Dr Nick Fuller
Leading Obesity Expert at the University of Sydney and founder of Interval Weight Loss.
When it comes to weight gain, hormones often fly under the radar as the real culprits. These tiny chemical messengers influence how your body stores fat, burns calories, and regulates appetite. In fact, research found that imbalances in hormones like cortisol, insulin, and thyroid hormones are linked to stubborn weight gain, especially around the abdomen. If you’ve been gaining weight unexpectedly or find it nearly impossible to shed those extra kilos despite maintaining a healthy lifestyle, your hormones might be to blame.
Let us explore the signs of hormonal weight gain, the key hormones involved, and how you can restore balance for a healthier, happier you.
Your body runs on a sophisticated network of hormones that quietly influence everything from how hungry you feel to where your body decides to store fat. If your hormones are out of balance, it can feel like your body is working against you. Some key hormones that play a big role in weight regulation are as follows:
Often thought of as the ‘muscle-building hormone,’ testosterone helps maintain muscle mass, which is essential for a healthy metabolism. Low testosterone levels, particularly in men, can lead to increased fat storage and reduced energy levels, making it harder to stay active and keep weight in check.
Estrogen levels naturally fluctuate throughout a person’s life, but imbalances—whether too high or too low—can contribute to weight gain. For example, low estrogen levels during menopause are linked to increased abdominal fat storage.
Cortisol is your body’s stress hormone. It can trigger fat storage when levels stay high for too long. Add insulin, your blood sugar regulator, into the mix, and things can spiral quickly. Insulin resistance, often caused by poor diet or chronic stress, leads to higher fat accumulation, especially around the belly.
Neuropeptide Y (NPY) is like your body’s ‘I’m starving!’ alarm. Released during fasting or stress, it increases appetite and encourages fat storage. High NPY levels can make resisting cravings feel almost impossible, leading to overeating and unwanted weight gain.
Hormonal weight gain doesn’t always announce itself clearly. Instead, it often sneaks in through changes that seem unrelated at first. Let us dive into the common indicators and what they mean for your health.
If your weight seems to shift dramatically without any changes in your diet or exercise routine, hormones could be at play. Fluctuations in cortisol levels, often due to chronic stress, can cause your body to retain water or store more fat. A study found that elevated cortisol levels are linked to higher abdominal fat.
Hormonal imbalances often dictate where your body stores fat. For example, low estrogen levels during menopause commonly lead to more fat around the abdomen, while high insulin levels can result in fat accumulation around the waist. This isn’t just about aesthetics—abdominal fat is linked to a higher risk of metabolic diseases.
Can’t stop thinking about chocolate or chips? Hormones like ghrelin (the hunger hormone) and leptin (the satiety hormone) might be out of sync. Research shows that chronic stress and poor sleep increase ghrelin, making you feel hungrier, while decreased leptin levels make it harder to feel full.
For women, irregular periods can be a key indicator of hormonal imbalances, especially related to estrogen or progesterone. Polycystic ovary syndrome (PCOS), which affects about 1 in 10 women, often causes irregular cycles and is linked to insulin resistance and weight gain.
Hormonal weight gain often comes hand-in-hand with feeling perpetually tired. Low thyroid hormone levels, a condition known as hypothyroidism, can slow down metabolism, leaving you feeling drained even after a full night’s sleep. Alarmingly, the American Thyroid Association estimates that nearly 60% of people with thyroid disorders are unaware of their condition and remain undiagnosed.
Feeling irritable or experiencing unexpected mood swings? Hormones like cortisol and serotonin, which regulate stress and mood, might be off balance. This can lead to emotional eating, further contributing to weight gain.
If you’ve been eating well, exercising regularly, and still can’t seem to shed kilos, your hormones might be working against you. Insulin resistance and low thyroid hormones are common culprits. They make it harder for your body to burn fat effectively.
Poor sleep isn’t just a symptom; it is also a cause of hormonal weight gain. Sleep deprivation disrupts hormones like cortisol, ghrelin, and leptin, increasing hunger and fat storage. According to research, adults who sleep fewer than six hours per night are more likely to have higher body fat percentages.
