Hormones and Weight Gain – The True Role of Estrogen and Progesterone in the process

Hormone Imbalance Prevents Weight Loss

According to the American Census Bureau in 2003, there are 57 million women in the US between the ages of 35-65. An estimated 75% of women in this age range have some form of hormone imbalance. Since hormone imbalance directly affects metabolism, you can be eating right and exercising and not successfully lose or maintain your weight.

Over the past 20 years of clinical practice one of the most common daily responses I hear from patients when discussing hormone replacement therapy is, “Will it make me gain weight?”

Fear of weight gain is one of the most common reasons women are noncompliant with hormone replacement therapy (HRT). Without question most women consider weight gain to be cosmetically unacceptable. Moreover, excess body weight alone can lead to a significant number of  chronic health problems such as cardiovascular disease and breast cancer to name a few.

Menopause in general  is associated with a decrease in the resting metabolism that reduces our ability to efficiently burn calories and hence increases body weight. A number of studies have shown that weight gain is greatest in the peri-menopausal years. There also appears to be a very unfavorable redistribution of body at the time of the menopause,  the “pear shape” which basically increases the waist-to-hip ratio.

Although it is a common belief that HRT inevitably causes weight gain, available evidence from multiple clinical trials and scientific papers suggests that this is just not true. Taking hormones, or the more appropriate statement should be,  correcting hormone deficiencies by using bio-identical hormones does not cause weight gain. Of note is that hormone replacement should be of the appropriate amount and type to correct the deficiencies in each patient.

Perhaps one of the largest women’s health studies investigating various hormone replacement regimens is the Postmenopausal Estrogen: Progestin Interventions: the (PEPI) trial.
This study  demonstrated the effect of taking replacement hormones on weight in addition to other health related issues such as the risk for cardiovascular disease. None of the groups of women on hormone replacement in any of the published articles of the PEPI Trial reported any weight gain. Another study found that post-menopausal women NOT taking hormones have a higher percentage of body fat than women who do take hormones.

In summary, it is the lack of hormone balance that can cause weight gain. Additionally, excessive levels of certain hormones, such as cortisol or insulin, cause increase in weight. Hormone balance helps you loose excess body fat more readily.

1. Weight gain and hormone replacement therapy: Are women’s fears justified?
Ineke van Seumeren * Uni6ersity Hospital Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands   http://www.laboratoriosilesia.com/upfiles/sibi/GI0507452.pdf

Declining Progesterone

Since hormone imbalance of any kind can affect our metabolism, it is of no surprise the imbalances of the menopausal and perimenopausal period are no exception. With the onset of menopause progesterone is the first of the three sex hormones (progesterone, estrogen and testosterone) to decline or become imbalanced. In fact, progesterone levels decline 120 times more rapidly than estrogen levels. The imbalance of estrogen to progesterone is medically termed “estrogen dominance.” Too much estrogen with too little progesterone is the culprit responsible for the more subtle (or less well recognized/diagnosed) symptoms of hormone imbalance such as sleep disturbances, foggy thinking and abdominal weight gain. When estrogen is dominating, insulin (produced by our pancreas and helps with blood sugar control) can be released more rapidly and more often. This in turn can lead to food cravings and fat storage.

Progesterone deficiency typically begins around age 35. There are numerous  physical, gynecological and psycho-emotional symptoms related to the decline in progesterone levels:


  • Weight gain
  • Low body temp
  • Headaches
  • Hypothyroidism
  • Hair loss
  • Fluid retention
  • Allergies/Sinusitis
  • Bone Loss


  • Breast pain/cysts
  • PMS
  • Fibroids
  • Heavy cycles
  • Irregular cycles
  • Endometriosis
  • Cramps


  • Anxiety
  • Depression
  • Irritability
  • Tendency to be stressed easily

Progesterone Deficiency Slows Metabolism

As noted above, menopause in general  is associated with a decrease in the resting metabolism that reduces our ability to efficiently burn calories and hence increases body weight. Progesterone plays several crucial roles related to weight gain and change in menopausal women’s metabolism.

  1. Progesterone works in conjunction with thyroid gland; it helps carry thyroid hormone to specific thyroid hormone receptors in order to be utilized. We all know that our thyroid controls our metabolism but with out adequate progesterone we may not use our thyroid hormone effectively. The result is storing the calories we eat as fat versus burning them for energy.
  2. Estrogen dominance from a lack of adequate progesterone inhibits the conversion of thyroid hormone, T4, into T3. This is really important because we need our T4 to convert to T3 because T3 is the active form of thyroid hormone that gives us effects of the wonderful properties of the thyroid hormones. Specifically, we need optimal T3 levels to keep our metabolism revved up to a normal level, not slowed down.
  3. Women that tend to gain a lot of water weight before their period are progesterone deficient. This is because progesterone is a diuretic and without optimal progesterone we can bloat and accumulate premenstrual water weight gain.
  4. Progesterone is also thermogenic, which means that it raises the body temperature and slightly increases metabolism.

In addition to its effect on weight, progesterone can also help protect against heart disease and breast cancer, addresses many menstrual cycle problems, improves mood and sleep, is a bone building hormone and is a very helpful with control of PMS. Since progesterone plays important roles in our metabolism, we need to have optimal levels and to make sure that our estrogen and progesterone are nicely balanced. As with any hormone, a deficiency creates symptoms while an excessive level causes symptoms as well. Too much progesterone may impede weight loss while normal levels enhance weight management. Women make an average of about 15-25 mg of progesterone during the 2nd two weeks of their cycle. Most physicians that prescribe progesterone typically start with 20mg of progesterone cream. It is important to know your hormone levels. Hormone testing, such as saliva testing can take the guess work out of hormone balance.

Key Points Regarding Progesterone and Metabolism

  • An imbalance (excess or deficiency) in any hormone interferes with metabolism.
  • Balanced hormones facilitate weight loss and control.
  • Taking hormones does not cause weight gain.
  • Progesterone is the first sex hormone that declines and does so in our thirties.
  • Progesterone deficiency triggers numerous symptoms including weight gain.
  • Excessive progesterone levels may slow metabolism.
  • The solution is to have a normal progesterone level and proper progesterone balance with estrogen.
  • Hormone testing can identify hormone imbalances.

Kritz-Silverstein D, Barrett-Connor E. “Long-term postmenopausal hormone use, obesity, and fat distribution in older women,” JAMA 1996 Jan 3; 275(1):46-9.