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Do pregnancy and breast feeding increase basal metabolic rate?

Do pregnancy and breast feeding increase basal metabolic rate?


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Since pregnant or breastfeeding women have extra nutritional needs, does that mean they have a higher BMR?

Why I thought the conclusion would be sensible: Since BMR is the energy needed to perform body functions (breathing, respiration, homeostasis, digestion, etc), pregnant woman or breastfeeding women, because of their extra 'activity' (due to the presence of the fetus) will have a higher BMR.


Basal metabolic rate for a particular organism is determined by the amount of calories that the organism needs for basal metabolic processes (i.e. basal energy demands). Since pregnant and breastfeeding women have increased caloric requirements (i.e. increased energy demands), then that means by definition their basal metabolic rate is increased.


A pregnant woman's total energy expenditure during pregnancy is mainly because of a raised basal metabolic rate, or BMR. The energy necessity of basal metabolism is influenced by nutrition prior to pregnancy and the size of the fetus. According to a 1990 study, “Energy cost of physical activity throughout pregnancy and the first year postpartum in Dutch women with sedentary lifestyles” by Joop MA van Raaij, et al, “BMR is increasing throughout pregnancy mainly because of fetal demands.” BMR will decrease to preserve energy if maternal energy stores are too low when a woman becomes pregnant. Also, women having larger babies tend to have greater increases in their BMR and greater decreases in the rate of their energy stores than pregnant women having normal-weight or underweight babies.



This paper is a summary of the study funded by the Nestlé Foundation on the energy requirements of pregnancy (and lactation) which has been in progress in five countries during a period of about five years. The countries are Scotland, Holland, The Gambia, Thailand and the Philippines.

Clearly, neither Scotland nor Holland would come into the category of countries where energy deficiency was likely to occur in any prevalence. They seem therefore outside the remit of this workshop. Moreover, even in the three developing countries, the populations were chosen to be representative of groups where obvious malnutrition was improbable.

Thus, this whole study, by and large, is being undertaken in environments that would not be expected, on superficial grounds, to produce data of direct relevance to our immediate purposes. However, the findings do indeed have considerable practical importance since they have been obtained on two groups of adults who constitute a major proportion of those likely to benefit nutritionally from food supplementation - i.e., pregnant and lactating mothers. There is obviously a direct usefulness in having much more definitive and wide-ranging longitudinal information on the real-life extra energy needed by pregnancy and lactation which could easily have a bearing on the final conclusions and recommendations of this workshop.

It should be noted that although the Nestlé Foundation project on energy requirements initially included lactating as well as pregnant women, it became clear after some of the women had been studied that the breadth and intensity of the experimental measurements required by pregnancy alone were such that only limited information could be collected strictly on lactation. Thus, although in The Gambia fairly extensive measurements were done on some aspects of lactation, in Scotland, Holland and in Thailand, only tentative conclusions can be drawn from the lactation data, and no real attempt was made to study lactation in the Philippines.

As will become apparent, much of the information obtained in these five countries is consistent enough to provide a solid baseline from which relevant deductions can be made for present purposes.


Volume II

Basal Metabolic Rate

The basal metabolic rate (BMR) has a long history in the evaluation of thyroid function. It measures oxygen consumption under basal conditions of overnight fast and rest from mental and physical exertion. Because standard equipment for the measurement of BMR might not be readily available, the BMR can be estimated from the oxygen consumed over a timed interval by analysis of samples of expired air. The test indirectly measures metabolic energy expenditure or heat production.

Results are expressed as the percentage of deviation from normal after appropriate corrections have been made for age, gender, and body surface area. Low values are suggestive of hypothyroidism, and high values reflect thyrotoxicosis. Normal BMR ranges from negative 15% to positive 5%, most hyperthyroid patients having a BMR of positive 20% or better and hypothyroid patients commonly having a BMR of negative 20% or lower. Different clinical states are known to alter BMR. Fever, pregnancy, pheochromocytoma, adrenergic agonist drugs, cancer, congestive heart failure, acromegaly, polycythemia, and Paget’s disease of the bone are known to increase BMR. Obesity, starvation or anorexia, hypogonadism, adrenal insufficiency, Cushing’s syndrome, immobilization, and sedative drugs are known to decrease BMR.


Energy Metabolism During Human Pregnancy

AbstractThis review summarizes information regarding how human energy metabolism is affected by pregnancy, and current estimates of energy requirements during pregnancy are presented. Such estimates can be calculated using either increases in basal metabolic rate (BMR) or increases in total energy expenditure (TEE). The two modes of calculation give similar results for a complete pregnancy but different distributions of energy requirements in the three trimesters. Recent information is presented regarding the effect of pregnancy on BMR, TEE, diet-induced thermogenesis, and physical activity. The validity of energy intake (EI) data recently assessed in well-nourished pregnant women was evaluated using information regarding energy metabolism during pregnancy. The results show that underreporting of EI is common during pregnancy and indicate that additional longitudinal studies, taking the total energy budget during pregnancy into account, are needed to satisfactorily define energy requirements during the three trimesters of gestation.


