By Dr. Asnat Raziel, bariatric surgeon specializing in obesity treatment, metabolic health and healthy longevity; Director of the Multidisciplinary Center for Obesity Treatment, Assia Medical, Assuta Ramat HaChayal, Tel Aviv
Obesity in women: a path that changes with every stage of life
Obesity in women does not follow a single, uniform path. Over a lifetime, the female body goes through several periods of deep hormonal change: puberty, the reproductive years, pregnancy, the months after birth, menopause and aging. Each of these transitions affects appetite, fat distribution and insulin sensitivity. It also affects muscle mass, sleep and mood.
The reverse is also true. Obesity itself affects the menstrual cycle, ovulation, fertility and the course of pregnancy. It also raises the risk of diabetes, heart disease and certain types of cancer. That is why it makes sense to see it as a chronic disease that changes across the life cycle, not as a matter of willpower.
A clinical review published in August 2026 in the journal Obesity Pillars puts it precisely. According to the review, treating women requires a personal approach that fits the stage of life and combines lifestyle with medication. For example, a 15-year-old girl needs different care from a woman who is planning a pregnancy.
Fat tissue is an active hormonal organ
Fat tissue is not a passive storehouse of energy. It releases hormones and active substances, including leptin, adiponectin and inflammatory compounds. These substances affect the brain, liver, muscles, blood vessels and reproductive system.
Visceral fat, meaning deep belly fat around the organs, is especially harmful. The U.S. National Cancer Institute also stresses this point. This fat raises the risk of insulin resistance, type 2 diabetes, high blood pressure and fatty liver. For this reason, body mass index (BMI) is only a starting point. A full assessment also includes waist circumference, muscle mass, blood pressure, blood tests and how weight affects daily function.
Childhood and adolescence: where the path begins
Childhood obesity does not guarantee obesity in adulthood, but it greatly raises the risk. In girls, it is linked to early puberty and a first period at a young age. It is also linked to a future risk of insulin resistance.
Adolescence is also an especially sensitive time emotionally. Comments about the body, extreme diets, frequent weigh-ins and comparisons on social media all harm body image. They may even encourage eating disorders. So the goal is not to make a girl “thin.” Instead, the goal is to improve her health, fitness, sleep and self-confidence.
The evaluation usually includes blood pressure, glucose, HbA1c (glycated hemoglobin), blood fats and liver function. An irregular cycle, significant acne or excess hair growth call for testing for polycystic ovary syndrome. In suitable cases, doctors can also add medication. Regulators have approved semaglutide for treating obesity from age 12, with growth monitoring and attention to mental health.
Obesity in women during the reproductive years
Obesity and insulin resistance can disrupt the hormonal axis between the brain and the ovaries. The result is irregular cycles and ovulation that does not happen every month. Heavier bleeding and difficulty getting pregnant sometimes appear as well.
The main example of a hormonal condition that makes weight gain easier is polycystic ovary syndrome (PCOS). In May 2026, The Lancet published a global consensus that gives it a new name: PMOS, polyendocrine metabolic ovarian syndrome. The name highlights that this is a broad metabolic and hormonal disorder, not just an ovarian problem. It shows up as irregular cycles, ovulation problems, excess hair growth, acne and insulin resistance.
Excess weight is not required for the diagnosis, because the syndrome also occurs in lean women. Still, belly fat makes its symptoms worse. In some women, moderate weight loss improves insulin sensitivity, the menstrual cycle and ovulation. In addition, women with the syndrome need long-term monitoring of blood sugar, blood pressure and blood fats. You can read more in my complete guide to PCOS.
Obesity in women and fertility: weight loss helps, but it is no guarantee
Obesity reduces how often ovulation occurs and lengthens the time it takes to conceive. It also raises the risk of miscarriage and of complications during fertility treatment. According to the committee opinion of the American Society for Reproductive Medicine, weight loss may improve ovulation and the chance of a natural pregnancy.
However, weight loss does not guarantee more live births after fertility treatment. For an older woman, a long delay in treatment to reach a weight target may even cause harm. So the decision weighs age, ovarian reserve, related conditions and the time that treatment requires.
Contraception and obesity medications
A woman of reproductive age who takes obesity medication needs a clear conversation about contraception. Most obesity medications are not meant for use during pregnancy. It is also important to tell the drugs apart. According to the Wegovy label, semaglutide did not significantly change blood levels of the pill. That said, significant vomiting or diarrhea can reduce the absorption of any pill.
Tirzepatide, the active ingredient in Mounjaro and Zepbound, is different: it may reduce the absorption of birth control pills. That is why the Mounjaro label recommends switching to a non-oral method of contraception, or adding a barrier method. This advice applies for four weeks after starting treatment and for four weeks after each dose increase. This conversation matters all the more because weight loss sometimes restores ovulation, even in women who rarely ovulated before.
