Effects of dietary sugar and of dietary fat on food intake and body fat content in rats

The long term ingestion of a sugar-rich diet (low fat) caused severe obesity in adult rats. In a separate experiment, the habitual consumption of a fat-rich diet (40% kcal from fat) also caused severe obesity. Severe obesity developed in both groups of animals even though they did not overeat. Voluntary food intake for the sugar-fed rats averaged 28,314 +/- 756 calories/rat per 55 wks which was similar to the value of 28,884 +/- 953 calories/rat per 55 wks for the fat-fed rats. However, both values were lower than that of 32,869 +/- 588 for the control rats eating Purina chow. Despite a lower caloric intake, carcass fat averaged 45 +/- 1% for rats eating the sugar-rich diet and 46 +/- 2% for rats eating the fat-rich diet, but only 33 +/- 2% for rats eating a diet of Purina chow. These results provide evidence that severe obesity can develop in the absence of hyperphagia in animals eating a sugar-rich or fat-rich diet. Finally, a rat model for severe obesity is presented in which carcass fat ranged from 18% (lean) to 61% (severe obesity) using dietary intervention alone at critical stages of the animal's life.     

甘肃裕固族青少年皮褶厚度及体脂含量分析

目的:了解甘肃裕固族青少年皮褶厚度和体成分的发育规律和特点.方法:2006年抽样测量甘肃989名7～17岁裕固族学生身高、体质量、肱三头肌皮褶和肩胛下皮褶厚度,分析身体质量指数(BMI)值,估测身体密度,计算体成分,利用长岭和Brozek公式估测体成分.结果:裕固族男生肱三头肌皮褶厚度11岁时达高峰(12.37 mm),其后逐步下降;肩胛下皮褶厚度在11岁时达到11.29mm,后又逐渐下降,当到达青春期后又较快速地增长.女生2处皮褶厚度呈持续增长,尤以青春中后期(12～15岁)增幅显著,并一直高于男生,且差值越来越大.裕固族男生的体脂率11岁时达最高值为20.29％,其后不断下降,女生的体脂率总体趋势是不断增加,且一直明显高于男生,男、女性之间有明显的差异.男性2处皮褶厚度之和与其他群体相比,随着年龄变化,逐渐缓慢增加,在青春后期增加迅速,超越其他民族群体.女性2处皮褶厚度变化趋势在青春期较快增加,在青春后期增长趋势放缓.男、女性BMI值随着年龄变化,逐渐缓慢增加,在青春后期持续增加,超越其他民族群体,男、女之间无差异.建立2处皮褶厚度之和百分位数参照值,其整体趋势低于汉族学生,与其他民族群体比较为中等.结论:应加强宣传,注重合理均衡饮食,尤其要积极预防青春后期肥胖的发生.     

The relationship of body fat distribution to non-insulin-dependent diabetes mellitus in a Navajo community

The relationship between non-insulin-dependent diabetes mellitus (NIDDM) and body fat distribution (BFD) as measured by waist/hip circumference (WHR) was investigated in a Navajo community. A sample of 136 females and 89 males, 20 years and older, was recruited using a cluster-sampling design. Fifty percent of the females and 30.3% of the males are overweight [body mass index (BMI) equivalent of >120% ideal body weight]. Prevalence of NIDDM is 14% in females and 10.1% in males. The sample is characterized by central BFD (mean WHR=0.897±0.075, females and mean WHR=0.963±0.071, males). WHR is significantly related to age and BMI in males (P < 0.05), but not in females. Adjusted odds ratios for risk of NIDDM prevalence with increasing WHR category were estimated from a multiple logistic regression model which controlled for age and BMI. The odds ratio and 95% confidence interval (95% CI) is 2.19 (1.14, 4.19) for risk of NIDDM prevalence for a female in the middle BFD category compared to a female in the low BFD category. Risk increases to 3.63 (95% CI=1.25, 10.52) for a female in the highest BFD category. Although there is an increased risk of NIDDM prevalence with central BFD for males, it is not statistically significant. Preferential energy storage in abdominal fat depots may be a phenotypic expression of the “Thrifty Genotype,” which places American Indians at greater risk for metabolic disorders.     

