The Top Medical Problems That Cause Weight Gain That You Need to Be Aware Of

Posted on April 19, 2019 by Sally-Anne Turner

The first thing we look at when we gain weight unexpectedly is usually our diet, often blaming putting on the pounds on not eating right or exercising enough but sometimes, there are medical reasons for weight gain and there are some key conditions and diseases you need to be aware of. Understanding the underlying medical causes of weight gain is absolutely crucial because it can mean the difference between struggling with ineffective diet plans and actually addressing the root cause of your weight health challenges.

Weight gain that occurs despite your best efforts to maintain a healthy lifestyle can be incredibly frustrating and demoralising. You might be eating nutritious meals, exercising regularly, and making all the right choices, yet the number on the scales continues to climb. This type of unexplained weight gain is often a signal that something deeper is happening within your body—something that requires medical attention rather than just another diet plan.

At Bodyline Clinic, we've supported over 100,000 patients across the UK with their weight health journeys over the past 18 years, and we've seen firsthand how undiagnosed medical conditions can sabotage even the most dedicated weight loss efforts. Our experienced clinical team understands that effective weight management must address the whole person, including any underlying health conditions that might be contributing to weight gain. That's why we take a comprehensive approach to every patient's care, considering medical history, hormone levels, and overall health status before developing a personalised treatment plan.

If you appear to be gaining weight, despite eating well and exercising properly and aren't taking any medications that are known for causing weight gain, it may be worth speaking to a GP to establish whether any of these issues could be a concern. However, it's important to understand that even if you do have one of these medical conditions, weight loss is still possible with the right support and treatment approach. Many of the conditions we'll discuss can be managed effectively, and at Bodyline, we work alongside your existing healthcare providers to ensure you receive comprehensive care that addresses both your medical condition and your weight health goals.

The connection between certain medical conditions and weight gain is complex and multifaceted. These conditions don't just make you feel hungrier or less motivated to exercise—they actually change the fundamental way your body processes energy, stores fat, and regulates metabolism. Understanding these mechanisms is the first step towards taking control of your weight health, even when medical conditions are working against you.

Underactive Thyroid / Hypothyroidism

One of the most common conditions that causes weight gain is suffering from an underactive thyroid which is formally known as Hypothyroidism. This happens when your thyroid gland isn't producing enough thyroid hormones to regulate your metabolism, therefore your metabolism slows down and weight gains occur. The thyroid gland, a small butterfly-shaped organ located at the base of your neck, produces hormones that control virtually every aspect of your metabolism—how quickly you burn calories, how efficiently you convert food into energy, and how your body regulates temperature.

When thyroid hormone production drops below normal levels, it's like turning down the thermostat on your body's metabolic furnace. Everything slows down. Your heart rate may decrease, you might feel cold more easily, and your body becomes far less efficient at burning the calories you consume. This metabolic slowdown can lead to weight gain even when you're eating the same amount of food that previously maintained your weight. Many people with hypothyroidism describe feeling like they've suddenly hit a wall—no matter how little they eat or how much they exercise, the weight continues to accumulate.

The weight gain associated with hypothyroidism isn't typically dramatic—most people gain between 5 to 10 pounds, though this can vary considerably depending on the severity of the condition and how long it goes undiagnosed. However, this weight can be incredibly stubborn and resistant to traditional diet and exercise approaches because the underlying metabolic problem hasn't been addressed. It's not about willpower or dedication; it's about your body's fundamental ability to process energy being compromised.

An underactive thyroid is usually treated with hormone replacement therapy, meaning it is a condition that has to be managed daily, so if you are suffering with it, you need to get it diagnosed. The standard treatment involves taking levothyroxine, a synthetic version of the thyroid hormone T4, which your body converts into the active hormone T3. Once your thyroid hormone levels are restored to normal ranges, your metabolism should return to its previous state, making weight loss significantly easier to achieve.

Other symptoms of an underactive thyroid include tiredness, muscle aches and weakness, constipation, loss of libido and for women, changes in your menstrual cycle such as irregular and heavier periods. You might also experience dry skin, thinning hair, a puffy face, hoarseness in your voice, elevated cholesterol levels, and difficulty concentrating or remembering things—often described as "brain fog." Depression is also commonly associated with hypothyroidism, and the combination of physical symptoms and low mood can create a challenging cycle that affects every aspect of your life.

