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At least 199 records · Page 11Linked to original sources

PubMed1998

Energy intake and body weight effects of six months reduced or full fat diets, as a function of dietary restraint.

OBJECTIVE: Assessment of the effect of six months consumption of reduced fat or full fat products on energy intake and body weight, as a function of dietary restraint. DESIGN: A small realistic supermarket in the University departments provided full fat commercial products and their reduced fat alternatives. Volunteers visited the supermarket once a week. Half of them were required to take the reduced fat products, the other half the full fat products. They bought additional products in normal shops. SUBJECTS: Two matched groups (age, genders, body mass index (BMI)), one dietary restrained and one dietary unrestrained, were derived from the total group of 220 healthy men and women. This resulted in four groups differing in dietary restraint and in belonging to the full fat or reduced fat group. MEASUREMENTS: Energy intake, macronutrient composition of food intake, energy density and weight of food ingested were measured before the run-in period and at 2-4 weeks, three and six months after the start of the study, by controlled food intake diaries. RESULTS: Percentage energy from fat, and energy density changed significantly, according to the reduced or full fat diet, in all subjects. Energy intake and body weight remained constant in the dietary unrestrained on a reduced fat diet and in the dietary restrained on a full fat diet. Energy intake increased significantly, with a trend of body weight increase in the dietary unrestrained on a full fat diet. Body weight decreased significantly, with a trend of decreased energy intake, in the dietary restrained on a reduced fat diet. CONCLUSION: A reduced fat diet, in combination with unrestrained eating behaviour which resulted in energy intake compensation, contributed to weight maintenance. Weight reduction was the consequence of a reduced fat diet in combination with restrained, non-compensatory eating behaviour. A full fat diet combined with unrestrained eating behaviour led to increased energy intake. Restrained eating behaviour with a full fat diet prevented an increase in energy intake and body weight. Thus dietary restraint compensated for an increase in energy density, whereas dietary unrestraint compensated for a decrease in energy density.

Adult↗

PubMed1988

Energy intake and other determinants of relative weight.

The relationships of relative weight to energy intake and to physical activity were studied among 141 females aged 34-59 y. As observed in previous studies Quetelet index (wt/ht2) was inversely related to energy intake (r = -0.11). However, obese women tended to be older (r = 0.16), exercise less (r = -0.30), and drink less alcohol (r = -0.16) than nonobese women. Older women had lower energy intake (r = -0.23) and exercised less (r = -0.12) than younger women. Energy intake and physical activity were positively related (r = 0.23). After adjustment for age, physical activity, alcohol, and smoking, the inverse correlation between relative weight and energy intake was significantly reduced (p = 0.04) from r = -0.11 to r = -0.02. Obese women reported higher intakes of total fat, and relative weight was significantly correlated with intakes of total fat (r = 0.20) and saturated fatty acids (r = 0.16). These data highlight the importance of considering factors that may confound the relationship between energy intake and obesity, and they suggest that fat intake may play a role in obesity that is independent of total energy intake.

Adult↗

PubMed1999

A clinical trial to selectively change dietary fat and/or energy intake in women: the Women's Diet Study.

Dietary fat and energy intake have been implicated in breast cancer etiology. To examine the relative importance of these dietary factors on markers of cancer risk in women, we designed an intervention trial to selectively decrease fat and/or energy intake in free-living, premenopausal women who were somewhat overweight. The study used a 2 x 2 factorial design to evaluate the independent and interactive effects of dietary fat and energy. The diets were nonintervention, low fat (15% of energy from fat, maintenance of energy intake), low energy (25% energy reduction), and combination low fat and low energy. We utilized an individualized counseling approach with self-selection of foods. Women on the low-fat and combination diets were asked to meet given daily goals for fat grams and food group exchanges, while women on the low-energy diet used only food group exchanges. Of the 113 premenopausal women randomized who were eligible for analysis, 43% were African-American. A total of 88 women completed the 12-week program, and adherence to the dietary goals was similar in both racial groups. Women on the low-fat diet were able to reduce dietary fat intake to 19% of energy by 4 weeks and to 17% by 12 weeks with a slight decrease in energy intake. Women on the low-energy diet met their energy reduction goals by four weeks while maintaining percentage of energy from fat. Women on the combination diet largely met their goals by four weeks as well. These data indicate that it is possible to selectively manipulate dietary fat and energy intake in women over a short period of time, which makes clinical studies on the relative effects of these two dietary variables on cancer risk biomarkers readily feasible.

