain in growing mice

CLA has a range of biological properties, including effects on lipid metabolism and body composition in experimental animals. The prevalent isomer of CLA found in the human diet is 9c, 11t-CLA, and it is predominantly found in products containing fat from ruminant animals. This study investigated the effect of dietary CLA on energy balance in mice. Synthetic CLA reduced body fat in growing male BAI B/c mice in a dose-dependent manner over the range 0.25–1.0% w/w CLA in the diet. Weight gain was also reduced at the highest levels of dietary CLA, being only 5.88±2.68 g/4 mice (mean±1 SD) after 4 wk of 2.0% CLA in the diet, compared with weight groups. There was no significant effect on weight gain if diets contained 0.5% synthetic CLA or less. These results suggest that high levels of a synthetic mixture of CLA isomers modify energy metabolism and body composition and that high levels of synthetic CLA impair weight gain and reduce body fat pad mass in growing mice.     

Changes in Endogenous Oxytocin Levels and the Effects of Exogenous Oxytocin Administration on Body Weight Changes and Food Intake in Polycystic Ovary Syndrome Model Rats

Polycystic ovary syndrome (PCOS) is frequently seen in females of reproductive age and is associated with metabolic disorders that are exacerbated by obesity. Although body weight reduction programs via diet and lifestyle changes are recommended for modifying reproductive and metabolic phenotypes, the drop-out rate is high. Thus, an efficacious, safe, and continuable treatment method is needed. Recent studies have shown that oxytocin (OT) reduces body weight gain and food intake, and promotes lipolysis in some mammals, including humans (especially obese individuals), without any adverse effects. In the present study, we evaluated the changes in endogenous OT levels, and the effects of acute and chronic OT administration on body weight changes, food intake, and fat mass using novel dihydrotestosterone-induced PCOS model rats. We found that the serum OT level was lower in PCOS model rats than in control rats, whereas the hypothalamic OT mRNA expression level did not differ between them. Acute intraperitoneal administration of OT during the dark phase reduced the body weight gain and food intake in PCOS model rats, but these effects were not observed in control rats. In contrast, chronic administration of OT decreased the food intake in both the PCOS model rats and control rats. These findings indicate that OT may be a candidate medicine that is efficacious, safe, and continuable for treating obese PCOS patients.     

Body composition, dietary composition, and components of metabolic syndrome in overweight and obese adults after a 12-week trial on dietary treatments focused on portion control, energy density, or glycemic index

ABSTRACT: BACKGROUND: Given the rise in obesity and associated chronic diseases, it is critical to determine optimal approaches to weight management that will also provide improvements in dietary quality and chronic disease risk factors. To our knowledge, no study has examined all these variables in subjects participating in recommended multi-disciplinary weight loss programs using different dietary strategies. Methods: This study compared effects of three dietary approaches to weight loss on body composition, dietary quality and risk factors for metabolic syndrome. In a 12-week trial, sedentary but otherwise healthy overweight and obese adults (19 M & 138 F; 38.7 +/- 6.7 y; BMI 31.8 +/- 2.2) who were attending weekly group sessions for weight loss followed either portion control, low energy density, or low glycemic index diet plans. At baseline and 12 weeks, measures included anthropometrics, body composition, 3-day food diaries, blood pressure, total lipid profile, HOMA, C-reactive protein, and fasting blood glucose and insulin. Data were analyzed by repeated measures analysis of variance. Results: All groups significantly reduced body weight and showed significant improvements in body composition (p<0.001), and components of metabolic syndrome (p<0.027 to 0.002), although HDL decreased (p<0.001). Dietary energy, %fat and %saturated fat decreased while protein intake increased significantly (p<0.001). There were no significant differences among the three groups in any variable related to body composition, dietary quality, or metabolic syndrome components. Conclusion: Different dietary approaches based on portion control, low energy density, or low glycemic index produced similar, significant improvements in body composition, dietary quality, and metabolic syndrome components in overweight and obese adults undergoing weekly weight loss meetings. This may allow for flexibility in options for dietary counseling based on patient preference.     

