Two types of birth control pills are available:
- Combination of estrogen and a progestogen.
- Only progestogen pill
With advancing scientific research, birth control pills also keep improving from time to time. So the latest oral contraceptives may not have the same side effects of earlier birth pills.
Birth pills do cause weight gain in some women, but it may not be the main reason of weight gain in all women.
When the effect of new low dose estrogen pills was studied on a group of women, it showed only a minimal weight increase. Study results indicated that 5 – 10 % of women reported weight gain while taking the pill. But similar percentage of women was shown to add weight, even though they were not on the pill.
Generally a comparison is made between the oral contraceptive pills with birth control injection, in context of weight gain problem. It is generally assumed that birth control pill; especially with higher dose of estrogen (more than 30mcgm) add more weight than the injection.
But study results have shown that women on high dose estrogen birth pill gained on an average 5.3 lb in a year, where as the females taking contraceptive shots gained average of 6.6 lb (2.2 kg) in a year. From the birth pill group, only 7% o women gained more than 10% of their body weight. And in the contraceptive injection group, 25% of women got more than 10% of their body weight. So by comparison, in the group of women on birth pill, weight gain was less and they had lesser chance of weight gain, than the women on birth control injections.
Now that birth control pills containing lower dosage of hormone estrogen are available (30 mcgm or less), the reports of weight gain are even less, when taken for a year. Some subjects have reported weight loss.
Causes of weight gain:
In higher doses of estrogen birth pill, the weight gain is due to fluid retention in the body. The chances of this side effect are more if 50-mcgm estrogen birth control pill is taken on regular basis. Because of the high dosage of hormone, substances like rennin – angiotensin (which are present in kidney) get stimulated and result in water retention. This water retention causes retention of Sodium, which results in weigh gain.
Only these higher dosage oral contraceptive are reported to cause water retention and weight gain. But pills with 30 mcgm estrogen show no weight gain or a slight weigh loss. The still lower dosage of 20 mcgm estrogen shows reduction in weight.
A study with 30 mcgm estrogen showed no major difference either in weight gain or loss than the control group. Though 30% showed one lb weigh gain, but it was same as in the placebo group. The weight gain was shown to be due to fat and there was no change in fluid retention. So with low dose of estrogen the side effect of fluid retention would be less.
If there is an increase of 5% of body weight, after taking the birth control pill for one year, the reason could be irregular glucose metabolism. So a low carb diet (with physician’s approval) should be followed to keep the weight in check.
There are also other oral contraceptives, which totally contain desogestrel as progestin and lesser amount of estrogen. With these birth pills, weight gain is not much. But other type of birth pills with norethindrone as main ingredient may show more weight gain than the desogestrel pill.
Birth pills and appetite:
Study reports show that birth pills (in higher or lower doses) have undesirable or negative effect on insulin resistance. The insulin level in the body increases due to contraceptives. Higher blood insulin levels stop our fat cells from using their energy. Thus it may cause weight gain. But every oral contraceptive consumer doesn’t gain weight, because all women are not prone to insulin resistance. Those who show increase in weight with birth pill should be tested for insulin resistance.
If there is noticeable weight gain or fluid retention after using oral contraceptive, it is better to take a pill with lower strength, like 20 mcgm or the physician should be consulted for changing to another pill. In case of insulin resistance, a low carb diet would be advisable.