If you suspect you might have hypothyroidism, a simple blood test measuring your thyroid-stimulating hormone (TSH) levels can provide a diagnosis. At Bodyline Clinic, we offer comprehensive health checks for women and men that include thyroid function testing alongside a wide range of other biomarkers to give you a complete picture of your health. Early diagnosis and treatment of hypothyroidism can prevent further weight gain and make it much easier to achieve your weight health goals.

It's worth noting that even with thyroid hormone replacement, some people continue to struggle with their weight. This is where specialist support becomes invaluable. Our medical weight loss programmes at Bodyline can work alongside your thyroid treatment to provide additional support through safe, clinically supervised weight loss medications and personalised nutritional guidance tailored to your specific metabolic needs.

Polycystic Ovary Syndrome

A condition that causes weight gain in women is Polycystic Ovary Syndrome, often referred to as PCOS. A problem with the ovaries thought to be hormone related and associated with the production of too much insulin and too much testosterone, PCOS can cause weight gain due to this hormone imbalance. PCOS affects approximately one in ten women of childbearing age in the UK, making it one of the most common hormonal disorders affecting women, yet it remains widely misunderstood and frequently underdiagnosed.

The relationship between PCOS and weight gain is complex and bidirectional—PCOS can cause weight gain, but excess weight can also worsen PCOS symptoms, creating a frustrating cycle that can be difficult to break. The hormonal imbalances characteristic of PCOS, particularly insulin resistance, make it significantly harder for women to lose weight through diet and exercise alone. Insulin resistance means your body's cells don't respond properly to insulin, causing your pancreas to produce more and more of this hormone in an attempt to keep blood sugar levels stable. High insulin levels promote fat storage, particularly around the abdomen, and make it extremely difficult to access stored fat for energy.

Women with PCOS often describe feeling like their bodies are working against them. They might follow the same diet and exercise programme as a friend without PCOS and see dramatically different results. This isn't a failure of willpower or dedication—it's a reflection of the underlying metabolic dysfunction that characterises PCOS. The elevated testosterone levels associated with PCOS can also affect body composition, leading to increased fat storage in the abdominal area rather than the hips and thighs, creating an "apple-shaped" body type that's associated with higher health risks.

Other common symptoms of PCOS include excess hair growth, irregular periods and trouble getting pregnant. You might notice unwanted hair growth on your face, chest, or back (hirsutism), thinning hair on your scalp, acne that persists beyond your teenage years, and dark patches of skin, particularly in the creases of your neck, groin, and under your breasts. Many women with PCOS experience irregular or absent periods, and PCOS is one of the leading causes of infertility in women. The condition is also associated with an increased risk of developing type 2 diabetes, high blood pressure, and cardiovascular disease later in life.

Diagnosing PCOS typically involves a combination of symptom assessment, blood tests to measure hormone levels, and an ultrasound scan to look at your ovaries. However, it's important to understand that you don't need to have cysts on your ovaries to be diagnosed with PCOS—the name is somewhat misleading, and many women with the condition have normal-looking ovaries on ultrasound.

Managing PCOS and achieving weight loss with this condition requires a multifaceted approach. Lifestyle modifications, including a balanced diet that manages insulin levels and regular exercise, form the foundation of PCOS management. However, many women find they need additional support to achieve meaningful weight loss. At Bodyline, our women's health services include specialist support for women with PCOS, combining medical weight loss treatments with nutritional guidance specifically designed to address insulin resistance and hormonal imbalances.

Certain medications can also help manage PCOS symptoms and support weight loss. Metformin, a medication commonly used for type 2 diabetes, is often prescribed for PCOS to improve insulin sensitivity. Some women also benefit from hormonal contraceptives to regulate periods and reduce androgen levels. Our experienced clinical team at Bodyline can work alongside your existing healthcare providers to ensure your weight loss programme complements your PCOS treatment plan, giving you the best possible chance of success.

Cushing's Syndrome

A rare condition but one worth knowing about if you have been through steroid treatment or diagnosed with a tumour somewhere in the body, Cushing's Syndrome is caused by abnormally high levels of the hormone cortisol which leads to weight gain. Cortisol, often called the "stress hormone," plays vital roles in your body, including regulating blood pressure, reducing inflammation, controlling blood sugar levels, and helping you respond to stress. However, when cortisol levels remain persistently elevated, it can wreak havoc on your metabolism and body composition.