Adult↗

PubMed1999

Behavioral and body size correlates of energy intake underreporting by obese and normal-weight women.

OBJECTIVE: To examine behavioral and body size influences on the underreporting of energy intake by obese and normal-weight women. DESIGN: Seven-day estimated food records were kept by subjects before they participated in a 49-day residential study. Self-reported energy intake was compared with energy intake required to maintain a stable body weight during the residential study (reference standard). Energy intake bias and its relationship to various body size and behavioral measures were examined. SUBJECTS: Twenty-two, healthy, normal-weight (mean body mass index [BMI] = 21.3) and obese (mean BMI = 34.2) women aged 22 to 42 years were studied. STATISTICAL ANALYSES: Analysis of variance, paired t test, simple linear regression, and Pearson correlation analyses were conducted. RESULTS: Mean energy intake from self-reported food records was underreported by normal-weight (-9.7%) and obese (-19.4%) women. BMI correlated inversely with the energy intake difference for normal-weight women (r = -.67, P = .02), whereas the Beck Depression Inventory correlated positively with the energy intake difference for obese women (r = .73, P < .01). CONCLUSION/APPLICATIONS: Results suggest that body size and behavioral traits play a role in the ability of women to accurately self-report energy intake. BMI appears to be predictive of underreporting of energy intake by normal-weight women, whereas emotional factors related to depression appear to be more determinant of underreporting for obese women. Understanding causative factors of the underreporting phenomenon will help practicing dietitians to devise appropriate and realistic diet intervention plans that clients can follow to achieve meaningful change.

Adult↗

PubMed1997

Fat gram target to achieve high energy intake in cystic fibrosis.

OBJECTIVE: Higher fat and energy intakes confer a survival advantage in cystic fibrosis (CF). There is a need to develop effective nutrition programmes that ensure optimal energy intake in CF. METHODOLOGY: A cross-sectional measurement of clinical characteristics and energy and fat intakes in patients attending the CF outpatients clinic of the John Hunter Hospital, Newcastle was undertaken. Twenty-nine subjects, mean age 12 years (range 4.3-20.2), completed weighed food records to determine the contribution of fat to the percentage of the recommended energy intake obtained and to document use of pancreatic enzyme replacement therapy. RESULTS: Diets with a high percentage of energy derived from fat did not guarantee that individuals with CF met their energy requirements. Subjects with total fat intakes of 100 g per day or greater, however, achieved in excess of 110% recommended daily intake (RDI) for energy. Up to 47% of subjects consumed more pancreatic enzyme replacement capsules than shown to give maximum effectiveness. CONCLUSION: Setting a 100 g daily fat target is a realistic way of ensuring high energy intakes in CF. Fat ready reckoners would identify the fat content of food and prescribe specific numbers of pancreatic enzyme replacement capsules to be consumed with each meal or food item.

Adolescent↗

PubMed2000

Accuracy of energy intake data estimated by a multiple-pass, 24-hour dietary recall technique.

OBJECTIVE: This study examined the accuracy of a multiple-pass, 24-hour dietary recall method for estimating energy intakes of men and women by comparing it with energy intake required for weight maintenance. DESIGN: Three-day, multiple-pass, 24-hour recalls were obtained on randomly selected days during a self-selected diet period when subjects were preparing their own meals and during a controlled diet period when all meals were provided by the study. During the dietary intervention, weight was maintained; body weight and dietary intake were monitored closely, thereby allowing estimation of the energy intake required for weight maintenance. SUBJECTS/SETTING: Seventy-eight men and women (22 to 67 years old) from the Dietary Effects on Lipoprotein and Thrombogenic Activity (DELTA) study participated in this study. All 24-hour recalls were collected using a computer-assisted, interactive, multiple-pass telephone interview technique. Energy requirements for each individual were determined by the energy content of the DELTA study foods provided to maintain weight. STATISTICAL ANALYSIS: Paired and independent t tests were conducted to examine differences among study variables. Agreement between recalled energy intake and weight maintenance energy intake was analyzed using the Bland-Altman technique. RESULTS: Compared with weight maintenance energy intake, during the self-selected diet period men and women underestimated energy intake by 11% and 13%, respectively. During the controlled diet period, men underestimated energy intake by 13%, whereas women overestimated energy by 1.3%. APPLICATIONS/CONCLUSIONS: Men had a tendency to under-estimate energy intake irrespective of the recording period. The accuracy of the recalled energy intake of women may be influenced by recording circumstances. Researchers should examine the factors influencing underreporting and overreporting by individuals and their impact on macronutrient and micronutrient intakes. Also, strategies need to be developed to minimize underreporting and overreporting.