No evidence of differential effects of SFA,MUFA or PUFA on post-ingestive satiety and energy intake: a randomised trial of fatty acid saturation

Background  

High fat diets have long been associated with weight gain and obesity, and the weak satiety response elicited in response to dietary lipids is likely to play a role. Suppression of appetite and food intake has consistently been shown to be diminished with high fat relative to either high protein or carbohydrate meals. There is however some evidence that the satiating capacity of lipids may be modulated when physicochemical properties are altered, but studies investigating the effect of lipid saturation on appetite have generated inconsistent findings. This study investigated the effects of changes in fatty acid saturation on post-ingestive satiety and energy intake.     

Prenatal diet, nutrient intake and pregnancy outcome in urban Ecuadorian primiparas.

A nutritional survey was conducted in an urban public maternity hospital, Hospital Gineco-Obstétrico Isidro Ayora (HGOIA), located in Quito, Ecuador. Seventy-four primiparas in the third trimester of pregnancy were recruited to assess the influence of sociedemographic factors on food patterns and nutrient intake, and the interrelationship between prenatal nutrient intake, maternal weight gain and pregnancy outcome. Results of the regression analysis indicated that maternal education was the factor most strongly associated with nutrient intake, followed by monthly per capita income. Maternal nutrient intake was next analyzed and compared with the WHO (1974, 1985) and NRC (1980) recommended daily allowances. Results also indicated the average daily intake of energy, protein, phosphorus, vitamins C and A, thiamine, riboflavin, and niacin met or exceeded the recommended daily allowances. Dietary calcium and iron intake, however, were below recommendations. Sodium and fat intake were both relatively high. Higher dietary fat intake was associated with increased birth weight, while lower protein intake was associated with increased risk of delivering a low-birth weight baby. Maternal weight gain during the third trimester predicted baby birth weight and height but not head circumference.     

Fats in human nutrition

Summary Dietary fats represent the most compact chemical energy available to man. They contain twice the caloric value of an equivalent weight of sugar. However dietary fats should not be thought of solely as providers of unwanted calories as fats are as vital to cell structure and biological function as protein. If an individual consumes food items of high fat content, an adequate protein and vitamin intake should be assured in order to provide the lipotropic factors necessary for normal fat metabolism. It may be more judicious to control the total caloric intake under such circumstances rather than to resort to periods of semi-starvation or to drastically decrease the dietary fat intake which could result in an increase in hunger pangs and an actual increase in total caloric intake. If the excess calories furnished by carbohydrates are converted to fatin vivo, the problem of obesity could not be solved under conditions of increased total caloric intake. The problem could be solved by a curtailed intake of a diet which includes meat, milk, eggs, vegetables, fruits, and sufficient cereals and bread to provide for an adequate protein, vitamin, and caloric intake. Dietary fats provide the essential linoleic acid which seems to have both a structural and functional role in animal tissue. Although the optimum total intake of linoleic acid by man has not been established, it is evident that the level of intake in the American dietary pattern could be increased. However the indiscriminate substitution of soft for hard fats seems undesirable as an excess consumption of highly unsaturated fatty acids may change the functional value of the triglycerides in the depot fats and may put an undue stress on the antioxidant supply availablein vivo.     

Different Ratios of Corn and Coconut Oil Blends in High-Fat Diets Influence Fat Deposition without Altering Metabolic Biomarkers in Male Rats