Planning a pregnancy: a window of opportunity for better health
The time before pregnancy is an excellent opportunity to control diabetes, blood pressure and blood fats. It is also the time to treat sleep apnea and nutritional deficiencies. Even moderate weight loss improves the mother’s starting point.
According to the Wegovy label, you should stop semaglutide at least two months before a planned pregnancy, because it stays in the body for a long time. Tirzepatide and other drugs also need to stop before pregnancy, according to your doctor’s instructions. Keep in mind that stopping treatment often leads to some weight regain, so it is worth planning ahead. Read more in my guide to weight loss drugs and pregnancy.
Pregnancy: appropriate weight gain, not weight loss
When treating obesity in women, pregnancy is not the time for treatment aimed at weight loss. Even a woman with obesity needs some weight gain, which supports the placenta, blood volume and fetal development. The American College of Obstetricians and Gynecologists describes the accepted ranges for a single pregnancy. A woman with overweight should gain about 7 to 11.5 kg, and a woman with obesity about 5 to 9 kg.
Obesity at the start of pregnancy raises the risk of gestational diabetes, preeclampsia, blood clots and cesarean delivery. Even so, regular follow-up, good nutrition and safe activity improve outcomes. A woman should stop weight loss drugs once she learns she is pregnant. Exposure early in an unplanned pregnancy is no reason to panic, but it is a reason to contact your doctor right away.
After birth and after bariatric surgery
After birth, sleep deprivation, hormonal changes and physical recovery all arrive together. Sometimes depression or anxiety join them. Weight that remains after birth can become the start of long-term obesity, especially after several pregnancies. In addition, after gestational diabetes, it is important to test blood sugar and follow up for years. The decision to restart medication depends on breastfeeding and on the specific drug, because data on some drugs during breastfeeding remain limited.
Bariatric surgery improves fertility and reduces some pregnancy risks. However, pregnancy during the period of rapid weight loss can bring nutritional deficiencies. Doctors usually recommend waiting about 12 to 18 months after surgery, until weight stabilizes. Before and during pregnancy, doctors check iron, vitamin B12, folic acid, vitamin D, calcium and protein.
Obesity in women during menopause
Many women feel that their body changes the rules at menopause. This feeling rests on a real biological shift. The SWAN study followed women through the menopause transition. At the start of the transition, the rate of fat gain doubled, and lean body mass began to decline. These changes continued until about two years after the final menstrual period. As a result, even a woman whose weight barely changes may see a larger waistline.
Menopausal hormone therapy mainly aims to relieve hot flashes and sleep problems, and it is not a weight loss drug. On the other hand, it does not necessarily cause weight gain either. Obesity raises the risk of blood clots, so doctors sometimes prefer estrogen through the skin. For nutrition, the foundation is a Mediterranean diet, and for exercise, the focus is on strength training. You can read more in my guide to obesity treatment during menopause.
Obesity in women and cancer risk
Excess fat tissue affects levels of estrogen, insulin and growth factors, and it increases chronic inflammation. According to the National Cancer Institute, overweight and obesity are linked to at least 13 types of cancer. These include endometrial cancer, postmenopausal breast cancer and ovarian cancer. For endometrial cancer, severe obesity carries roughly a sevenfold higher risk. Overweight or obesity carries a two- to fourfold higher risk.
This link does not mean that every woman with obesity will develop cancer. Rather, it shows that treating obesity is part of preventive medicine, alongside standard cancer screening. Also, uterine bleeding after menopause always needs a medical evaluation.
Older age: from managing weight to protecting function
For older women, it is important not to focus only on the number on the scale. Aging, falling estrogen and less activity sometimes lead to sarcopenic obesity: excess fat together with low muscle mass and strength. This combination raises the risk of falls, frailty and loss of independence. The ESPEN and EASO consensus states that diagnosis should assess muscle function and body composition, not just weight.
Treatment includes resistance training, enough protein, vitamin D as needed and work on balance. With obesity medications, it is important to keep track of eating, fluid intake, muscle strength and the pace of weight loss.
Bottom line: obesity in women needs care that fits the journey of life
Women’s health does not begin with pregnancy and does not end at menopause. Obesity in women can last for decades, but the risks and goals of treatment change over time. For a teenage girl, we protect growth and mental health. In the reproductive years, we also think about the menstrual cycle and contraception. After birth, we offer gradual support, and at menopause, we focus on belly fat, the heart and bones. Finally, in older age, we put muscle and independence at the center.
The right question is not which drug causes the most weight loss. Instead, it is which strategy suits this woman, at this point in her life.
The information in this article is general and does not replace personal medical advice.
References
Obesity and reproduction: a committee opinion
Obesity in Pregnancy: ACOG Practice Bulletin, Number 230
WEGOVY (semaglutide) injection – Prescribing Information
MOUNJARO (tirzepatide) injection – Prescribing Information
Changes in body composition and weight during the menopause transition
Definition and diagnostic criteria for sarcopenic obesity: ESPEN and EASO consensus statement
