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Can self-reported dieting and dietary restraint identify underreporters of energy intake in dietary surveys?

Underreporting is endemic in most dietary studies and ways to reliably identify individuals who may underreport energy intake are needed. Whether questions on self-reported dieting and dietary restraint, in addition to weight status, would identify individuals who may underreport energy intakes was examined in a United Kingdom representative survey. Mean daily energy intake was calculated from the 7-day dietary record of 668 men and 826 women. Reported physical activity was used to assign each subject's activity level and to calculate estimated energy requirements from published equations. Underreporting was calculated as estimated energy requirements minus energy intake with adjustment for daily variation. The Dutch Eating Behavior Questionnaire assessed dietary restraint. Underreporting was higher in men and women reporting current dieting than nondieters (P<0.001) and higher in high-restrained (P<0.001) than low-restrained. When stratified by body mass index category, in men these associations were only significant in the overweight (P<0.001). Dieting was associated with greater underreporting in both lean (P<0.01) and overweight women (P<0.001). Underreporting was higher in lean high-restrained women than low-restrained (P=0.02), but similar in overweight women regardless of restraint score. Questions to assess dietary restraint and current dieting may be useful tools to identify and evaluate underreporting at an individual level in dietary surveys.

Adolescent↗

Human protein requirements: interrelationships between energy intake and nitrogen balance in young men consuming the 1973 FAO/WHO safe level of egg protein, with added non-essential amino acids.

Our recent studies have shown that the 1973 FAO/WHO "safe level of intake" of egg protein (0.57 g/kg/day) is inadequate for maintaining protein nutritional status in young men receiving generous energy intakes. Therefore, an experiment was conducted to determine nitrogen (N) balance and the energy intake needed to support it when supplementary N, equivalent to 0.23 g of protein (N X 6.25)/kg/day from a nonessential amino acid mixture, was added to a diet containing 0.57 g of egg protein/kg/day. Four young men, 20 to 21 years old, participated in the 58- to 79-day metabolic N balance study. This group required significantly lower energy intakes to maintain N balance than a previously studied group fed only 0.57 g of egg protein under identical conditions. The energy intakes predicted to maintain N balance were approximately 10 to 15% less than the requirements estimate from body weight and N balance data. Present results, although based on a limited number of subjects, suggest that total N may be the limiting factor in short-term N balance at the 1973 FAO/WHO egg protein intake level for a significant proportion of young adult male populations. Long-term metabolic studies will be necessary before the practical significance of the observations can be determined.

Adult↗

Energy intake, dental caries and periodontal disease in 11-year-old black children in two regions of Southern Africa: KwaZulu and Namibia.

The study examined energy intake in relation to dental caries and periodontal disease in 11-yr-old rural and urban black children in low fluoride areas of KwaZulu and Namibia (0.15 ppm F) and one higher fluoride area of Namibia (1.56 ppm F). Twenty-four hour dietary recalls were conducted by trained interviewers and daily energy intake estimated using the MRC dietary analysis programme. DMFS was recorded according to WHO criteria: periodontal disease was measured using CPITN and SAS was used for statistical analysis. The prevalence of dental caries and periodontal disease (using CPITN), were compared within three energy groupings; < or = 850 kcal/day; > 850, < 1400 kcal/day and > or = 1400 kcal/day. The rural low fluoride Namibian children had the lowest mean energy intake (616 kcal/day), which also was the grouping with highest healthy periodontal prevalence (65%). The urban groups had higher energy intakes than the rural communities. Statistically significant effects on caries prevalence were seen for country and fluoride grouping; for periodontal disease, significant effects were noted for country, fluoride group and environment. Energy intake had no statistically significant effect, so this is not a risk marker for the disease.

Black or African American↗

Effect of fat- and sucrose-containing foods on the size of eating episodes and energy intake in lean dietary restrained and unrestrained females: potential for causing overconsumption.