The effects of high-fat diets with the recommended dietary linoleic acid (LA) intake levels on health outcomes have not been studied extensively. This study investigated the effects of high-fat diets containing different weight ratios of coconut and corn oil with LA levels of <1.00% of energy (very low LA), 2.80% of energy (low LA), 5.80% of energy (moderate LA), and 9.70% of energy (high LA) on fat deposition and selected metabolic biomarkers of male Sprague-Dawley rats. Their initial and terminal body weights are recorded. Blood, adipose tissue, and liver samples are obtained for analysis after an 8-week feeding intervention. Compared with the very low-LA diet, the high-LA diet resulted in higher body weight gain and epididymal fat deposition. No significant differences are observed in liver-to-body weight ratio, blood glucose, visfatin, and leptin levels between the test diets. Serum tumor necrosis factor-alpha (TNF-α), insulin, and C-peptide levels do not significantly increase with the increase in dietary LA levels. High-LA diet results in higher LA levels in the liver and adipose tissue. It is concluded that a high-fat diet containing high LA levels induced body weight gain and epididymal fat deposition in rats but has no effect on selected metabolic biomarkers. Practical applications: Linoleic acid (LA) (C18:2) plays an important role as one of the nutritional elements to meet the daily essential fatty acid requirements. However, a full understanding is perplexed by the various ways that LA can be included in the diet when there is a recommendation to substitute saturated fatty acid (SFA), trans- or n-3 fatty acids intake. The data provide additional findings on the effects of excessive dietary intake of LA (C18:2) on fat deposition when different levels of SFAs are replaced.     

Liver Fatty Acid Binding Protein Gene-Ablation Exacerbates Weight Gain in High-Fat Fed Female Mice

Loss of liver fatty acid binding protein (L‐FABP) decreases long chain fatty acid uptake and oxidation in primary hepatocytes and in vivo. On this basis, L‐FABP gene ablation would potentiate high‐fat diet‐induced weight gain and weight gain/energy intake. While this was indeed the case when L‐FABP null (?/?) mice on the C57BL/6NCr background were pair‐fed a high‐fat diet, whether this would also be observed under high‐fat diet fed ad libitum was not known. Therefore, this possibility was examined in female L‐FABP (?/?) mice on the same background. L‐FABP (?/?) mice consumed equal amounts of defined high‐fat or isocaloric control diets fed ad libitum. However, on the ad libitum‐fed high‐fat diet the L‐FABP (?/?) mice exhibited: (1) decreased hepatic long chain fatty acid (LCFA) β‐oxidation as indicated by lower serum β‐hydroxybutyrate level; (2) decreased hepatic protein levels of key enzymes mitochondrial (rate limiting carnitine palmitoyl acyltransferase A1, CPT1A; HMG‐CoA synthase) and peroxisomal (acyl CoA oxidase 1, ACOX1) LCFA β‐oxidation; (3) increased fat tissue mass (FTM) and FTM/energy intake to the greatest extent; and (4) exacerbated body weight gain, weight gain/energy intake, liver weight, and liver weight/body weight to the greatest extent. Taken together, these findings showed that L‐FABP gene‐ablation exacerbated diet‐induced weight gain and fat tissue mass gain in mice fed high‐fat diet ad libitum—consistent with the known biochemistry and cell biology of L‐FABP.     

An increase of cereal intake as an approach to weight reduction in children is effective only when accompanied by nutrition education: a randomized controlled trial

Background  

The main emphasis of dietary advice for control of obesity has been on reducing dietary fat. Increasing ready to eat cereal (RTEC) consumption could be a strategy to reduce fat intake and increase carbohydrate intake resulting in a diet with lower energy density.     

Increase of physical activity by improvement of the nutritional status

Physical activity is affected by nutritional modifications and, in turn, influences growth, cognition, social behavior, work performance and other functions. Studies in preschool children showed that: 1. A decrease in energy intake during four to seven days reduced the time allocated to energy-demanding activities and increased sedentary activities. 2. Children with mild weight deficit were more sedentary than well-nourished counterparts. 3. Children became more active when nutritional status improved. 4. A 10% reduction in energy intake reduced total energy expenditure by 15% without affecting weight gain nor basal metabolism. Studies of men working in non-mechanized agriculture showed that: 1. Dietary improvements led to faster salaried work, reduction of napping time and greater physical activity after work. 2. An increase in energy intake increased total daily energy expenditure, tending to maintain energy balance and relatively stable body weight within the cyclic variations of the agricultural year. 3. Food supplementation did not necessarily improve productivity. Other labor incentives without dietary improvements increased energy expenditure during working hours, which resulted in weight loss. In conclusion, good health and nutrition provide the biological basis for adequate physical activity that may improve cognitive development, social interactions, economic productivity and the quality of life of an individual or a population, but other incentives are required for the optimal expression of that biologic potential.     

