Why Am I Gaining Weight So Fast During Pregnancy?

Wow! You can see how fast this baby is growing in your belly.

You’ve been closely monitoring your baby’s growth with our pregnancy week-by-week emails.

So you know the size of your baby is good, as your belly grows accordingly each week.

Let’s take a look at this often controversial topic of gaining weight fast during pregnancy.

Gaining weight during pregnancy but not eating a lot

It can feel odd to experience weight gain when you’re not eating a lot but it does happen during pregnancy.

You might be puzzled about some things, such as experiencing morning sickness. You think you aren’t keeping down enough food to gain weight. Even so, your body is maximizing the nutrition it gets.

Or perhaps you’ve made some changes in your lifestyle habits because you were conscious about your pre-pregnancy BMI. You’ve been watching your portion sizes at meals, and snacking less on high-calorie junk food because you’re worried about gaining too much weight.

But you get on those weighing scales and wonder where all that weight is coming from.

Gaining weight fast during pregnancy

When a woman becomes pregnant her body has around 40 weeks to produce a fully formed beautiful new baby.

Most of the main body changes take place during the first trimester. This is the time during pregnancy when baby is smallest and your food intake is compromised by aversions, morning sickness, and even vomiting.

Some women with hyperemesis gravidarum even lose weight during this first part of pregnancy.

Creating a human being makes the mother’s body work hard by increasing her metabolism, to make sure her baby is perfectly developed by the time of birth.

Pregnancy isn’t just about making a baby; it’s also about preparing to give birth, and to care for and feed the baby for a long time after she’s born.

The pregnant woman’s main weight gain comes from getting her body to work efficiently, to ensure this happens.

For that extra weight to develop – in the form of a growing baby, placenta, amniotic fluid, umbilical cord, breast tissue, and fat stores – your body needs to do a lot of extra work.

It also has to pump hormones to the right receptors to do their specific job, digest the necessary food, and get appropriate rest. The circulatory system is the system responsible for that unnoticed, fast pregnancy weight gain.

A woman’s blood volume – the amount of blood that circulates in the body – increases significantly during the first few weeks of pregnancy. It keeps increasing throughout the whole pregnancy.

Blood is fluid, and blood volume increases mainly by holding onto the water you drink. Even if you don’t eat much, or manage to keep down a lot of solid food, your blood volume keeps increasing throughout the whole pregnancy.

This blood increase provides the highest of all gestational weight gain. Increased blood volume leads to rapid weight gain during pregnancy.

This is especially true in the early stages and, by the end of a healthy pregnancy, blood will have added around 8 pounds (3.6 kilograms) to your pre-pregnancy weight.

How much weight do you gain during pregnancy?

As well as the increased amount of blood adding more weight, let’s look at other ways in which pregnant women gain weight by the end of the third trimester.

The non-pregnant uterus is about the size of a small pear. Its size and weight multiply during pregnancy. This includes what is growing inside, such as the baby, the placenta, and the amniotic fluid. These keep growing in size for the whole pregnancy.

Your uterus will weigh around 2 pounds (900 grams) by the end of the third trimester and everything inside it will add approximately 11 pounds (5kg) in weight gain by the last trimester.

Not surprisingly, your breasts also gain weight. Sometimes, the size of the breasts is one of the first signs that make you suspect you’re pregnant. As the pregnancy progresses, your breasts get ready to feed your baby. This contributes to your total weight gain. By the end of your pregnancy, each breast weights 1 pound (450 grams).

One of the weight gain factors women tend to dislike the most is increased body fat. This becomes quite obvious, especially during the second and third trimesters of pregnancy.

These fat stores might make you think you’re gaining too much weight, and even going over the recommended weight gain.

You might even worry the extra weight gain will put you at higher risk of developing pregnancy-related health problems like gestational diabetes or intrauterine growth restriction.

Don’t worry. Pregnant women gain these fat deposits for a meaningful purpose and that’s to nurture their babies once they’re born.

Even if you see these fat deposits building up, you’re probably not gaining too much weight. At full term, a pregnant woman’s fat reserves weigh around 7 pounds (3 kilograms).

How much weight should you gain each trimester?

A healthy pregnancy weight gain is about 12-35 pounds (5.4-15.8 kilograms). Some publications insist on emphasizing that this depends on your pre-pregnancy weight.

Health professionals must be very careful with weight gain recommendations, especially with obese or underweight women, as their BMIs can wrongly place them in high-risk categories.

Healthcare providers have a great impact on women’s perceptions of themselves. A good professional will not only provide accurate and evidence-based care but will make sure pregnant women’s emotional needs are fully covered.

A pregnant woman should be happy overall, and healthcare professionals should ensure this is the case during each prenatal visit.

Of course, there’s evidence to show obesity can lead to complications during pregnancy, childbirth, and the postpartum period. Obesity isn’t good for your health, whether you’re pregnant or not.

Although you should be aware of the risks obesity carries, healthcare professionals should always provide the best possible individualized care.

Most pregnant women take care of their health during pregnancy. If they were overweight before becoming pregnant, their health – especially their mental health – might have suffered greatly because of this.

The same applies to underweight women, who might have followed special diets to increase their ‘normal weight’.

What should matter most is to make sure the baby develops in a healthy way, while the mother gains a reasonable amount of weight.

It’s difficult to generalize about how much weight gain is appropriate for each trimester.

First trimester weight gain

During the first trimester, compared with the other two, the weight gain doesn’t seem to be so great, as the baby is developing but not really putting on too much weight.

Remember, most of the weight gain in these early stages is related to the water weight added to your blood.