OBJECTIVE: This study compared the action of high fat and high sucrose foods on snack size (satiation) and post snack satiety, in dietary unrestrained (UR) and restrained (R) lean females. DESIGN: 2 x 2 within-subjects design, each subject received each of four conditions in a counter-balanced order. SETTING: The Human Appetite Research Unit. SUBJECTS: 10 R and 10 UR lean young female students. INTERVENTIONS: Subjects consumed a low (1678 kJ) or high (2971 kJ) energy lunch, followed 2 hours later by an ad libitum snack consisting of a selection of high fat, low sucrose or high sucrose, low fat foods. Visual analogue rating scales recording subjective feelings of appetite were completed periodically. RESULTS: Energy intake at the snack was related to level of hunger (P < 0.01) and snack macronutrient composition (P < 0.001). Subjects consumed more energy when offered high fat snack foods, and more following a low energy lunch. Total group energy intake of the high fat snack selection following the low and high energy lunch was 4.39 and 3.63 MJ respectively, energy intake of the high sucrose snack selection following the low and high energy lunch was 3.03 and 2.81 MJ respectively. Post snack satiety was similar. Mean test day energy intake (including standard breakfast, fixed lunch, test snack and rest of day intake) was least when a low energy lunch was followed by an ad libitum snack of high sucrose foods. Some differences were seen between R and UR. R consumed more energy at the high fat snack following a low energy lunch, but not a high energy lunch. UR consumed more of the high fat snack following both lunch types. R consumed less energy (excluding alcoholic drinks) over the test day than UR (P < 0.05), and also less on the day following the study day (P < 0.05). R generally rated themselves as lower on measures of appetite, and rated the high fat snacks as more pleasant. CONCLUSIONS: These results indicate the energy intake of an eating episode is related to hunger level and macronutrient composition of foods consumed. High fat foods give rise to higher current energy intake than high sucrose foods, and kilojoule for kilojoule are less effective in suppressing subsequent food intake.

Adult↗

Regulation of energy intake in older adults: recent findings and implications.

Inadequate energy intake is common in older individuals and is probably the major cause of unexplained weight loss. This summary highlights recent studies on possible causes of negative energy balance in older individuals suggesting that aging is associated with a significant impairment in the regulation of food intake that inhibits appropriate short-term and long-term compensation for normal fluctuations in energy intake. The combination of a reduced ability to regulate energy intake, decreased dietary variety, and disadvantageous social factors such as functional limitations, social isolation and depression, increases the risk of negative energy balance leading to weight loss in older individuals.

Aged↗

Influence of energy intake during lactation on the interval from weaning to first estrus in sows.

A total of 191 crossbred sows were used to determine the effect of energy intake during one lactation on (1) sow and pig performance and (2) the percentage of sows in estrus by 7, 14, 21 and 70 d postweaning. Sows received 8 (Lo) or 16 (Hi) Mcal of metabolizable energy (ME)/d (Exp. 1 and 2) and 8 (Lo), 12 (Md) or 16 (Hi) Mcal of Me/d (Exp. 3) during a 28-d lactation period. All sows were fed an equal amount of crude protein, vitamins and minerals that met or exceeded the recommendations of the National Research Council. Each day after weaning, sows were fed 1.8 kg of a 14% crude protein diet and checked for estrus using boars. Serum samples were obtained weekly from sows not detected in estrus by 15 d postweaning for progesterone analysis. In Exp. 1 sows fed Lo lost more (P less than .01) weight and backfat, and weaned lighter weight (P less than .01) pigs than sows fed Hi. Fewer sows fed Lo exhibited estrus (P less than .01) by 7, 14, 12 and 70 d postweaning than sows fed Hi. In Exp. 2, sows fed Lo lost more (P less than .01) weight and backfat than sows fed Hi, but pig weaning weights did not differ. Fewer sows fed Lo expressed estrus by 7 d (P less than .01) postweaning than those fed Hi. In Exp. 3 sow weight and backfat loss decreased (P less than .01) linearly as energy intake increased. Pig weaning weights were not affected by energy intake. Fewer sows fed Lo expressed estrus (P less than or equal to .05) by 7, 14, 21 and 70 d postweaning than those fed Md and Hi. There was no difference in the percentage of sows fed Md or Hi that exhibited estrus by these time periods. Blood samples collected on d 110 of gestation and d 14 and 26 of lactation, indicated that energy intake did not influence hematocrit values, total serum protein or albumin concentrations. A significant energy intake by time interaction was observed for serum blood urea N. Three of the 25 sows bled for progesterone analysis had luteal tissue activity suggesting ovulation had occurred even in the absence of a detected behavioral estrus.

