If you cannot figure out why you are gaining weight or can no longer shed pounds easily like you used to — despite your best efforts to eat right, exercise and take your vitamins every morning — you might be walking around with a hormone imbalance that has you hardwired to put on pounds.
Even when we think we’re being healthy, hormonal triggers to unwanted weight gain are too often neglected or overlooked. Testing can help you find the answer. But in the meantime, let’s look at the eight big culprits behind unwanted weight gain.
For women experiencing unexplained weight gain, our Female Weight Management Profile Test measures the key hormones linked to fat storage and metabolism — including cortisol, estradiol, testosterone, progesterone, DHEA and thyroid markers — in a single at-home kit.
8 Hormonal Causes of Unexplained Weight Gain
1. You Have an Estrogen to Progesterone Imbalance
Many women — especially those of childbearing age — have an estrogen dominance problem. If you exercise strenuously, you could be making less progesterone and estrogen is dominating, leading to weight gain in the hips, thighs and bottom. Other causes of estrogen dominance include disrupted ovulation (meaning no progesterone is produced), supplementing with estrogen alone without its balancing partner progesterone, and environmental factors such as pesticides, plastics, industrial waste products, car exhaust, meat, soaps and chemicals in furniture and carpets.
Diet — most importantly making sure you eat hormone-free — environmental avoidance of xenoestrogens, and targeted supplements can bolster your natural progesterone production and decrease estrogen dominance. Check out the Environmental Working Group for the full revelations and actions you can take.
2. You’re Not Getting Enough Vitamin D
Possibly due to our awareness of skin cancer and the use of sunscreen, our levels of vitamin D are lower than they were decades ago. Vitamin D, synthesised by the action of sunlight upon the skin, is converted to a vital hormone in our bodies. Deficiency has been linked to allergies including food allergies, asthma, weight gain, fatigue, diabetes and even cancer.
Our Vitamin D Test (D2, D3 and Total) measures your complete vitamin D status from a simple finger-prick at home — if testing uncovers a deficiency, supplemental vitamin D is cheap and readily available.
3. You Have High Cortisol Levels
High levels of cortisol — our stress hormone — are another big reason we tend to store fat and keep weight on, particularly in the abdominal area (that dreaded muffin top), until the stressor is minimised or resolved. High cortisol is associated with increased appetite, cravings for sugar and weight gain, belly fat in particular. You need to unwind every day with whatever shuts off your hyper-vigilance — even if it’s for just 10 minutes per day.
4. You’re Eating Processed “Healthy”
Excess salt and sugar are often hidden ingredients that are both inflammatory and causes of excess weight gain. Just because it’s at a health food store and it’s “gluten free” or “low fat” or “natural” does NOT mean it’s good for you. Packaging with the words “natural” and “healthy” can be very persuasive — and misleading.
5. You’re Eating Too Much Fat
Paleo and other higher-fat diets work for some people, but it is easy to get too many calories with foods that are high in fat. Fat is a nutrient and our bodies need some essential fatty acids — especially the “good fats” found in nuts, seeds, avocado and olive oil — but be careful not to go overboard if you want to lose weight.
6. You’re Skimping on Quality Sleep
Your hormones need sleep. The two hormones that are key in the relationship between sleep and weight loss are ghrelin and leptin. Ghrelin is the “hunger hormone” that tells you when to eat, and leptin its counterpart, the “satiety hormone”, tells you when to stop. When you’re sleep-deprived (defined as 7 hours or less a night), you have more ghrelin and thus more appetite. At the same time you have less leptin, so you never get the signal that you are full.
These key appetite hormones operate on the sleep-wake cycle, so anything that disrupts that cycle — such as high night-time cortisol — can upset the balance, leading to overeating and cravings. Our Sleep Hormone Test (UDH I) measures melatonin (MT6s) alongside cortisol and cortisone across the day from a simple at-home dried urine collection — revealing the hormonal imbalances that may be disrupting your sleep and driving weight gain.
7. You’re Not Eating Your Cruciferous Vegetables
Cruciferous vegetables — Brussels sprouts, kale, cauliflower, bok choy, broccoli and similar greens — are not only good for you because of the feeling of fullness from the fibre, but they’re also good for estrogen metabolism through a compound called indole-3-carbinol (I3C). It is a natural source of DIM (3,3-Diindolylmethane) that helps promote estrogen balance and helps clear the body of the toxic xenoestrogens we pick up from the environment. This is one of the cheapest, easiest ways to get your hormones and your weight in balance.
8. You’re Not Strength Training or Getting Enough Exercise
Moderate exercise lowers stress hormones, which in turn reduces the body’s tendency to store fat and increases calorie burning. Stretching exercises like yoga and Pilates also help to release tension in the body. Additional strength training or weight-bearing exercise (2–3 workouts a week) builds muscle, increasing anabolic hormones like testosterone and DHEA that rev metabolism.
The Bottom Line
Eating right, exercising and getting enough sleep are essentials that help keep hormones in balance, weight under control and belly fat at bay. But if you’re doing all of this and still struggling, consider testing to identify existing imbalances that could be thwarting your best efforts. It is simple, pain-free and convenient — and the results could reveal hidden imbalances and provide helpful information about what to do next.
Originally by Candace Burch, ZRT Laboratory. Reproduced with permission. Last reviewed: May 2026.