Many women notice that at various times of life they tend to gain weight unexpectedly. They have not changed any eating or exercise habits, yet put on 5 or 10 pounds within a short time. While there are multiple reasons for this, including thyroid issues, it frequently goes back to sex hormone imbalances.
Sometime after age 35, women stop ovulating, which means they are also not producing progesterone at the same rate as before. This can lead to a condition known as “Estrogen Dominance”. It is in this condition that progesterone can be most effective to help control weight. The female body makes both estrogen and progesterone in concert during a normal menstrual cycle. Since one of the effects of progesterone is to compete with, or “tone down” the estrogen, when it is missing the estrogen can now exert a bigger effect. One prime example of this is that estrogen tends to put weight on the body, while that tendency is decreased with the proper amount of progesterone. Another situation besides estrogen dominance where progesterone is needed is estrogen replacement in full menopause. When a menopausal woman is prescribed estrogen alone (which is common in conventional HRT for women without a uterus) she frequently has symptoms of estrogen dominance since the progesterone is again missing. This is one of the reasons we always recommend supplementing progesterone when the woman is taking estrogen.
Estrogen causes fluid retention, while progesterone, since it has a diuretic effect reduces that extra fluid. This extra water weight tends to make women feel bloated and can be 5 or more pounds.
Estrogen dominance can also increase insulin levels, which leads to sugar cravings to combat the resulting low blood sugar. By balancing the excess estrogen with progesterone, we can normalize the insulin levels leading to less carbohydrate intake, and thus normalizing weight.
When used orally, progesterone functions as a sleep aid. For women who are sleep-deprived this can be beneficial in weight control since lack of sleep interferes with leptin, the hormone which controls appetite. Sleep deprivation also has been shown to increase calorie intake and to reduce energy expenditure, leading to weight gain.
Lack of progesterone also causes the body to make more of a protein called TBG (thyroid binding globulin) which binds up thyroid hormones making them inactive. The thyroid gland is producing the correct amount of thyroid hormone, but it is not active in the body, leading to symptoms of low thyroid. One of the primary symptoms of this is weight gain.
In all these effects note that progesterone does not directly cause weight loss. Instead it reduces the effect of other hormones in the body which are causing the weight gain. Think of it as allowing rather than causing the body to lose weight.
For these reasons and others, it is important for women in peri-menopause experiencing estrogen dominance and for women who are replacing estrogen to consider using progesterone. Once again we see that balance between hormones is critical to maintaining a healthy lifestyle.