Animals↗

Does the consumption of amylase-containing gruels impact on the energy intake and growth of Congolese infants?

OBJECTIVE: To assess the effect of the incorporation of amylase in maize-based flours prepared as gruels on the energy intake and growth of Congolese infants. DESIGN: A randomised controlled trial. At 18 weeks of age, infants were randomised into either an intervention group, where they were provided with a maize/soya-based flour that contained amylase, or a control group, where they were provided with a similar flour that did not contain amylase. SETTING: Urban borough of Poto-Poto in Brazzaville, The Congo. SUBJECTS: Eighty infants (40 in each group) were randomised into intervention and control groups. Three infants in the intervention group and two controls subsequently dropped out. RESULTS: At 24 weeks, the addition of amylase resulted in a significant increase in energy intake (in kJ kg-1 day-1) from gruels without affecting breast milk consumption. In contrast, total energy intake (in kJ kg-1 day-1) did not differ significantly between groups (P= 0.08). After adjustment for morbidity and previous growth, infants in the intervention group showed better growth in length during the trial (+0.22 cm month-1; P= 0.04), especially between 24 and 31 weeks of age (+0.51 cm month-1; P< 0.01). There were no differences in weight velocity between groups. CONCLUSIONS: The findings of this study suggest that the consumption of amylase-treated gruels allows an increase in energy intake from these gruels without affecting breast milk consumption but has no impact on total daily energy intake. However, if started after 6 months, it could be effective in preventing faltering of infant linear growth.

Amylases↗

Literacy and body fatness are associated with underreporting of energy intake in US low-income women using the multiple-pass 24-hour recall: a doubly labeled water study.

OBJECTIVE: The accuracy of the multiple-pass 24-hour recall method for estimating energy intake in low-income women in the United States was ascertained by comparing the method with measurements of total energy expenditure. The multiple-pass 24-hour recall is designed to provide respondents with multiple cues and opportunities to report their food intake. It consists of 3 distinct passes: the quick list, detailed description, and review. Predictors of energy intake misreporting (energy intake--total energy expenditure) in the sample were determined. DESIGN: Four multiple-pass 24-hour recalls (2 in person, 2 by telephone) were obtained over a 14-day period to estimate energy intake. Total energy expenditure was measured over the same 14-day period using the doubly labeled water method. Body composition was measured using dual energy x-ray absorptiometry, and literacy was measured by the Wide Range Achievement Test (WRAT) for reading and spelling. SUBJECTS/SETTINGS: Thirty-five low-income women between the ages of 19 and 46 years were tested at the General Clinical Research Center at the University of Vermont, Burlington. Low income was defined as a household income at or below 130% of the federal poverty level. STATISTICAL ANALYSIS: Pearson product moment correlation coefficients, t tests, paired t tests, and stepwise multiple regression analysis were used to test the relationships among study variables. RESULTS: Mean energy intake was significantly lower than mean total energy expenditure (2,197 +/- 607 vs 2,644 +/- 503 kcal, P = .001) and the correlation between the 2 measures was poor (r = .22, P = .20). Percentage body fat and the combined age-adjusted reading and spelling WRAT scores were the best predictors of misreporting of energy intake (R = .52, P = .006). CONCLUSIONS: The multiple-pass 24-hour recall did not generate a group measure of energy intake that was accurate or unbiased in this sample. Underreporting was strongly associated with increased body fatness. The ability to read and spell as measured by the WRAT improved the accuracy of the women's recall of their food intake. APPLICATIONS: Dietetics professionals should take into consideration the problem of underreporting whenever conclusions are made about associations between diet and health and/or when evaluating the impact of food assistance programs on dietary intake.

