How many extra calories does your body burn when pregnant?

Pregnancy causes several changes in a woman’s body that can increase the number of calories she needs to consume. During pregnancy, the body requires extra energy and nutrients to support the growing fetus and prepare for labor, delivery, and breastfeeding.

Calorie Needs in Pregnancy

The number of additional calories a pregnant woman needs varies based on her pre-pregnancy weight, BMI, activity level, and trimester. Here are some general guidelines on increased calorie needs during pregnancy:

  • Underweight women (BMI <18.5): +1200 calories/day in 2nd and 3rd trimester
  • Normal weight women (BMI 18.5-24.9): +340 calories/day in 2nd trimester, +450 calories/day in 3rd trimester
  • Overweight women (BMI 25-29.9): +340 calories/day in 2nd and 3rd trimesters
  • Obese women (BMI ≥30): +300 calories/day in 2nd and 3rd trimesters

As a general rule, pregnant women need an extra 300 calories per day starting in the second trimester, and an extra 500 calories per day in the third trimester when the baby is growing the fastest. However, calorie needs can vary significantly based on a woman’s individual situation.

Factors Affecting Calorie Needs

Several factors play a role in determining how many extra calories a pregnant woman’s body burns on a daily basis:

  • Pre-pregnancy weight and BMI – Underweight and overweight women have different calorie needs.
  • Trimester – Calorie needs increase progressively through pregnancy.
  • Multiple pregnancy – Carrying twins or more increases needs.
  • Age – Teen pregnancies have higher needs.
  • Activity level – Active women need more calories.
  • Individual metabolism – Each woman’s body is different.

While guidelines provide a starting point, a pregnant woman should work with her doctor to determine her specific recommended calorie intake based on her unique situation.

Where Do Extra Calories Go?

The additional calories consumed during pregnancy provide energy for several important processes:

  • Building new maternal and fetal tissues
  • Increasing maternal blood volume
  • Storing nutrients like protein, fat, and carbohydrates
  • Metabolizing nutrients and supporting metabolic processes
  • Preparing the breasts for lactation

Here is a more in-depth look at how extra calories are utilized during pregnancy:

Building New Tissues

Calories help build new tissues in both the woman’s body and the developing baby’s body. Maternal tissues that expand during pregnancy include the uterus, placenta, breast, blood, and fluid volumes. The fetus, placenta, amniotic fluid, and other products of conception require a steady supply of calories and nutrients to enable growth and development.

Increasing Blood Volume

During pregnancy, a woman’s blood volume increases by 30-50% to supply nutrients to the fetus. This accounts for approximately 450 extra calories per day in the second trimester and over 600 calories per day in the third trimester that are needed solely to create more blood.

Storing Nutrients

The body uses extra calories to store nutrients like protein, fat, and glycogen during pregnancy. Having these reserve stores helps meet the nutritional demands of labor, delivery, and breastfeeding. Glycogen stores help regulate maternal blood sugar levels and provide an alternative fuel source during labor if needed.

Metabolic Processes

Pregnancy ramps up metabolic processes in the mother’s body to provide adequate nutrition for the fetus. This increased metabolic activity requires more energy. Calories help meet this need and maintain the mother’s health.

Preparing for Lactation

Calories are needed to support breast changes in preparation for lactation. The breasts increase in size, vascularity, nerve endings, and glandular tissue, all of which require caloric energy.

Breakdown of Extra Calories by Trimester

Calorie needs progressively increase through the three trimesters of pregnancy:

  • First trimester – No significant increase needed
  • Second trimester – 340 extra calories/day
  • Third trimester – Up to 500 extra calories/day

Here is a breakdown of approximately how many extra calories are utilized each trimester:

Trimester Extra Calories/Day Calorie Breakdown
First Trimester 0-340 Mainly supports breast changes
Second Trimester 340 Supports increased blood volume and placental growth
Third Trimester Up to 500 Supports rapid fetal growth and tissue expansion

As shown, calorie needs progressively increase to support the phases of growth and development during pregnancy.

Impact of Activity Level

A pregnant woman’s activity level also impacts how many extra calories she burns. Women who maintain an active lifestyle during pregnancy need more calories compared to inactive women. Here are some estimates:

  • Sedentary: +300 calories/day in 2nd and 3rd trimesters
  • Moderately active: +350 calories/day in 2nd trimester, +500 calories/day in 3rd trimester
  • Very active: +400 calories/day in 2nd trimester, +600 calories/day in 3rd trimester

As shown, active pregnant women need 100-300 more calories per day compared to sedentary women depending on the trimester. Staying active during pregnancy offers many benefits, but requires extra calorie intake to maintain energy levels.

Sources of Calorie Intake

It is important that the extra calories consumed during pregnancy come from nutritious sources. Here are some healthy options:

  • Fruits and vegetables
  • Whole grains
  • Lean proteins
  • Dairy products
  • Nuts and seeds
  • Legumes
  • Healthy fats and oils

Pregnant women should focus on eating fresh, whole foods and getting nutrients from varied food groups. Proper nutrition provides fuel for the mother and developing baby and helps avoid excessive weight gain.

Weight Gain Goals

Consuming enough extra calories during pregnancy can help women achieve recommended weight gain goals. The Institute of Medicine provides the following weight gain guidelines based on pre-pregnancy BMI:

  • Underweight: 28-40 lbs
  • Normal weight: 25-35 lbs
  • Overweight: 15-25 lbs
  • Obese: 11-20 lbs

Eating the right amount of additional calories each day makes it more likely for women to gain an appropriate amount of weight during pregnancy.


Pregnancy increases a woman’s daily calorie needs to support fetal growth and development and changes in her body. General guidelines suggest women need 300-500 extra calories per day, but individual needs vary based on BMI, activity level, trimester, and other factors. Consuming nutritious extra calories helps fuel pregnancy in a healthy way. Tracking weight gain and discussing calorie needs with a doctor helps ensure you are eating the right amount to support you and your baby.

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