Is a Calorie Really a Calorie? Metabolic Advantage of Low-Carbohydrate Diets

The first law of thermodynamics dictates that body mass remains constant when caloric intake equals caloric expenditure. It should be noted, however, that different diets lead to different biochemical pathways that are not equivalent when correctly compared through the laws of thermodynamics. It is inappropriate to assume that the only thing that counts in terms of food consumption and energy balance is the intake of dietary calories and weight storage. Well-controlled studies suggest that calorie content may not be as predictive of fat loss as is reduced carbohydrate consumption. Biologically speaking, a calorie is certainly not a calorie. The ideal weight loss diet, if it even exists, remains to be determined, but a high-carbohydrate/low-protein diet may be unsatisfactory for many obese individuals.     

High Dietary Fat Exacerbates Weight Gain and Obesity in Female Liver Fatty Acid Binding Protein Gene-Ablated Mice

Since liver fatty acid binding protein (L-FABP) facilitates uptake/oxidation of long-chain fatty acids in cultured transfected cells and primary hepatocytes, loss of L-FABP was expected to exacerbate weight gain and/or obesity in response to high dietary fat. Male and female wild-type (WT) and L-FABP gene-ablated mice, pair-fed a defined isocaloric control or high fat diet for 12 weeks, consumed equal amounts of food by weight and kcal. Male WT mice gained weight faster than their female WT counterparts regardless of diet. L-FABP gene ablation enhanced weight gain more in female than male mice—an effect exacerbated by high fat diet. Dual emission X-ray absorptiometry revealed high-fat fed male and female WT mice gained mostly fat tissue mass (FTM). L-FABP gene ablation increased FTM in female, but not male, mice—an effect also exacerbated by high fat diet. Concomitantly, L-FABP gene ablation decreased serum β-hydroxybutyrate in male and female mice fed the control diet and, even more so, on the high-fat diet. Thus, L-FABP gene ablation decreased fat oxidation and sensitized all mice to weight gain as whole body FTM and LTM—with the most gain observed in FTM of control vs high-fat fed female L-FABP null mice. Taken together, these results indicate loss of L-FABP exacerbates weight gain and/or obesity in response to high dietary fat.     

Impact of fat substitutes on fat intake

Dietary fat is the number one nutrition concern of Americans. In response to rising consumer demand for reduced-fat foods, the food industry has developed a multitude of nonfat, lowfat, and reduced-fat versions of regular food products. To generate reduced-fat or fat-free products that have the same organoleptic characteristics of the regular fat version, food manufactures frequently employ fat substitutes in the formulation of these foods. Fat substitutes are made from either carbohydrate, protein, or fat, or a combination of these components. Researchers have questioned the impact of fat substitutes on both fat and caloric intake. The majority of research studies in which fat substitutes were either covertly or overtly substituted for dietary fat indicate that in short-term, carefully-controlled conditions, fat substitutes can decrease both dietary fat intake and percentage of calorie intake from fat. However, individuals compensate for the caloric deficit created by the fat substitutes by increasing their consumption of other macronutrients, primarily carbohydrate. The long-term effect of fat substitutes on the fat intake of free-living individuals and weight control are unknown. People tend to eat more of a food when they know that food is reduced in fat. Fat substitutes should not be considered a substitute for sound nutrition education and a healthy lifestyle which includes regular exercise.     

Variants in the PPARGC1A Gene may Influence the Effect of Fat Intake on Resting Metabolic Rate in Obese Women