Adipose Tissue↗

Eating together is important: using a dining room in an acute elderly medical ward increases energy intake.

AIM: To investigate the effect of eating in a supervised dining room, on nutritional intake and weight, for elderly patients on an acute medicine for the elderly ward. METHOD: Patients on the intervention ward were encouraged to attend a dining room every lunch time by a trained nursing assistant as part of the rehabilitation process. The patients on the control ward ate only by their bedside. Food intake and weight data were collected over the study period on each patient. RESULTS: Forty-eight patients participated in the study. At the lunch time meal studied the dining room group had higher intakes of energy compared with the controls [489 kcal (95% CI: 438-554) versus 360 kcal (95% CI: 289-448), P < 0.013]. There was no difference in protein intake between the groups [18.9 g (95% CI: 16.6-21.2) versus 17.7 g (95% CI: 13.2-22.2), P=0.63]. No significant difference in weight gain between the two groups was seen (P=0.6). However, there was a trend towards weight gain in the dining room group. CONCLUSION: Food intake can be improved by using a supervised dining room, and this will potentially lead to weight gain and corresponding improvements in nutritional status and rehabilitation.

Aged↗

Effect of protein and energy intake by primiparous sows during lactation on sow and litter performance and sow serum thyroxine and urea concentrations.

The effects of protein and energy intakes by primiparous sows during a 28-d lactation on thyroxine (T4) and urea concentrations in blood serum of sows, and sow and litter performance were examined in two experiments. Dietary treatments were protein intakes of 380 (LP) and 760 (HP) g of crude protein X sow-1 X d-1 and energy intakes of 8 (LE) and 16 (HE) Mcal of metabolizable energy (ME) X sow-1 X d-1 in a 2 X 2 factorial arrangement. In Exp. 1 (34 sows), neither protein nor energy intake affected serum T4 concentrations. In both experiments, serum urea concentrations during lactation were influenced by both protein (P less than .001) and energy (P less than .001) intakes. In Exp. 2 (221 sows), sows fed LP or LE lost more weight (P less than .001) during lactation than sows fed either HP or HE. Backfat loss was greater (P less than .001) in sows fed diets of LE than HE, whereas sows fed HP lost more backfat (P = .016) than sows fed LP. Pig weights on d 28 were influenced by both protein (P less than .001) and energy (P = .038), with sows that were provided high intakes of either protein or energy having heavier pigs. Litter weight at weaning was heavier (P less than .005) for sows consuming HP. Sows fed LP had larger litters at d 14 (P = .051) and 28 (P = .046) than sows fed HP. Sow energy intake had no effect on litter size or weight. Percentages of sows in estrus by 7, 14 and 35 d postweaning were higher (P less than .004, P less than .030 and P less than .060, respectively) for sows fed HP than LP, whereas sow energy intakes had no effect on the interval from weaning to first estrus.

Animals↗

Metabolic effects of altering the 24 h energy intake in man, using direct and indirect calorimetry.

