The Biggest Loser? – Weight Gain and Loss During Pregnancy

You may be familiar with the reality television show “The Biggest Loser”. This show centers on overweight and obese contestants attempting to lose the most weight in a battle to win the cash prize. There is no minimum or maximum weight limit for the show but most females tend to weigh over 250lb and have a body mass index (BMI) above 44. Contestants usually lose 30 to 60 percent of their weight during the 13 weeks of the show. If you are wondering whether a pregnant woman could possibly win the show given the weight gain and loss involved, the answer is “most likely not”. It turns out that during pregnancy most women put on and lose somewhere between 22lb and 28lb.

Where does all the “new” weight go?
The website Babycentre provides interesting information about weight gain during pregnancy. Bear in mind that there is a great deal of variability from woman to woman and from baby to baby. Therefore, these may not apply to you!

• By the time you reach your due date, just over a third of the weight you gained during pregnancy is from your baby, the placenta, and the amniotic fluid.
• At birth, an average baby weighs about 7.3lb.
• The placenta, which keeps your baby nourished, weighs approximately 1.5lb.
• The amniotic fluid, which supports and cushions your baby, weighs about 1.8lb.

The other two thirds of extra weight is due to the changes that happen to your body while you’re pregnant. On average:

• The muscle layer of your womb (uterus) grows dramatically, and weighs an extra 2lb.
• Your blood volume increases, and weighs an extra 2.6lb.
• You have extra fluid in your body, weighing about 2.6lb.
• Your breasts weigh an extra 0.9lb.
• You store fat, about 8.8lb, to give you energy for breastfeeding.

Losing weight in pregnancy
Women who suffer nausea and vomiting during early pregnancy may experience decreased appetite and weight loss. Usually, this has no impact on the baby’s development. By week 14 or so, nausea and vomiting should subside and appetite will likely return. At this point, the majority of women who lost weight early on quickly regain it.

The only time weight loss is a problem is if it becomes more than 10 percent of your overall body weight (for example, for a woman that weighs 150 pounds, this would mean dropping to less than 135 pounds). If this happens, your health care provider will probably prescribe a treatment to ease your nausea and vomiting.

Your nutrition targets by trimester
We often receive questions from women who are overweight or obese during pregnancy on how to maintain a well-balanced diet across all of the food groups. Recently, the website Ovuline published their daily dietary guidance. I hope you find it helpful!

First trimester:

Second trimester:

Third trimester:

Diego Wyszynski

Dr. Diego Wyszynski is the Founder and CEO of Pregistry. He is an expert on the effects of medications and vaccines in pregnancy and lactation and an accomplished writer, having published 3 books with Oxford University Press and more than 70 articles in medical journals. In 2017, he was selected a TEDMED Research Scholar. Diego attended the University of Buenos Aires School of Medicine and Johns Hopkins School of Public Health.