Hepatitis virus infection in an isolated canadian inuit (Eskimo) population

The epidemiology of Hepatitis A virus (HAV) and hepatitis B virus (HBV) infection was studied in a northern Canadian Inuit (Eskimo) settlement. Sera from 720 of the 850 inhabitants of Baker Lake, Canada, were tested for markers of HAV and HBV infection. Anti-HAV was present in 71% of the residents and its prevalence increased with age. Serologic evidence of HBV infections was found in 27% of residents. The prevalence increased with age, being uncommon under the age of 20 (6%)and almost universal over the age of 60 (93%). Among the 29 hepatitis B surface antigen (HBsAg) carriers identified, all were adults, all had low levels of HBsAg, and all were negative for hepatitis B e antigen (HBeAg) and DNA polymerase but positive for antibody to HBeAg. These data demonstrate a high prevalence of HAV and HBV infection in this population. Further, they suggest that a dramatic decrease in the transmission of HRV infection has occurred over the past 20–30 years.     

Effects of ambient temperature and body fat content on maternal litter reduction in Syrian hamsters

Reproduction in Syrian hamsters is sensitive to the general availability of metabolic energy. For example, females often modify their litter size by cannibalism on days 1-7 postpartum, and the number of young eaten is a function of the total supply of metabolic energy as determined by both food supply and body fat content. If the level of cannibalism is a function of energy availability, it might be expected that a drop in ambient temperature would increase cannibalism, since cold acclimation demands greater energy expenditure. We found that hamsters ate significantly more of their offspring when housed at 10 compared to 22 degrees C during lactation. The effect of cold on cannibalism was attenuated in hamsters fattened prior to cold exposure and exaggerated in hamsters that were lean prior to cold exposure. Thus, the litter size maintained by Syrian hamsters is a function of the total supply of metabolic fuels as determined by energy sources, such as food supply and adipose tissue, and by energetic costs of thermoregulatory and other processes.     

Influence of early undernutrition in rats on their body fat and RNA content in VMH neurons.

The RNA content of the ventromedial hypothalamus (VMH) and lateral hypothalamic area (LHA) neurons, and the epididymal, retroperitoneal, and liver fat content of 150-day-old male rats submitted to neonatal undernutrition, were investigated. The neonatal undernutrition was carried out by two different ways. First, by reducing the litters to two pups per nest from birth to weaning. The pups from normal litters (eight pups/nest) served as controls. Secondly, by separating half of the pups (four pups) from normal litters for 8 h daily during the first 5 postnatal days. The remaining nonseparated pups served as their controls. The data show that both groups of early undernourished pups had a significantly increased RNA content in the VMH neurons (RNA content in the LHA neurons was unchanged) and a significantly decreased epididymal, retroperitoneal, and liver fat content in comparison with their controls. The results indicate that early undernutrition leads to a permanent increase in the functional activity of VMH and alteration in fat metabolism in rats.     

Genes and body fat

This paper reviews recent data concerning the role of inherited differences in body fat content. The heritability of percent body fat or fat mass reaches about 25% of the age and gender adjusted phenotypic variance. One study has reported a significant major gene effect accounting for almost one half of the variance in body fat content. Experimental overfeeding studies suggest that body weight and fat gains are influenced by undefined genetic characteristics. Significant heritability estimates have been reported for major determinants of body fat content, including fat content of the diet, resting metabolic rate, thermic response to food, and level of habitual physical activity. Animal genetic studies and other experimental approaches indicate that the number of genes affecting body fat content, and associated with the susceptibility to obesity, is likely to be high. Currently available research strategies along with more extensive intermediate phenotyping will advance our knowledge about the genetic basis of human obesity. © 1993 Wiley-Liss, Inc.     