1. The metabolic effects of increasing or decreasing the usual energy intake for only 1 d were assessed in eight adult volunteers. Each subject lived for 28 h in a whole-body calorimeter at 26 degrees on three separate occasions of high, medium or low energy intake. Intakes (mean +/- SEM) of 13830 +/- 475 (high), 8400 +/- 510 (medium) and 3700 +/- 359 (low) kj/24 h were eaten in three meals of identical nutrient composition. 2. Energy expenditure was measured continuously by two methods: direct calorimetry, as total heat loss partitioned into its evaporative and sensible components: and indirect calorimetry, as heat production calculated from oxygen consumption and carbon dioxide production. For the twenty-four sessions there was a mean difference of only 1.2 +/- 0.14 (SEM) % between the two estimates of 24 h energy expenditure, with heat loss being less than heat production. Since experimental error was involved in both estimates it would be wrong to ascribe greater accuracy to either one of the measures of energy expenditure. 3. Despite the wide variation in the metabolic responses of the subjects to over-eating and under-eating, in comparison with the medium intake the 24 h heat production increased significantly by 10% on the high intake and decreased by 6% on the low intake. Mean (+/- SEM) values for 24 h heat production were 8770 +/- 288, 7896 +/- 297 and 7495 +/- 253 kJ on the high, medium and low intakes respectively. The effects of over-eating were greatest at night and the resting metabolic rate remained elevated by 12% 14 h after the last meal. By contrast, during under-eating the metabolic rate at night decreased by only 1%. 4. Evaporative heat loss accounted for an average of 25% of the total heat loss at each level of intake. Changes in evaporative heat loss were +14% on the high intake and -10% on the low intake. Sensible heat loss altered by +9 and -5% on the high and low intakes respectively. 5. It is concluded that (a) the effects on 24 h energy expenditure of over-feeding for only 1 d do not differ markedly from those estimated by some other workers after several weeks of increasing the energy intake: (b) the resting metabolic rate, measured at least 14 h after the last meal, can be affected by the previous day's energy intake; (c) the zone of ambient temperature within which metabolism is minimal is probably altered by the level of energy intake.

Adult↗

Lupin-enriched bread increases satiety and reduces energy intake acutely.

BACKGROUND: Protein and fiber may be important determinants of satiety. Lupin kernel flour is a novel food ingredient that is rich in protein and fiber. OBJECTIVE: The objective was to investigate the effects of lupin kernel flour-enriched bread (LB) on satiety and energy intake in humans. DESIGN: Two randomized controlled crossover trials were performed to compare the acute effects of LB with those of white bread (WB). In study 1, the subjects (n = 16) completed 4 treatments 1 wk apart: WB breakfast (as toast) and WB lunch (as sandwiches), WB breakfast and LB lunch, LB breakfast and WB lunch, and LB breakfast and LB lunch. Energy intake at all breakfast meals was matched (1655 kJ), and ad libitum energy intake at lunch, 3 h after breakfast, was measured. In study 2, the subjects (n = 17) completed 2 treatments 1 wk apart: WB breakfast and LB breakfast (each 1655 kJ). Blood samples were taken at baseline and at regular intervals for 3 h after breakfast. RESULTS: In study 1, the LB breakfast resulted in significantly higher self-reported satiety (P < 0.001) and lower energy intake (kJ) at lunch (-488; 95% CI: -798, -178) than did the WB breakfast. The LB lunch resulted in a significantly lower within-meal energy intake (kJ) at lunch (-1028; 95% CI: -1338, -727) than did the WB lunch. In study 2, compared with the WB breakfast, the LB breakfast significantly altered the 3-h postmeal plasma ghrelin response (P = 0.04) and resulted in significantly lower mean 3-h plasma ghrelin concentrations (P = 0.009). CONCLUSION: A novel food enriched in protein and fiber derived from lupin kernel flour significantly influences energy intake acutely.

Area Under Curve↗

Metabolic interactions between surplus dietary energy intake and cigarette smoking or its cessation.

