Because metabolism influences the amount of daily energy you use, it is important to have an understanding of what may alter, either by increasing or decreasing, your metabolism. By understanding the degree of increase, you can gain a better understanding of just how much you need to eat to adequately support your baby as well as avoid unwanted and unnecessary weight gain.
Metabolism
Scientists have defined metabolism as the sum of all chemical transformations in your body most of which relate to energy production. Because energy is generally measured in calories, metabolism is often expressed in terms of the number of calories burned during inactivity or activity. In other words, pregnancy directly increases metabolism or the demand for energy production.
Adding Weight
One explanation of increased energy demand is based on weight gain. As weight gains increase throughout the pregnancy so do the energy requirements needed to perform daily tasks. In a study published by "Public Health Nutrition" that examined females with an average weight gain of 26 pounds during pregnancy, researchers found progressively increasing energy requirements from about 100 calories per day in the first trimester to about 450 by the third trimester.
Developing Child
George Brooks, author of "Exercise Physiology: Bioenergetics and Its Applications" states that another reason for the increased metabolism is related to the demand to build additional tissues for the developing child. This tissue comes from the actual baby, amniotic fluid, placenta, fetal membranes, uterus and mother's tissue estimated to be around 24 to 35 lbs by the end pregnancy. Brooks estimates the energy demands, when sitting, to increase by about 0.3 calories per minute.
Lactating
Metabolic increases don't just stop after the birth of the child, especially for lactating mothers. Carol Byrd-Bredbenner, author of "Wardlaw's Perspectives in Nutrition" suggests the energy demand during breastfeeding may actually exceed that of pregnancy reaching 500 to 800 additional calories per day. However, Byrd-Bredbenner states nearly half of the calories should come from stored fat while the remainder come from daily food intake.
References
- "Public Health Nutrition:" Energy Requirements During Pregnancy and Lactation; Nancy Butte, Janet King; Jan 2007
- "Exercise Physiology:Human Bioenergetics and Its Applications"; George Brooks, Thomas Fahey, Kenneth Baldwin; 2005
- "Wardlaw's Perspective's in Nutrition"; Carol Byrd-Bredbenner, et. al; 2009
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