Basal metabolic rate of inuit

Basal metabolic rates (BMR) at the end of the winter of 1981–1982 were determined in both Inuit and subjects of European ancestry resident in Igloolik, N.W.T. (69°40'N, 81°W). Values for the Inuit sample (22 females, 14–53 years, and 30 males, 14–70 years) exceeded published body surface area norms by some 16–18%; they also exceeded the body mass norms of Schofield (1985) by 9–10%. In contrast, readings on the six subjects of European ancestry, obtained by the same observer, using the same Douglas bag technique, agreed closely with both sets of published norms. When data were expressed per unit of lean body mass, values were again 10–12% higher in the Inuit. Concomitant recordings of heart rate did not suggest that the BMRs of the Inuit subjects were increased by anxiety. Contrary to findings in the subjects of European ancestry, BMRs appeared to be higher in the elderly than in young and middle-age Inuit. This could reflect two consequences of a more traditional lifestyle among the older members of the Igloolik population: greater exposure to a very cold external environment, and greater consumption of “country” foods rich in protein and fat. © 1995 Wiley-Liss, Inc.     

Characteristics of body fat, body fat percentage and other body composition for Koreans from KNHANES IV

Accurate measurement of fat mass has become increasingly important with the increasing incidence of obesity. We assessed fat and muscle mass of Koreans with the Korea National Health and Nutrition Examination Survey IV (KNHANES IV). We studied 10,456 subjects (aged 20 to 85 yr; 4,476 men, 5,980 women). Fat and muscle mass were measured by dual-energy x-ray absorptiometry. Reference values of body compositions were obtained using the LMS method. The fat mass index (FMI, body fat mass/height(2); kg/m(2)) of Korean men did not correlate with age (P = 0.452), but those of Korean women (P < 0.001) did. The ratio of percentage of fat in the trunk and legs was positively related with age in both the genders. The appendicular lean mass/height(2) (kg/m(2)) of Korean men was negatively related to age (P < 0.001). In women, this ratio increased with age (P < 0.001). When we defined obesity according to the FMI classification, the rates of obesity were 6.1% (FMI > 9 kg/m(2)) in men and 2.7% (FMI > 13 kg/m(2)) in women. It is concluded that the muscle mass decreases and obesity increases with aging in Korean men, whereas both fat mass and obesity increase with aging in Korean women.     

Physical activity, fat intake and body fat

The body fatness of a subject is a long-term reflection of the energy balance, the more intake exceeds expenditure the more energy is stored as fat. There is not yet a clear answer on the question whether the current obesity epidemic is a consequence of gluttony or sloth. Review studies do not show a reduction of physical activity over the years, and food intake is difficult to measure in daily life conditions. Food intake can only be derived from self-report, where under-reporting of food intake and selective underreporting of fat intake are major issues. Fat intake might be an important factor in the increase of body weight. Many studies suggest the capacity of the body to oxidize dietary fat is a major risk factor for a positive energy balance. Additionally, there is evidence that most of the fat consumed is stored before oxidation. Obesity prone subjects might be characterized by a higher storage of dietary fat. The only way to increase the oxidation of dietary fat, other than consuming more dietary fat, is to increase energy expenditure by an increase of physical activity. Indeed, there are indications that physical activity is an important determinant of fat oxidation. Based on the evidence presented, it is concluded that the obesity epidemic is mainly due to a high dietary intake, especially as fat, and that physical activity can be a tool to modulate the effect of fat intake on body fat.     

Assessment of cutaneous fat and body fat by ultrasound

Summary A new rapid and simple method is introduced to measure subcutaneous fat and evaluate total body fat. It is based on real-time ultrasound and requires equipment that is used in routine examination of subcutaneous structures, e.g., thyroid gland. Results from seven regions of skin in 100 subjects correlated well with total body weight, Broca's index, and deviation from average weight 0.02>P>0.001). Comparisons were also made with measurements of subcutaneous fat from skinfolds. There was an excellent correlation of values (P<0.001 in all experiments), although ultrasound results tended to be slightly higher. For calculation of total body fat, ultrasound values were converted by regression equations to calculated skinfold thickness; when applying established mathematical models for calculating body fat from skinfold thickness results were equal in both methods (P>0.1).     