Cigarette smoking (CS) alters lipid metabolism and is associated clinically with an atherogenic lipid profile. We recently showed that, under controlled eucaloric dietary conditions, CS stimulates lipolysis without increasing oxidation of fat and that cessation of CS does not result in a rebound tendency to synthesize or store fat. We asked here whether the ad libitum intake of surplus dietary energy interacts with the metabolic effects of CS or its cessation. Eight male heavy smokers were allowed ad libitum food intake in a metabolic ward, 1 wk in CS phase and 1 wk in non-CS phase, followed by 4 wk of outpatient non-CS and a repeat 7-day study. De novo hepatic lipogenesis (DNL), lipolysis, substrate cycling of free fatty acids (FFA), hepatic glucose production, and energy expenditure were measured by using a multiple stable-isotope infusion protocol and indirect calorimetry. Surplus dietary energy intake (> 150% of predicted energy needs) occurred in five of eight subjects (2 subjs > 5,500 kcal/day, 3 subjs > 4,000 kcal/day) with weight gain of 1-4 kg/wk, but with no difference between CS and non-CS phases. Acute CS significantly increased (P < 0.05) serum FFA concentrations (58%), FFA flux (63%), and glycerol flux (36%); nonsignificantly increased extra-adipocyte (hepatic) esterification of FFA (125%, P = 0.10) and resting energy expenditure (4.1%, P = 0.22); and did not change adipocyte reesterification of FFA or whole body oxidation of fat. Basal metabolic parameters (after overnight abstention from CS) did not differ between phases. Fractional DNL correlated significantly with excess energy intake (r2 = 0.39) and with percentage of total energy needs provided by carbohydrate (r2 = 0.47). The absence or presence of CS did not affect the increase in fractional DNL in subjects with excess energy intake, however. We conclude that cessation of CS does not result in a rebound tendency to synthesis or storage of fat, even in the presence of positive short-term energy balance, contrary to previous suggestions. Moreover, stimulation of lipolysis by CS does not increase oxidation of fat and thereby protect against fat deposition under conditions of surplus energy intake. The prevention of weight gain after cessation of CS, whether or not nicotine is provided, should focus on energy balance (calorigenesis as well as intake) rather than specific alterations in lipid metabolism.

Adult↗

Effect of fat-free potato chips with and without nutrition labels on fat and energy intakes.

This study investigated the effect on fat and energy intakes of fat-free potato chips made with olestra compared with regular potato chips. Ninety-five participants (unrestrained and restrained males and females) were tested in 2 conditions. In the information condition, participants were given nutrition information about the chips and were aware that the chips differed in fat and energy contents. In the no-information condition, participants were not aware of the differences. In both conditions, participants ate either regular or fat-free potato chips ad libitum for an afternoon snack in a crossover design in two 10-d periods. To assess 24-h intake, participants completed food diaries twice in each 10-d period. The results showed that all groups significantly reduced their fat and energy intakes in the snack when eating the fat-free chips compared with the regular chips (P< 0.0001). Also, potato chip intake did not differ across time for either type of chip. Over 24 h all participants had lower fat intakes (P< 0.05) when eating the fat-free potato chips compared with the regular chips, but 24-h energy intake was not significantly different between groups. When information was provided, restrained participants ate more of the fat-free chips than the regular chips; however, this increase did not negate the reductions in fat and energy associated with eating the fat-free chips. This study showed that substituting fat-free (olestra-containing) potato chips for regular-fat chips can help reduce fat and energy intakes in short-term (within meal) situations and reduce fat intake over 24 h.

Adolescent↗

Interstitial glucose level is a significant predictor of energy intake in free-living women with healthy body weight.

The relative contribution of circulating glucose to meal-to-meal variability in energy intake is not known. In 8 free-living young (median age 26.5 y) women with healthy body weight (median BMI 22.2 kg/m(2)), we measured glucose in the interstitial space by an automated monitoring procedure (continuous glucose monitoring system, CGMS) for up to 3 consecutive days (mean 706 glucose readings per subject). We examined the association between interstitial glucose (which lags blood glucose by approximately 10 min), self-reported hunger, satiety, desire for a meal, and nutrient intakes. Participants reported consuming a typical Western diet (59% carbohydrate, 27% fat, 14% protein). Median (interquartile range) interstitial glucose was 5.2 mmol/L (4.7-5.8). Using repeated-measures techniques in univariate analyses, desire for a meal (r = 0.45, P < 0.0001), hunger (r = 0.37, P = 0.0002), satiety (r = -0.40, P < 0.0001), low interstitial absolute mean glucose up to 25 min before eating (r = -0.23, P = 0.02), and a large decline in glucose between 40 and 5 min before eating (r = -0.17, P = 0.08) were all associated with meal energy intake. In multivariate regression analyses, desire for a meal (P < 0.0001) and hunger (P = 0.02) were the strongest independent contributors to meal energy intake, whereas absolute mean glucose measured in the period 15 to 0 min before eating was marginally significant (P = 0.08). In conclusion, absolute glucose level is a significant predictor of energy intake in nonobese women. However, desire for a meal and hunger are quantitatively more important, emphasizing the importance of both glucose signals and nonglucose (internal or environmental) factors in within-subject variability in energy intake. In addition, the CGMS may have utility in understanding the role of circulating glucose in energy regulation in free-living subjects under a wide range of different nutritional conditions.