How Diet & Genetics Affect Your Metabolism

According to Harvard Health, the way your metabolism works is mostly determined by your genetics. However, weight loss after pregnancy is largely determined by how many calories a woman consumes as well as her lifestyle choices, such as, if she is physically active, breastfeeding or if she can burn calories quickly in her resting phase during sleep or sitting down. A fast metabolism in the resting phase is burning more calories than a person who has a slow metabolism in the resting phase.

The metabolic rate is what measures how much energy and calories are burned in the resting or immobile phase. Genetics does influence a woman's metabolism, however, losing weight after pregnancy certainly has to do more with her lifestyle choices and whether she chooses to fuel her body with good, healthy food, drink lots of water and try to sleep and rest when the baby sleeps.


What factors increase/decrease basal metabolic rate?

crash dieting, starving or fasting &ndash eating too few kilojoules encourages the body to slow the metabolism to conserve energy. BMR can drop by up to 15 per cent. Loss of lean muscle tissue further reduces BMR. age &ndash metabolism slows with age due to loss of muscle tissue, but also due to hormonal and neurological changes.

  • AGE. lean body mass diminishes with age, slowing the BMR.
  • HEIGHT. in tall, thin people, the BMR is higher.
  • GROWTH. in children, teens and pregnant women the BMR is higher.
  • BODY COMPOSITION (gender) more lean tissue means higher BMR.
  • FEVER.
  • Stresses.
  • Environmental temperature.
  • Fasting/starvation.

Hereof, can you increase your basal metabolic rate?

The key is to push yourself. High-intensity exercise delivers a bigger, longer rise in resting metabolic rate than low- or moderate-intensity workouts. To get the benefits, try a more intense class at the gym or include short bursts of jogging during your regular walk.

What may impact a person's metabolism How can you increase your metabolism and what causes it to decrease ?)?


High-Resolution Fluorescence and Phase Microscopy in Conjunction with Micromanipulation for in Situ Study of Metabolism in Living Cells

IV LONG-WORKING-DISTANCE CONDENSER FOR MICROMANIPULATION

In the study of the changes in metabolic rate of single cells due to the presence of substrates, inhibitors, and xenobiotics ( 41 ), it is desirable to perform injections directly into the living cells being studied. Since there is a reaction often within a few seconds, the injections must be carried out on the microscope stage itself. They are performed using a micropipette mounted on a micromanipulator. In order to perform the injections properly, the cells have to be under microscopic observation by the experimenter during the procedure. This means that sufficient room (usually at least 7 cm) must be provided between the condenser lens and the object. In living cell work, an inverted microscope is used, with the condenser above and the objective below. To see the transparent cells clearly, phase contrast (or interference contrast) together with high resolution and therefore high numerical aperture has to be used. In order to attain the requisite resolution, the condenser lens must have numerical aperture of the same order as that of the objective.

The dual requirements of a high numerical aperture phase condenser together with the necessary working distance required that a special condenser be built (see Fig. 1a and b ).

Fig. 1 . Drawing (left) and photograph (right) of the fast long-working-distance phase condenser, affording phase illumination at up to 1.4 N.A. with a free working distance of 6-7 cm. The height of the assembly shown, exclusive of the Leitz lamphouse, is 460 mm. The drawing is not to scale. A: a standard Leitz lamphouse B: either a glass lens or a plastic Fresnel lens, which, together with C., images the lamp in A on the object. C: a plastic Fresnel lens D: an annular aperture which is imaged on the phase ring by the microscope objective E: a circular opaque disk that forms the inner edge of D.

It has been shown (see Ref. 1, p. 522 ) that the aberrations of the condenser lens of a microscope have no effect on the resolving power. Therefore, all that is necessary is that an aperture conjugate to the phase ring of the objective be provided, together with means for concentrating the light on the object. In order to provide enough working distance, the condenser had to be very large. Accordingly, a condenser 20 cm in diameter was assembled using Fresnel lenses for lightness ( 21 ). This condenser provides unimpaired phase observations, at the same leaving more than 7 cm free above the object for injections.


REPRODUCTION AND METABOLIC FUEL AVAILABILITY

Reproductive viability is closely linked to metabolic fuel availability ( 31). Neural mechanisms controlling the pulsatile release of gonadotropin-releasing hormone, luteinizing hormone secretion, and ovarian function respond to minute-to-minute changes in the availability of metabolic fuels. In pregnancy, ovarian steroids dramatically affect the ingestion, partitioning, and utilization of metabolic fuels. The detectors of metabolic fuel availability are under intense investigation. The sympathoadrenal system, which responds to hypoglycemia, and the central and peripheral sensors, which control food intake, are potential candidates. Evidence is mounting that leptin may serve as a detector of long-term metabolic fuel availability, signaling the presence of sufficient maternal fat stores to initiate reproduction.