Cushing's Syndrome is most common in people who have gone through long-term steroid treatment or have a tumour. The weight is usually gained in the face, on the chest and in the stomach due to the hormone redistributing fat to these areas. This characteristic pattern of weight gain is one of the hallmarks of Cushing's Syndrome—patients often develop what's described as a "moon face" (rounded, full face), a "buffalo hump" (fat accumulation at the back of the neck), and increased abdominal fat, whilst their arms and legs may actually become thinner due to muscle wasting.

The most common cause of Cushing's Syndrome is long-term use of corticosteroid medications, such as prednisone, which are prescribed for conditions like asthma, rheumatoid arthritis, lupus, and other inflammatory conditions. These medications are incredibly effective at reducing inflammation, but prolonged use at high doses can lead to Cushing's Syndrome. Less commonly, the condition can be caused by the body producing too much cortisol on its own, usually due to a tumour in the pituitary gland, adrenal glands, or elsewhere in the body.

Beyond the characteristic weight gain pattern, Cushing's Syndrome causes a range of other symptoms that can significantly impact quality of life. These include purple or pink stretch marks on the abdomen, thighs, breasts, and arms; thin, fragile skin that bruises easily; slow healing of cuts and infections; severe fatigue and muscle weakness; high blood pressure; elevated blood sugar levels or diabetes; mood changes including depression, anxiety, and irritability; irregular or absent periods in women; and decreased sex drive. Men with Cushing's Syndrome may experience erectile dysfunction and reduced fertility.

If you're taking long-term steroid medications and experiencing unexplained weight gain with the characteristic distribution pattern, it's crucial to speak with your doctor. Never stop taking prescribed steroids suddenly, as this can be dangerous, but your doctor may be able to adjust your dose or switch you to a different medication. If Cushing's Syndrome is caused by your body producing too much cortisol, treatment will depend on the underlying cause and might include surgery, radiation therapy, or medications to reduce cortisol production.

Living with Cushing's Syndrome and trying to manage your weight can be extremely challenging. The high cortisol levels not only promote fat storage but also increase appetite and cravings, particularly for high-calorie foods. At Bodyline Clinic, we understand the unique challenges faced by patients with hormonal conditions like Cushing's Syndrome. Our personalised weight loss programmes can be adapted to work alongside your medical treatment, providing additional support and monitoring to help you achieve the best possible outcomes given your individual circumstances.

Insomnia/Trouble Sleeping

We've spoken before about how menopausal insomnia can cause weight gain but Insomnia or trouble sleeping at any stage of your life can be a contributing factor to why you're piling on the pounds. The relationship between sleep and weight is far more significant than most people realise, and chronic sleep deprivation can sabotage even the most dedicated weight loss efforts through multiple biological mechanisms.

Tiredness causes an imbalance between the hormone that says you're hungry and the one that says you're full, meaning you feel hungry more often and full less frequently, leading to you eating more than you actually want or need. Specifically, lack of sleep increases levels of ghrelin, the hormone that stimulates appetite, whilst simultaneously decreasing levels of leptin, the hormone that signals fullness and satisfaction. This hormonal disruption means you're fighting against your own biology when you're sleep-deprived—your body is literally telling you to eat more, even when you don't need additional calories.

Research has consistently shown that people who regularly sleep less than seven hours per night consume significantly more calories than those who get adequate sleep, often without even realising it. The difference can amount to several hundred extra calories per day, which adds up to substantial weight gain over time. When you're tired, your brain's reward centres also become more responsive to food, making high-calorie treats even more appealing than usual. This is why that chocolate bar or packet of crisps seems absolutely irresistible when you're exhausted.

We also tend to crave high sugar and high carbohydrate foods when we're tired to give us energy which should be enjoyed in moderation as part of a healthy balanced diet and if eaten to excess, they can cause us to gain weight. Your body is desperately seeking quick energy to compensate for the fatigue you're experiencing, and sugary, starchy foods provide the fastest glucose boost. Unfortunately, these foods also cause rapid spikes and crashes in blood sugar, leading to a cycle of cravings and energy fluctuations that makes it incredibly difficult to maintain healthy eating patterns.