Adult↗

PubMed1992

Energy intake and basal metabolic rate during maintenance chemotherapy.

Energy intakes and basal metabolic rates were determined in 26 children receiving chemotherapy in remission from acute lymphoblastic leukaemia or solid tumours and 26 healthy controls matched for age and sex. Body weight and height on the two groups were comparable, although one patient was stunted (height for age) and three others wasted (weight for height). Energy intake in the patients at 7705 kJ/day (1842 kcal) and controls at 7773 kJ/day (1866 kcal)) and basal metabolic rate (BMR) in the patients at 4873 kJ/day (1172 kcal) and controls 4987 kJ/day (1196 kcal) for the two groups were not significantly different. Although the energy intake:BMR ratio for both groups was 1.59, the range of values for the patient group was large (0.96-2.73) and appeared to be greater than that observed in the control group (1.23-2.46). These results demonstrated that during this period of chemotherapy there was no evidence of raised energy expenditure at rest or reduced energy intake in the patient group. No indication of undernutrition in the patients as a group was evident, although some individuals might require further clinical nutritional assessment.

Adolescent↗

PubMed2004

Short-term appetite and energy intake following imposed exercise in 9- to 10-year-old girls.

Short-term effects of different intensities of exercise-induced energy expenditure on energy intake and hunger were compared in 19 girls (10.0 +/- 0.6 years) in three conditions: sedentary, low-intensity exercise and high-intensity exercise. The exercise conditions involved cycling at 50 and 75% of peak oxygen uptake, respectively, but were designed to evoke approximately 1.50 MJ of total expenditure, as estimated from continuously monitored heart rate. A maintenance breakfast of controlled energy intake was provided and ad libitum energy intake was measured at lunch and dinner. Differences in energy intake relative to expenditure, between 09:30 and 17:00, were calculated by subtracting energy expenditure from energy intake (energy difference). Hunger, fullness and prospective consumption were rated before and after meals and exercise sessions. Lunch energy intake was significantly less after low-intensity exercise than after high-intensity exercise. Energy expenditure was greater in the exercise conditions than when sedentary and the energy difference was more positive in the sedentary condition than in each of the exercise conditions. At mid-afternoon, rated prospective consumption was less after the high-intensity exercise. The imposition of energy expenditure through exercise of either low or high intensity resulted in no detectable increase in energy intake in the short term.

Appetite↗

PubMed1995

Unexplained disturbance in body weight regulation: diagnostic outcome assessed by doubly labeled water and body composition analyses in obese patients reporting low energy intakes.

SUBJECTS: Ten patients who had long-term disturbances in body weight regulation, were referred over a 3-year period for obesity evaluation, and reported low energy intakes (< 1,200 kcal/day). OBJECTIVE: To ascertain whether these patients had a low energy expenditure and thus reduced energy requirement, and/or whether they were misreporting their energy intake. DESIGN: Comparison of outcome measures in referred patients and in obese control patients who did not report low energy intakes and disturbances in body weight regulation. MAIN OUTCOME MEASURES: Low energy expenditure was evaluated with serum thyroid hormone levels, resting metabolic rate (RMR), thermic effect of food (TEF), and total energy expenditure (TEE) by doubly labeled water technique. Misreporting of energy intake was evaluated by comparing patients' self-reported energy intake with energy intake estimated by doubly labeled water and body composition analyses over a 14-day period. STATISTICAL ANALYSES PERFORMED: Low energy expenditure was considered present in a patient if RMR or TEE was more than 15% below predicted values according to results from the control group. Patient group TEF was compared with TEF results observed in the control group. RESULTS: All patients had normal serum thyroid hormone levels. Eight patients had RMR and TEE values within 15% of predicted values and were substantially underreporting their energy intake. One patient had low TEE (-19%) and a normal RMR, a finding that implies a low level of physical activity. This patient also underreported energy intake as estimated by the doubly labeled water technique during the study (-38%). The 10th patient had a low RMR (-23.2%) and TEE (-25.0%), the mechanism of which was uncertain. This patient's reported food intake over the 14-day period was accurate but was less than her long-term intake over months or years as suggested by doubly labeled water TEE estimates. The TEF response in patients was not significantly different from that observed in the control group. CONCLUSIONS: Underreporting of energy intake from foods is a frequent finding in patients with disturbances in body weight regulation who are referred for obesity evaluation. Severe underreporting may be detectable by means of screening measures available to most dietitians. Low energy expenditure, due either to physical inactivity or to metabolic factors, is also observed. Modern evaluation methods provide new insights into patients with weight regulatory disturbances and at the same time stimulate important new research questions.