Adolescent↗

Increased energy intake in pregnant smokers does not prevent human fetal growth retardation.

A retrospective cohort study of 729 smoking and 610 nonsmoking pregnant women participating in the Prince Edward Island Prenatal Nutritional Counselling Program (1979-1989) was undertaken to study whether lower energy intake results in lower maternal weight gain and/or a higher rate of small-for-gestational-age infants (SGA) among smokers. A second objective was to quantify, using etiological fractions, the independent contributions of cigarette smoking, maternal pregravid underweight and low pregnancy weight gain to the risk of SGA. Measurements of maternal pregravid weight, height, pregnancy weight gain, smoking status, physical activity, energy intake by a series of 3-d food records throughout the duration of pregnancy, and infant birth weight were collected for women with uncomplicated pregnancies resulting in full-term singleton infants. Multiple linear regression analyses were performed to predict the effect of smoking on maternal energy intake, weight gain and infant birth weight. The independent contributions of smoking, pregravid underweight and low pregnancy weight gain to the risk of SGA were determined using logistic regression analysis. Smoking was independently associated with a higher energy intake [+702 kJ/d (+168 kcal/d)] but with lower maternal weight gain (-2.16 kg) and infant birth weight (-205 g). Dietary energy intake was positively associated with only a small increment in birth weight [5.9 g per 418 kJ (100 kcal)]. The etiologic fraction for SGA attributable to smoking was 30.8%, pregravid underweight 16.7%, and low gestational weight gain 15.3%. We conclude that the important negative effect of smoking on retarding fetal growth cannot be adequately mitigated by simply increasing energy intake.

Adolescent↗

Effect of long term differences in energy intake on metabolic rate and thyroid hormones.

Long term effects of differences in energy intake on thyroid hormone metabolism and the rate of oxygen consumption were studied in two groups of young pigs. The pigs were kept at 25 degrees C and fed either a high (H) or low (L) energy intake such that H = 2L for six weeks. The rate of oxygen consumption, the plasma levels of thyroxine (T4) and 3,5,3'-triiodothyronine (T3) and the fractional rate of disappearance of T4 and T3 were measured each week. The metabolic rate at thermal neutrality was lowest in the animals on the L intake and the critical temperature was lowest in the pigs on the H intake. These differences tended to increase with time. The fractional disappearance rate (K) for T4 began by being greater in the animals on the H intake, but after four weeks the difference reversed. The catabolic rate of T4 in nmol.kg-1h-1 showed similar changes. The k values for T3 were not significantly different between treatments. It is tentatively suggested that the different energy intakes lead to a change in the tissue sensitivity to thyroid hormone.

Animals↗

Energy intake and physical activity during pregnancy in relation to maternal fat accretion and infant birthweight.

During the second pregnancy of 56 Swedish women resulting in a term birth, energy intake and physical activity were measured for 3 days at weeks 17 and 33. The values were related to maternal lean body mass, pregnancy weight gain, maternal fat accretion and infant birthweight by multiple linear regression analyses. A significant regression coefficient was found for energy intake at week 17 on maternal fat accretion. Energy intake was not significantly correlated with infant birthweight, not even when physical activity and maternal lean body mass were taken into account. Thus in a well-nourished Swedish population, energy intake is positively related to maternal fat accretion but not to the birthweight of term infants.

Birth Weight↗