Beyond the hormonal and appetite changes, sleep deprivation also affects your metabolism directly. When you don't get enough sleep, your body becomes less efficient at processing glucose, leading to higher blood sugar levels and increased insulin production. Over time, this can contribute to insulin resistance, which makes weight gain more likely and weight loss more difficult. Sleep deprivation also increases cortisol levels, and as we've discussed, elevated cortisol promotes fat storage, particularly around the abdomen.

There's also a practical element to consider—when you're exhausted, you're far less likely to exercise or prepare healthy meals. You might skip your morning workout because you're too tired, or order a takeaway for dinner because you don't have the energy to cook. You might also stay up later, giving yourself more hours in the day during which you might eat, and late-night eating is particularly problematic for weight management because your metabolism naturally slows down in the evening.

The causes of poor sleep are varied and can include stress, anxiety, depression, sleep disorders like sleep apnoea, chronic pain, hormonal changes (particularly during menopause), medications, and simply poor sleep hygiene. If you're struggling with persistent sleep problems, it's important to address the underlying cause rather than just accepting tiredness as a normal part of life. At Bodyline, our menopause treatment programmes include support for sleep disturbances, recognising that addressing sleep problems is crucial for successful weight management during this life stage.

Improving your sleep quality can have a dramatic impact on your weight loss efforts. Prioritising seven to nine hours of quality sleep per night, establishing a consistent sleep schedule, creating a relaxing bedtime routine, and optimising your sleep environment can all help. If you're doing everything right with your diet and exercise but still struggling to lose weight, poor sleep might be the missing piece of the puzzle.

Depression and Anxiety

Often forgotten as being medical conditions but mental health problems such as depression and anxiety have many physical effects on your body, including weight gain in some cases. The connection between mental health and physical health is profound and bidirectional—your mental state affects your physical health, and your physical health impacts your mental wellbeing. When it comes to weight, this relationship is particularly complex, with mental health conditions both contributing to weight gain and being exacerbated by it.

Although some people do lose weight when suffering from depression or anxiety, some people turn to food for comfort and support during these hard times which when combined with a lack of motivation to exercise that many people suffer with too, you can find yourself gaining weight. Depression, in particular, can make even basic self-care feel overwhelming. Planning and preparing healthy meals, getting to the gym, or even just going for a walk can feel like insurmountable tasks when you're struggling with low mood, fatigue, and lack of motivation.

The relationship between depression and weight gain involves multiple mechanisms. Depression affects the same brain chemicals that regulate appetite, particularly serotonin, which is why some people experience increased appetite and cravings for carbohydrate-rich foods when they're depressed. These foods temporarily boost serotonin levels, providing a brief mood lift, which can lead to a pattern of emotional eating where food becomes a primary coping mechanism for difficult emotions.

Depression is also associated with disrupted sleep patterns, and as we've discussed, poor sleep contributes to weight gain through hormonal changes and increased appetite. The fatigue that characterises depression makes physical activity feel even more exhausting, leading to a more sedentary lifestyle. Depression can also affect your metabolism directly, with some research suggesting that depression is associated with increased inflammation and metabolic changes that promote weight gain.

Anxiety, whilst sometimes associated with weight loss due to nervous energy and reduced appetite, can also lead to weight gain in many people. Stress and anxiety trigger the release of cortisol, and chronic elevation of this hormone promotes fat storage, particularly around the abdomen. Anxiety can also lead to emotional eating as a way of self-soothing, and many people find themselves reaching for food when they're feeling anxious, even when they're not physically hungry.

The impact of anxiety on eating patterns can be significant. Some people with anxiety disorders develop disordered eating patterns, including binge eating, where they consume large amounts of food in a short period, often feeling out of control during these episodes. Others might engage in mindless eating throughout the day as a way of managing anxious thoughts and feelings. The combination of stress-induced cortisol elevation and increased calorie intake creates a perfect storm for weight gain.

Don't forget that medications such as steroids and anti-depressants are also associated with weight gain, so if you have started on tablets such as those, your weight gain may be no more severe than the effects of those but if you are concerned you're suffering from other symptoms as well as weight gain and feel your diet doesn't explain this, always go and see your GP! Many commonly prescribed antidepressants, particularly selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants, can cause weight gain as a side effect. This can be incredibly frustrating—you're taking medication to improve your mental health, but the weight gain that results can actually worsen your mood and self-esteem.