Some women might even lose weight during the first few weeks of pregnancy; this doesn’t necessarily mean there’s a health problem.

Your body fat, redistributed and conveniently stored since puberty, will make sure your baby and your body will be well-nourished, even if you’re struggling to keep food down for a few weeks.

Drinking water and keeping well hydrated is very important during pregnancy, especially at the very beginning.

In the first trimester, you might go from losing a couple of pounds to gaining around 5-6 pounds (2.2-2.7 kilograms). If you’re feeling unwell, lightheaded, or suffering from severe morning sickness or having an increased appetite that’s worrying you, make sure you contact your healthcare provider.

It’s important to check you’re getting enough essential nutrients and everything is fine with you and your baby.

Second trimester weight gain

The second trimester is usually the easiest of the whole pregnancy.

First trimester discomforts are in the past, your belly is a reasonable size and your baby is developing and gaining more weight week after week.

It’s likely you will have your appetite back, so choosing to eat healthy, nutritious foods to support your body’s changes and your growing baby is incredibly important at this time.

You might gain 1-2 pounds (450-900 grams) per week during the second trimester.

Third trimester weight gain

In the last trimester, your baby is fully developed. All she needs do is keep growing and gain weight to remain healthy and avoid birth complications.

Low energy stores can cause complications, or even mean a preterm birth, if the baby isn’t gaining weight as expected.

You could put on between 1-2.5 extra pounds ( 450 grams-1.2 kilograms) each week from mid-pregnancy onwards. This will help baby achieve a healthy birth weight.

Gaining weight in buttocks during pregnancy

The hips and buttocks are the number one place where women store most of their fat. Whenever there is weight gain it tends to go ‘straight to the hips’. This also occurs with pregnancy weight gain.

Pregnant women aren’t just growing a baby inside their bodies. They’re preparing their bodies for motherhood.

It takes a lot of physical energy to feed and nurture a baby until she can survive independently. In preparation, a mother’s body lays down stores of energy, in case of famine, to prioritize her baby’s needs.

Gaining weight in the face during pregnancy

As you gain weight all over, you’ll also notice it in your face. By the end of your pregnancy, you might be surprised to see your face looks rounder, your nose is larger, and so on.

Most often, this is water retention, known as oedema. It can make you feel heavy and fuller, and your weight increases due to the extra fluid in your cells.

Although oedema might be caused by water retention due to hormonal changes, it can also be a sign of a more serious condition.

Oedema is easily identified by pressing your skin for a few seconds with your thumb or fingers. When you remove the pressure, you can see a dent in your skin, which doesn’t disappear within a few seconds.

If this happens, check with your healthcare provider, especially if it appears on the upper half of your body.

Gaining weight in legs during pregnancy

Yes, that extra pregnancy weight also goes to your legs. Your body is storing energy for the potential lean times after birth, to ensure your baby is well nourished. Your legs are often one of the first places water retention shows up.

The blood circulation in your legs might be a bit slower, due to the increasing weight around the pelvis area. Oedema is fluid that builds up, and gravity means the extra fluid tends to travel to the lowest body parts.

Although you might have heard the solution for this is to put your feet up, check you’re doing this in the right way. Sitting on the couch with your feet up can make you lean backwards, which means your baby might find a less than ideal position in your uterus for birth.

You can read more in Posterior Baby: What It Means And How To Turn Baby.

Although oedema is common and normal during pregnancy, it can be a sign of a severe pregnancy condition called preeclampsia.

If you live in a hot climate and spend a lot of time on your feet, it’s normal for some swelling and puffiness to occur. Preeclampsia can develop rapidly with serious consequences for mother and baby if left untreated.

Contact your healthcare provider if oedema appears alongside other signs, such as headaches, blurred vision, chest pain.

You can read more about this condition in Preeclampsia: Signs, Symptoms And Causes.

Gaining weight in arms during pregnancy

Weight gained during pregnancy will go to every place in the body where it’s likely to be needed. If so, how do we explain weight gain in the arms?

If you’re prone to storing fat in your arms anyway, this is where your body might naturally send that extra weight gain during pregnancy. Even if you’re eating well and exercising, you might see a bit of that extra pregnancy weight in your arms, too.

Let’s be real here. Can you imagine your whole body getting rounder but your arms staying slim? Fat is generally evenly distributed around the body, but during pregnancy deposits are increased in certain areas of the body.

The body acts as a whole, and if you gain around 7 pounds (3 kilograms) of fat by the end of the pregnancy this will be evenly distributed across the whole body.

How to gain minimal weight while pregnant

Understanding that your weight might increase quite a lot during pregnancy doesn’t mean you should do nothing at all to control it.

It’s a very good idea to try to stay at an appropriate normal weight during pregnancy.

Keeping an eye on what you eat, making sure you choose foods wisely, and exercising during pregnancy will make sure you don’t gain too much unnecessary weight.

Exercising during pregnancy doesn’t mean you have to go all sporty. Frequent brisk walking or yoga are very good ways to keep your pregnancy weight under control.

Several studies suggest keeping a healthy eye on your weight gain during pregnancy will help you be healthier and fitter for labor. It can even shorten the length of your labor.

It can also help you avoid complications that excessive pregnancy weight gain cause, such as high blood pressure, gestational diabetes, or difficulty establishing breastfeeding once your baby is born.

Do you burn more calories when pregnant?

I guess this is where the expression ‘eating for two while pregnant’ came from. Your body is working harder and using more energy so you are burning more calories when pregnant. This doesn’t mean you need to eat in excess of your normal calorie intake.

You only need about 300 additional calories per day during pregnancy. That’s about the same as eating an avocado, so it’s not a whole lot extra.