Adolescent↗

PubMed2000

Alterations in growth and body composition during puberty. IV. Energy intake estimated by the youth-adolescent food-frequency questionnaire: validation by the doubly labeled water method.

BACKGROUND: Estimates of energy intake are required for an understanding of growth and disease; however, few methods of energy intake in children have been validated. OBJECTIVE: Our objective was to validate energy intake estimated by the Youth-Adolescent Food-Frequency Questionnaire (YAQ) against the criterion total energy expenditure (TEE) by doubly labeled water (DLW). DESIGN: Twenty-three boys and 27 girls (8.6-16.2 y of age) completed the YAQ and TEE measurements in 1 y. RESULTS: Energy intake by the YAQ (10. 03 +/- 3.12 MJ) and energy expenditure by DLW (9.84 +/- 1.79 MJ) were similar (P: = 0.91) with large lower (-6.30 MJ) and upper (6.67 MJ) +/-2 SD limits of agreement. When within-subject CVs of repeated measures of the DLW and YAQ methods were used, 25 of the 50 subjects were deemed to have misreported their energy intake. The discrepancy in energy intake (YAQ - TEE) was related to body weight (r = -0.25, P: = 0.077) and percentage body fat (r = -0.24, P: = 0.09) but not to age (r = -0.07, P: = 0.63) or the time between measures. From logistic regression, fatter boys were more likely to underreport energy intake than were fatter girls. CONCLUSION: The YAQ provides an accurate estimation of mean energy intake for a group but not for an individual.

Adolescent↗

PubMed1989

Regulation of bovine adipose tissue metabolism during lactation. 5. Relationships of lipid synthesis and lipolysis with energy intake and utilization.

The effects of energy utilization during lactation on adipose tissue metabolism were determined in 51 first lactation Holstein heifers producing between 5950 and 10,246 kg milk in 305 d. Net energy intake ranged from 18.3 to 40.6 Mcal/d during 28 to 140 d of lactation. Milk yield ranged from 13.5 to 47.4 kg/d and fat percent from 1.49 to 4.60 during 28 to 140 d, providing a range of 8.2 to 32.6 Mcal/d milk energy secretion. Calculated energy balance ranged from -16.4 to 11.5 Mcal/d. Weight change ranged from -70 to 143 kg during that 112-d period. Subcutaneous adipose tissue was biopsied nine times from 30 d prepartum to 15 d after lactation ceased. Adipose lipid synthesis measured prepartum was negatively related to subsequent milk energy secretion. Net energy intake, body weight, and body weight change were related positively to adipose lipid synthesis rates from 28 to 56 d, but those rates were related negatively to milk energy secretion. Lipolysis was positively related to milk energy secretion and body weight and negatively related to NE intake. At d 60 of lactation, adipose tissue lipid synthesis rates were a function of body weight, weight gain, and net energy intake. However, catecholamine-stimulated lipolysis rates were a function of body weight and milk energy secretion. After 140 d, lipid synthesis and lipolysis were elevated and more closely related to the previous peak rather than to concomitant milk energy secretion. These relationships demonstrate the effects of dietary energy content and genetic selection for milk production on adipose tissue metabolism.

Adipose Tissue↗

PubMed1995

Interaction of acute changes in exercise energy expenditure and energy intake on resting metabolic rate.

The effects on resting metabolic rate (RMR) of energy intake and exercise energy expenditure were examined in eight trained men under four conditions: 1) high energy flux (HF), 90 min of exercise at 75% VO2max on 3 d while in energy balance; 2) low energy flux (LF), no exercise for 3 d while in energy balance; 3) negative energy balance (NEB), exercise on 3 d while consuming low-flux meals; and 4) positive energy balance (PEB), no exercise for 2 d while consuming high-flux meals. Eight untrained men were studied in LF. There were effects of exercise energy expenditure and energy intake on RMR, and an exercise x diet interaction (P < 0.05). RMR was greater in trained than in untrained subjects only when trained subjects were in HF. These data indicate that RMR is influenced by exercise, energy intake, and their interaction and suggest that higher RMR in trained vs untrained individuals results from acute effects of HF rather than from a chronic adaptation to exercise training.