Leptin has been implicated in the maturation and regulation of the reproductive system. Leptin treatment of ob/ob mice, which have a congenital deficiency of leptin and are infertile, stimulates the hypothalamic-pituitary-gonadal axis ( 32) and initiates pregnancy ( 33). Leptin also increases the serum concentrations of luteinizing hormone and ovarian and uterine weights in female mice. It is speculated that low leptin concentrations in women with extremely low body fat lead to infertility because of insufficient gonadotropin secretion ( 34). Elevated leptin concentrations in obese women do not adversely affect gonadotropin concentrations but may directly inhibit estrogen production by ovarian theca and granulosa cells and contribute to fertility problems.

Serial measurements of leptin throughout pregnancy have shown that serum leptin concentrations peak at 22–27 wk at ≈30 μg/L and then decline to 25.2 μg/L at 34–39 wk of gestation ( 35). Serum leptin per unit weight or per unit fat mass is 1.7-fold higher in pregnant women at 36 wk gestation than postpartum ( 36). Serum leptin is positively correlated with fat mass during pregnancy and postpartum. The slope of the regression of serum leptin on fat mass does not differ from that during the postpartum period, but the intercept is shifted upward. Leptin is positively correlated with gestational weight gain, but not birth weight, as reported by others ( 35, 37). During pregnancy, factors in addition to fat mass must regulate the expression of the ob gene. Between pregnancy and 3 mo postpartum, a mean 6% reduction in fat mass is associated with a 61% decrease in leptin. The decrease in leptin is partially explained by the drop in insulin, but 80% of the variation remains to be explained. Reproductive hormones such as progesterone, estrogen, and HCS are likely involved ( 38). It is now recognized that the placenta is a source of leptin. Leptin production has been detected in placental trophoblasts and amnion cells from the uteri of pregnant women ( 39) and in the syncytiotrophoblast cells of the human placenta ( 40).

In pregnant women, changes in appetite, thermogenesis, and lipid metabolism may be regulated in part by leptin. Leptin is known to inhibit the release of neuropeptide Y, a potent appetite stimulant. The elevated concentrations of leptin during pregnancy seem paradoxical, because presumably food intake is increased. The elevated leptin concentrations may actually represent a state of leptin resistance. Although there has been much speculation, the functional role of leptin in human pregnancy has yet to be elucidated.


Contents

During pregnancy, women gain weight which comprises of the products of conception (foetus, placenta, amniotic fluid), the increases of various maternal tissues (uterus, breasts, blood, extracellular extravascular fluid), and the increases in maternal fat stores. Accordingly, the energy cost of maintaining tissue mass (the basal metabolic rate, BMR), is higher in pregnancy - as are the energy costs of physical exercise. During pregnancy and lactation, numerous metabolic adjustments are needed to ensure that a constant supply of fuel (in the form of glucose and amino acids) reaches the foetus. [3]

During the first, second and third trimesters, BMR increases by (on average) 4%, 10% and 24% respectively, although different women vary considerably. Women from developing countries show a smaller increase in BMR than those from developed countries, while women with high prepregnant BMI show larger increases. Thus changes in BMR during pregnancy are largely a function of maternal nutritional status.

To sustain the foetus’ growth, the mother must continuously supply it with nutrients. Although the placenta is almost impermeable to lipids (other than free fatty acids and ketone bodies) lipid metabolism is strongly affected during pregnancy. In the first two semesters, foetal growth is minimal and her increased food intake causes fat store accumulation. In the last trimester, the foetus grows rapidly, sustained by nutrient transfer across the placenta. In this phase, the mother switches to a catabolic condition lipid stores are broken down, and glucose is the most abundant nutrient that crosses the placenta at this point. [4]

The energy requirement of a pregnant woman is the amount of energy intake from food that is needed to balance her energy expenditure, while maintaining a body size and composition and a level of physical activity consistent with good health, and with economic and social needs. This includes the energy needs associated with the deposition of tissue consistent with optimal pregnancy outcome. [1]


How Many Calories Should a Breastfeeding Mother Consume?

Earlier Research

Additional energy needs for an exclusively breastfeeding woman is approximately 670 Calories per day [1]. If gradual weight loss is required – then this should be 500 Calories per day.

Research of healthy breastfeeding women has shown that – while lactating – women have a greater energy output (

2718 Calories) than when lactation has ceased (

2528 Calories). This increase in energy output is from milk production – BMR (Basal Metabolic Rate) remains largely the same whether breastfeeding or not [2].

Where energy input from diet is not enough, tissue stores will be mobilized.

It is generally not necessary to consume extra fluids, following your body’s natural cues is sufficient to meet lactation needs (source). Although assumed, caffeine does not generally lead to a diuretic affect (reseach is inconsistent). However, caffeine can be found in breast milk, so consumption of coffee and energy drinks should be managed carefully.

Recent Research

The most recent and thorough set of research concludes that [3]

For exclusive breastfeeding through 5 months postpartum, the energy cost of lactation (based on mean milk production) is 454 Calories per day (over non-pregnant, non-lactating women). This amount takes into account the energy released from tissue stores.



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