Measurement of body fat in Turner syndrome

Fourteen individuals with the Turner syndrome (gonadal dysgenesis with X chromosome chromosome abnormalities) were evaluated for obesity using hydrostatic weighing and skinfold measurements. While skinfold estimates of body fat correlated well with clinical impression, hydrostatic weighing appeared to falsely overestimate percent body fat. We suggest that reduced skeletal mass and/or occult lymphedema in Turner syndrome may invalidate the formula used to calculate percent body fat derived from hydrostatic weights. In this population and possibly in other disorders where skeletal mass is reduced from the normal, the use of hydrostatic weighing may be inappropriate.     

Immunoglobulin content and antibody activity in an artificial body cavity.

Artificial body cavities (ABC) were created by the insertion of hollow polyethylene balls in the subcutaneous tissue of rabbits. After two months no inflammatory reaction could be detected, the ABC was enveloped by a membranous structure, and the cavity contained about 20 ml of fluid. The protein concentration was about 3 times, and the IgG about 8 times, lower in the ABC fluids than in the corresponding serum. At the same time the antibody titers against sheep red blood cells (SRBC), human IgG and herpes simplex virus type 1 (HSV) were about 20 200 times lower than in the corresponding serum samples. The IgG molecules appeared to be undamaged as shown by the presence of various allotypes and by the elution pattern from G-200 column. Testing the protective activity of ABC fluids and of serum against HSV infection showed that ABC fluids had no protective activity. The experiments suggest that the membranous structure selected among classes of Ig and probably among other serum proteins. In addition, the IgG molecules with antibody activity against various inoculated antigens were selectively excluded to penetrate in the ABC. The ABC might be considered analogous to virtual cavities of the body surrounded by membranes and possibly to the extravascular compartment.     

Leptin does not reduce body fat content but augments cold defense abilities in thermoneutrally reared rat pups

 A previous study showed that recombinant leptin markedly affects the body fat content and thermoregulatory energy expenditure of lean (+/+ and +/fa) suckling-age rats, and we wanted to find out whether leptin in doses that halved body fat of cold-reared lean pups had any effect in thermoneutrally reared lean pups. When +/+ pups were artificially reared from 4 to 16 days of age at thermoneutrality and treated as before with leptin from day 7, their total metabolic rate throughout the treatment period was only 4% higher than that of the control littermates and their final body fat content only 4% lower (both P>0.05). We conclude from comparisons of the results in +/+ pups at cold and thermoneutral conditions that leptin does not stimulate, but rather disinhibits, sympathetically mediated thermoregulatory thermogenesis. Received: 26 February 1997 / Received after revision: 14 July 1997 / Accepted: 17 July 1997     

The anterior abdominal fat body

The anterior abdominal fat body is a mixture of multilocular and unilocular fat cells. It is found deep to the rectus sheath and immediately beneath the peritoneum of the anterior abdominal wall. It is first seen in the sixth month fetus as thin lobules of tissue arranged on either side of the umbilical vein but receiving blood supply from specific ensiform branches of the superior epigastric or internal thoracic artery and vein. Continued growth results in a coalescence of the bilateral lobules into a single fat body that completely overgrows the supportive blood vessels. In its cytology this body is comparable to the interscapular fat pad. It is unique in that vascular connections develop between it and the liver and in the fact that in a significant number of specimens it attains proportions that appear to represent pathological hypertrophy.     

Gastric fat content and satiety

Male rats were fitted with intragastric tubes and pyloric cuffs. Following a 15 hr food deprivation their intake of a 50% oil-water emulsion was observed to be the same whether the pyloric sphincter was occluded or not. Gastric counterinjections of normal saline (50% of the volume voluntarily drunk) did not affect the amount the subjects drank by mouth. However, when 5 ml of the stomach content was siphoned as the rats drank, an accurate compensation for the amount lost occurred. These findings indicate that the rat is capable of metering gastric triglyceride content and that satiety signals, which are not related to stomach volume, are generated by this organ.