The weight gain associated with antidepressants can occur through several mechanisms. Some medications increase appetite directly, whilst others may slow metabolism or cause fluid retention. Some antidepressants affect blood sugar regulation, leading to increased cravings for sweet foods. The amount of weight gained varies considerably between individuals and different medications, but it's not uncommon for people to gain 10 to 20 pounds or more whilst taking these medications.

If you're taking antidepressants and experiencing significant weight gain, it's important to discuss this with your doctor. Never stop taking prescribed mental health medications without medical supervision, as this can be dangerous. Your doctor may be able to switch you to a different medication with a lower risk of weight gain, or adjust your dose. Some newer antidepressants have a more neutral effect on weight, and in some cases, medications like bupropion may even support weight loss.

At Bodyline Clinic, we understand the complex relationship between mental health and weight management. Our experienced clinical team takes a compassionate, holistic approach to weight loss, recognising that mental health is an integral part of overall wellbeing. We work carefully with patients who are taking mental health medications, ensuring that any weight loss treatment we provide is safe and appropriate given their individual circumstances. Our specialised support programmes are designed for patients with complex medical histories, including mental health conditions, providing the additional clinical oversight needed to achieve safe, sustainable weight loss.

Managing weight whilst dealing with depression or anxiety requires addressing both the mental health condition and the weight concerns simultaneously. This might involve a combination of psychological support, medication management, lifestyle modifications, and in some cases, medical weight loss treatment. The key is to work with healthcare professionals who understand the intricate connections between mental and physical health and can provide comprehensive, coordinated care.

Taking Control of Your Weight Health

Understanding that medical conditions can contribute to weight gain is empowering because it means you can stop blaming yourself and start addressing the real underlying issues. Weight gain caused by medical conditions isn't about lack of willpower, laziness, or moral failing—it's about biological processes that are working against you. Once you identify and treat any underlying medical conditions, weight loss becomes significantly more achievable.

If you recognise yourself in any of the conditions we've discussed, the first step is to speak with your GP about getting properly diagnosed and treated. Blood tests, hormone panels, and other diagnostic tools can identify most of these conditions, and effective treatments are available for virtually all of them. At Bodyline, our comprehensive Explore Women's Health Check and Explore Men's Health Check services evaluate key biomarkers to provide you with an in-depth understanding of your health and wellbeing, potentially identifying issues that might be contributing to weight gain.

Even with appropriate treatment for underlying medical conditions, many people still need additional support to achieve their weight loss goals. This is where specialist weight management services become invaluable. At Bodyline Clinic, we've spent nearly two decades developing safe, effective, medically supervised weight loss programmes that work alongside treatment for underlying health conditions. Our medical weight loss programmes include a range of treatment options, from prescription appetite suppressants to the latest GLP-1 weight loss injections, all delivered within fully supported programmes that include nutritional guidance, lifestyle advice, and ongoing clinical monitoring.

Our experienced team of doctors and nurse prescribers understands that successful weight management for people with medical conditions requires a personalised approach. We take the time to understand your complete medical history, current medications, and individual circumstances before developing a treatment plan tailored specifically to your needs. We also work collaboratively with your existing healthcare providers to ensure coordinated care that addresses all aspects of your health.

With seven CQC-regulated clinics across the Northwest of England and convenient online consultation services available UK-wide, accessing specialist weight management support has never been easier. Whether you prefer face-to-face appointments at one of our Bodyline clinics in Birkenhead, Liverpool, Manchester, St Helens, Stockport, Stoke-on-Trent, or Warrington, or the convenience of remote video consultations from the comfort of your home, we're here to support you every step of your weight loss journey.

Book a free consultation at Bodyline Clinic to discuss how we can help you achieve your weight health goals, even when medical conditions are making it challenging. Our compassionate, experienced team is ready to provide the specialist support you need to finally break through the barriers that have been holding you back. Don't let undiagnosed or poorly managed medical conditions continue to sabotage your weight loss efforts—take control of your health today and discover what's possible with the right support and treatment.

Remember, achieving a healthy weight isn't just about appearance—it's about improving your overall health, reducing your risk of serious diseases, increasing your energy levels, and enhancing your quality of life. Whatever medical challenges you're facing, there is a path forward, and you don't have to walk it alone. Contact Bodyline Clinic today on 0800 995 6036 or visit our website to learn more about our comprehensive weight management services and take the first step towards a healthier, happier you.