Insulin resistance & Weight Management – by Freda Coetzee – May 16, 2025

9 causes of sudden weight gain

Solve the mystery – find out why you gained weight unexpectedly Losing weight is not easy and when you suddenly put on extra kilograms it can be baffling. Kilograms that feel like they’ve come out of nowhere can leave you disheartened. If you can pinpoint why you’ve gained weight, you can tackle the problem head-on. There are many reasons why you might experience sudden weight gain – here are 9 common causes of unexpected weight gain. You have hypothyroidism One of the first things to check, when you inexplicably gain weight, is your thyroid. According to the American Thyroid Association, one in eight women develop a thyroid disorder in her lifetime. When your thyroid is underactive you will have hypothyroidism. Your metabolism might slow down which can lead to weight gain. Other symptoms include fatigue, dry skin, hair loss, muscle cramps, or constipation. What to do: If you have hypothyroidism symptoms, ask your doctor to check your thyroid by doing a blood test. You are stressed and tired Anxiety affects your hormones. When you’re stressed out, your body releases more of the hormones ghrelin and cortisol which will increase your appetite and get you craving carbs. Stress also suppresses the hormone, leptin. This hormone helps you feel full after you’ve eaten but when the amount of leptin drops because of stress, you can eat copious amounts of food without feeling satisfied. Being tired and not sleeping well will also raise your ghrelin levels and lower your leptin levels – resulting in you eating lots of food without feeling full. What to do: Find ways to manage your stress levels that work for you. Many people testify that yoga, meditation and breathing techniques help them live a calmer life. Exercising will also help lower your stress levels and might also help you sleep better. There are many other things you can do to get better sleep like limiting screen time before bedtime and getting more exposure to bright light during the day. You are dehydrated Not drinking enough water can cause bloating. Doctors also believe that we can mistake the feeling of thirst for the feeling of hunger. Instead of drinking fluids when we are thirsty, we might eat more food. What to do: Health experts often recommend people drink eight 8-ounce glasses of water per day. You can add slices of lemon or cucumber to your water, for flavour. You quit smoking So, you stopped smoking cigarettes – well done! Smoking leads to lots of health complications. The downside of quitting is an increase in appetite as smoking can suppress cravings. The problem is once you’ve quit smoking, the food cravings can hit you hard and if you give in, you will put on extra weight. What to do: Do activities like meditation or exercise that help release feel-good endorphins and that will provide a good distraction. You have high insulin levels The hormone, insulin works like a delivery truck. It transports glucose (your body’s main source of energy) out of the bloodstream and into cells. If you are overweight, you do not respond to insulin well and your pancreas needs to pump more and more of this hormone into your bloodstream. These high insulin levels keep the body in storage mode and make weight loss more difficult. This is the beginning of becoming insulin resistant and if left unchecked can lead to the development of Type 2 diabetes. The bottom line – if your insulin levels are high, your body will make it more difficult to lose weight. What to do: There are many lifestyle changes, like eating low GI foods and exercising that will help lower your blood glucose levels and in turn, help your pancreas to not overproduce insulin. You can keep track of your blood glucose levels with a monitor. If your blood glucose levels are continuously high, talk to your doctor. You have bacterial overgrowth in your gut The human gut is one of the most densely populated bacterial communities on earth. There are bacteria that is beneficial to your health, but some can have harmful effects. You will always have good and bad gut bugs but if the harmful bugs grow exponentially, you can develop small intestinal bacterial overgrowth (SIBO). SIBO is associated with bloating, abdominal pain, diarrhoea, and sudden weight gain. What to do: If you suspect that you might have SIBO, talk to your doctor about treatment. To treat SIBO your doctor may prescribe antibiotics. You can also change your diet. You want to include food that helps good bacteria flourish and exclude foods that bad bacteria like. Eat a variety of high-fibre fruits and vegetables. You want to eat less high-processed, sugar-rich foods. Most people believe that a Mediterranean diet is best to promote good gut health. You are taking certain medications Copious prescription and over-the-counter medication can trigger weight gain. Antidepressants can affect the appetite centre in your brain and can cause you to eat more. Furthermore, beta-blockers (used in blood pressure medication) can slow down your metabolism. Allergy medication can also cause weight gain. A Yale University study found a direct link between taking antihistamines consistently and obesity. It seems that antihistamines like Benadryl, can disrupt an enzyme in the brain that helps regulate food consumption. What to do: Talk to your doctor about the side effects of your medication. You are going through perimenopause Perimenopause is the transition period before menopause and usually starts in your 40s, but it can start a little earlier. During this time your: estrogen  levels will rise and fall unevenly which can lead to weight gain. During your 40s your body will also undergo other changes like loss of muscle mass. These changes coupled with perimenopause can cause you to gain weight quickly. What to do: Talk to your doctor about ways to manage your weight as you get older. It will also benefit you greatly if you can build up your calorie-burning muscle. Keep up cardio three times a week for 30 minutes but add challenging weight training on top of that. You have polycystic ovary syndrome Polycystic ovary syndrome (PCOS) is very common as one in five women develop this disorder. It is an endocrine disorder that throws off the balance of reproductive hormones, estrogen, and testosterone. Symptoms include irregular periods, facial hair growth, and migraines. What to do: If you are overweight you can drastically improve your symptoms and risk of developing long-term PCOS health problems by losing weight. Talk to your doctor about different treatment options for PCOS. Takeaway Don’t lose heart if you have suddenly gained a few kilograms – there are many reasons for sudden weight gain. If you know why you have suddenly put on extra kilos, you can tackle the problem head-on. Remember to make your weight loss journey fun. Having and maintaining a healthy weight should not feel like a struggle.