Adolescent↗

PubMed1990

The relationship of eating frequency and caloric density to energy intake among rural Mexican preschool children.

The energy intake of children in a population characterized by chronic malnutrition was measured in order to examine the effects of eating frequency and caloric density. Forty-five children aged 33-60 months were each observed continuously throughout one day. Food intake was determined by weighing and all aspects of food-related behavior were recorded. The children ate on average 13.5 +/- 4 times each day. Children who ate more frequently had significantly higher energy intake than children who ate fewer than 13 times [1655 vs. 1395 kcal (6928 vs. 5839 kJ)], and the excess was consumed during snacks. The caloric density of all foods consumed averaged 121 kcal (507 kJ) per 100 g. While children served meals of low caloric density [less than 100 kcal (419 kJ) per 100 g] consumed less energy at meals than did other children [709 vs. 900 kcal (2968 vs. 3767 kJ)], they consumed more energy from snacks [917 vs. 617 kcal (3839 vs. 2583 kJ]. Thus, total energy intake did not differ significantly between children served meals of lower vs. higher caloric density.

Child Behavior↗

PubMed2001

A meta-analysis of the effect of glucagon-like peptide-1 (7-36) amide on ad libitum energy intake in humans.

Seven studies have now been published pertaining to the acute effect of iv administration of glucagon-like peptide-1 (7-36) amide on ad libitum energy intake. In four of these studies energy intake was significantly reduced following the glucagon-like peptide-1 infusion compared with saline. In the remaining studies, no significant effect of glucagon-like peptide-1 could be shown. Lack of statistical power or low glucagon-like peptide-1 infusion rate may explain these conflicting results. Our aim was to examine the effect of glucagon-like peptide-1 on subsequent energy intake using a data set composed of subject data from previous studies and from two as yet unpublished studies. Secondly, we investigated whether the effect on energy intake is dose dependent and differs between lean and overweight subjects. Raw subject data on body mass index and ad libitum energy intake were collected into a common data set (n = 115), together with study characteristics such as infusion rate, duration of infusion, etc. From four studies with comparable protocol the following subject data were included if available: plasma concentrations of glucagon-like peptide-1, subjective appetite measures, well-being, and gastric emptying rate of a meal served at the start of the glucagon-like peptide-1 infusion. Energy intake was reduced by 727 kJ (95% confidence interval, 548-908 kJ) or 11.7% during glucagon-like peptide-1 infusion. Although the absolute reduction in energy intake was higher in lean (863 kJ) (634-1091 kJ) compared with overweight subjects (487 kJ) (209-764 kJ) (P = 0.05), the relative reduction did not differ between the two groups (13.2% and 9.3%, respectively). Stepwise regression analysis showed that the glucagon-like peptide-1 infusion rate was the only independent predictor of the reduction in energy intake during glucagon-like peptide-1 (7-36) amide infusion (r = 0.4, P < 0.001). Differences in mean plasma glucagon-like peptide-1 concentration on the glucagon-like peptide-1 and placebo day (n = 43) were related to differences in feelings of prospective consumption (r = 0.40, P < 0.01), fullness (r = 0.38, P < 0.05), and hunger (r = 0.26, P = 0.09), but not to differences in ad libitum energy intake. Gastric emptying rate was significantly lower during glucagon-like peptide-1 infusion compared with saline. Finally, well-being was not influenced by the glucagon-like peptide-1 infusion. Glucagon-like peptide-1 infusion reduces energy intake dose dependently in both lean and overweight subjects. A reduced gastric emptying rate may contribute to the increased satiety induced by glucagon-like peptide-1.

Adult↗

PubMed1986

Effect of energy intake on nitrogen metabolism in nondialyzed patients with chronic renal failure.