Recent studies have shown that dietary intake and genetic variants play a decisive role in the risk of obesity. Therefore, this study was designed to examine the interaction between dietary fat and PPARGC1A polymorphisms on the level of resting metabolic rate (RMR). We enrolled 288 Iranian overweight and obese women in this cross‐sectional study. We sequenced the 648 b.p. DNA in Exon 8 of PPARGC1A gene. We analyzed the two single‐nucleotide polymorphisms, namely rs11290186 and rs2970847, in this region. All participants were assessed for RMR, dietary intake, and body composition. This study demonstrated that total cholesterol and insulin levels were positively associated with T allele carriers of rs2970847. Moreover, the A‐deletion allele carrier of the rs11290186 genotype had higher triacylglycerol and insulin concentrations. The current study revealed that, after adjustment for energy intake, the AA genotype of PPARGC1A (rs11290186) had a direct association with polyunsaturated fatty acids and linoleic acid intakes. Another important finding in our study was that there was an interaction seen between fat and saturated fatty acids intake with the PPARGC1A genotypes. Women with fat intakes of more than 30% of calorie intake per day and the A‐deletion genotype had a lower RMR and RMR/fat free mass (FFM). It seems that the PPARGC1A polymorphisms lead to the downregulation of insulin signaling and subsequently insulin resistance. In addition, the interactions between the PPARGC1A polymorphisms (rs11290186) and the level of dietary fat intake probably can have an effect on RMR and RMR/FFM in obese women.     

Dietary factors associated with obesity indicators and level of sports participation in Flemish adults: a cross-sectional study

Background  

Obesity develops when energy intake continuously exceeds energy expenditure, causing a fundamental chronic energy imbalance. Societal and behavioural changes over the last decades are held responsible for the considerable increase in sedentary lifestyles and inappropriate dietary patterns. The role of dietary fat and other dietary factors in the aetiology and maintenance of excess weight is controversial. The purposes of the present study were to investigate the dietary factors associated with body mass index (BMI) and waist circumference (WC), and to analyse whether dietary intake varies between subjects with different levels of sports participation.     

Fecal bile acid excretion and composition in response to changes in dietary wheat bran,fat and calcium in the rat

The effect and possible interactive influence of different dietary amounts of wheat bran, fat and calcium on the fecal excretion, concentration and composition of bile acids was studied in Fischer-344 rats. The fecal bile acids were analyzed using gas-liquid chromatography. Dietary wheat bran increased both total bile acid excretion and fecal weight without changes in fecal bile acid concentration. The proportion of fecal hyodeoxycholic acid decreased with increasing dietary fiber, whereas that of lithocholic and deoxycholic acids increased significantly with fiber intake. The percent content of fecal chenodeoxycholic acid did not change. Increasing dietary fat led to an increase in bile acid excretion without changes in either fecal weight or bile acid concentration. In contrast, the level of dietary calcium did not affect the total excretion of bile acids. However, since calcium increased the fecal weight, it consequently diluted bile acids and decreased their fecal concentration. Dietary fat and calcium had no influence on fecal bile acid composition. There were no interactive effects of wheat bran, fat and calcium on fecal bile acids. The finding in this study that dietary fiber, fat and calcium induce significant changes in fecal bile acids may be of relevance to the potential of bile acids to promote carcinogenesis.     

Bioactivity and emerging role of short and medium chain fatty acids

Cardiovascular disease (CVD) and insulin resistance are directly linked to overweight and obesity. Thus, any dietary strategy capable of causing weight reduction will lower CVD and diabetes risk. Oils rich in medium‐chain saturated fatty acids (MCFA) are among several dietary components that may have potential in the treatment of obesity. MCFA are less energy dense and highly ketogenic compared to long‐chain saturated and unsaturated fatty acids (LCFA). MCFA also differ from LCFA in their digestive and metabolic pathways, since they are easily oxidized and utilized as energy, with little tendency to deposit as body fat. The dietary intake of short (SCFA) and medium‐chain saturated fatty acids from natural food sources is approximately 2.4 g/day and accounts for about 9% of the total saturated fatty acid (SFA) intake. Although early clinical studies with high levels of MCFA resulted in increased levels of plasma triacylglycerols (TAG) and low‐density lipoprotein cholesterol (LDL‐C), and reduced levels of high‐density lipoprotein cholesterol (HDL‐C) compared to diets enriched in unsaturated LCFA, these adverse effects have not been observed in more recent studies with smaller more realistic amounts of MCFA. The lower caloric value of SCFA and MCFA and their unique metabolic features form the basis for their clinical use in enteral and parenteral nutrition and for novel reduced calorie lipids for use in conventional food products.