Hormonal weight gain isn’t just about what you eat or how much you exercise—it is often rooted in internal imbalances. Here is a look at the key causes behind hormonal weight changes:
Insulin Resistance: When your cells stop responding to insulin effectively, your body stores more fat.
High Cortisol Levels: Chronic stress leads to elevated cortisol, which promotes fat storage and increases cravings for sugary or fatty foods.
Low Thyroid Hormones (Hypothyroidism): An underactive thyroid slows your metabolism and makes weight gain nearly inevitable.
Polycystic Ovary Syndrome (PCOS): This common hormonal disorder disrupts insulin regulation, leading to weight gain, especially around the midsection.
Menopause-Related Hormonal Changes: Lower estrogen levels during menopause shift fat storage to the abdomen, even if your weight doesn’t change significantly.
Estrogen Dominance: Excess estrogen relative to progesterone can cause water retention and fat gain, particularly in the hips and thighs.
Low Testosterone in Men and Women: Reduced testosterone levels lead to muscle loss, a slower metabolism, and increased fat accumulation.
Growth Hormone Deficiency: Low growth hormone levels hinder fat metabolism and promote weight gain over time.
Medications Affecting Hormones: Certain medications, such as birth control pills or steroids, can alter your hormones and contribute to weight gain.
Adrenal Fatigue: Prolonged stress can overwork your adrenal glands, disrupting cortisol production and leading to weight issues.
Lack of Physical Activity: Hormones like insulin and cortisol thrive on regular movement, so a sedentary lifestyle can amplify imbalances.
Chronic Stress: Unrelenting stress disrupts the balance of multiple hormones, including cortisol, insulin, and ghrelin, thus fueling weight gain.
Hormonal weight gain goes beyond physical changes; it can have serious consequences for your overall health. When left unaddressed, it increases the risk of developing chronic conditions and takes a toll on your mental health. Recognising the risks helps highlight the importance of addressing hormonal imbalances early.
Increased Risk of Heart Disease
Higher Likelihood of Diabetes
Risk of Hypertension
Poor Mental Health and Self-Esteem
Long-term Metabolic Disorders
Addressing hormonal weight gain involves more than just adjusting your diet or exercise routine—it is about correcting the hormonal imbalances causing the issue. By identifying the root cause and using a combination of lifestyle changes, medical treatments, and dietary adjustments, you can regain control of your weight and overall well-being.
Eating a diet full of whole foods like vegetables, lean proteins, and healthy fats helps keep your hormones in balance and supports weight management. These foods provide the nutrients your body needs to function well.
Too much stress raises cortisol, which can lead to fat storage and hunger cravings. Reducing stress with activities like yoga, meditation, or deep breathing can help keep cortisol in check.
Exercise, especially strength training, boosts metabolism and balances hormones like insulin and cortisol. It also builds muscle, which helps burn more calories even at rest.
Sleep is crucial for hormone regulation. Poor sleep can throw off hormones that control hunger and stress. Aim for 7-9 hours of sleep each night to keep your hormones—and weight—in balance.
If you think hormones are affecting your weight, see a doctor. Blood tests can help identify issues like thyroid problems or PCOS, so you can get the right treatment.
Too much sugar and processed food can spike insulin and lead to weight gain. Cutting back on these foods helps keep blood sugar levels stable and reduces fat storage.
Supplements like vitamin D or omega-3 fatty acids can support hormonal balance. Always check with a doctor before taking any supplements to make sure they’re right for you.
Recognising the signs of hormonal weight gain is key to understanding what might be happening in your body. Sudden weight fluctuations, persistent hunger, and specific fat accumulation are just a few indicators that your hormones may be out of balance. If you notice these signs, it is important to take action, whether through lifestyle changes, medical advice, or both, to address the underlying causes. By staying aware of these symptoms, you can take proactive steps toward better weight management and overall health.
Dr Nick Fuller is the founder of Interval Weight Loss and is a leading obesity expert at the University of Sydney with a Ph.D. in Obesity Treatment. Dr Fuller is also the author of three best-selling books and his work been published in top ranked journals in the medical field, including JAMA, Lancet and American Journal of Clinical Nutrition.