Dietary energy requirements were evaluated during 16 studies that were carried out in six clinically stable nondialyzed chronically uremic patients who lived in a clinical research center and were fed diets providing 45, 35, 25 or 15 kcal/kg/day. Each diet was fed for 23.7 +/- 5.7 SD days and provided about 0.55 to 0.60 g protein/kg/day. Nitrogen balance after equilibration and adjusted for changes in body urea nitrogen, and change in body weight each correlated directly with energy intake. Correcting for estimated unmeasured nitrogen losses of about 0.58 g/day, nitrogen balance was negative in one of four patients fed 45 kcal/kg/day, one of five patients receiving 35 kcal/kg/day, three of five patients ingesting 25 kcal/kg/day and both patients fed 15 kcal/kg/day. The urea nitrogen appearance (UNA), the UNA divided by nitrogen intake, and several plasma amino acids, determined after an overnight fast, each correlated inversely with dietary energy intake. Resting energy expenditure measured by indirect calorimetry did not differ from normal and averaged 0.012 +/- 0.0033 kcal/kg/min with the different diets. These observations suggest that although some clinically stable nondialyzed chronically uremic patients ingesting 0.55 to 0.60 g protein/kg/day may maintain nitrogen balance with energy intakes below 30 kcal/kg/day, a dietary intake providing approximately 35 kcal/kg/day may be more likely to maintain neutral or positive nitrogen balance, maintain or increase body mass, and reduce net urea generation.

Amino Acids↗

PubMed1994

Correlates of over- and underreporting of energy intake in healthy older men and women.

The aim of this study was to determine whether variations in physiological characteristics were predictive of over- or underreporting of energy intake in older men and women. Total energy expenditure was predicted in 81 older men (66 +/- 6 y) and 56 older women (66 +/- 6 y) from a previously developed equation that uses the doubly labeled water method. The degree of over- or underreporting of energy intake was derived by subtracting predicted total daily energy expenditure from self-reported energy intake obtained from a 3-d diet record. Older women underreported energy intake (-2206 kJ/d +/- 1841) to a greater degree than did older men (-1301 kJ/d +/- 1908) (P < or = 0.01). In men, none of the physiological variables were significantly correlated with over- or underreporting of energy intake. Among the women, percent body fat was negatively correlated with underreporting of energy intake (r = -0.42, P = 0.001). Thus, the underreporting of energy intake increased with the amount of adiposity in women.

Adipose Tissue↗

PubMed1998

Effects of exercise on appetite control: loose coupling between energy expenditure and energy intake.

The relationship between physical activity and energy intake (food consumption) can take a number of forms, depending on the intensity, duration and frequency of the activity, and upon the degrees of fitness and physiological status of the individual. At extremes of energy expenditure such as those found in long distance cyclists, voluntary energy intake may be sufficient to balance the enormous daily expenditure; this is due to an entraining effect. Under more normal situations, there is a widely held belief that physical activity is a poor strategy for losing weight, since the energy expended drives up hunger and food intake to compensate for the energy deficit incurred. Recent studies in both normal weight and obese individuals show that substantial periods of exercise do not increase hunger and do not drive up food intake. Comparisons between sedentary and normally active individuals, or between enforced periods of rest or strenuous activity, generate little or no effect on levels of hunger or daily energy intake, indicating a rather loose physiological coupling between energy expenditure and food intake. This view generates an optimistic view of the role of exercise in weight loss and weight control, as it indicates that intake is not automatically driven up to compensate for energy expended. Reasons why physical activity often produces disappointing effects, rise from inappropriate food choices, a desire for self-reward after exercise and misjudgements about the relative rates at which energy can be expended (by exercise) or taken in (by eating). This means that physical activity will be most beneficial for weight control, if carried out in conjunction with a low energy dense diet or with judicious control of eating.

Appetite↗

PubMed1985

Lactational performance in relation to energy intake in the baboon.

The relationship between energy intake and lactational performance in the baboon was investigated by determining energy intake, milk output and energy balance in animals fed ad libitum during a nonreproductive phase and during lactation, or fed 80% or 60% of ad libitum intake during lactation. No evidence was found for an increased efficiency of energy utilization during lactation when feeding was ad libitum, as judged by calculated energy used on activity and maintenance. Restricted feeding did however produce an increase in efficiency, estimated at 17-25%. This change enabled milk output and body nutrient stores to be protected when the restriction was to 80% of the ad libitum intake but at 60% of ad libitum intake, milk output was reduced and body nutrient mobilization was increased. It is proposed that low maternal food intake is associated with impairment of lactational performance when it is also severe enough to increase body nutrient mobilization.

Animals↗