Medical conditions that prevent weight loss

Medical conditions that prevent weight loss: 8 causes explained

These eight causes come up most often in the consulting room when someone isn't losing weight despite a good diet and enough exercise.

1. An underactive thyroid. Your metabolism slows, you gain weight and you get tired and cold more quickly.
2. Insulin resistance. Your body responds less well to insulin, your blood sugar fluctuates and burning fat becomes harder.
3. PCOS. A hormonal condition in women that often goes together with insulin resistance and stubborn excess weight.
4. Menopause. Falling oestrogen changes where you store fat and how much muscle mass you keep.
5. Medication. Antidepressants, antipsychotics, corticosteroids, anti-epileptics, beta blockers and some diabetes medicines can add weight.
6. Chronic stress. Persistently raised cortisol increases your appetite and directs fat towards your belly.
7. Lack of sleep and sleep apnoea. Too little or too restless sleep disrupts the hormones that regulate hunger and fullness.
8. Rarer conditions. Cushing's syndrome and problems with the pituitary gland are uncommon, but you can only rule them out with tests.

The first six often occur in combination. It is precisely that stacking that makes weight loss so hard.

Hormones out of balance: thyroid, insulin and PCOS

Hormones determine how fast you burn energy, how hungry you are and where you store fat. When they get out of balance, the maths of weight loss changes without you doing anything differently. That is the core of the complaint "I can't lose weight because of my hormones": your behaviour has stayed the same, your biology hasn't.

An underactive thyroid

Your thyroid drives your metabolism. If it works too slowly, your body gets less energy out of food and you gain weight, even with a normal eating pattern. For an underactive thyroid, Thuisarts.nl (the Dutch GP association's patient website) literally lists "you gain weight" as a symptom, along with tiredness, feeling cold and difficulty passing stools. The diagnosis isn't made on feel: blood tests show whether you have too little free T4 and too much TSH in your blood. Treatment usually consists of levothyroxine, a thyroid hormone in tablet form.

Insulin resistance and your blood sugar

With insulin resistance your cells respond less well to insulin, so your pancreas has to produce more and more of it. A high insulin level maintains fat storage and makes burning fat harder. You often recognise it by swings in your blood sugar: energy shortly after eating, then a dip, cravings for something sweet and a tired feeling.

Satiety matters at least as much as calories here. Your gut produces hormones that tell your brain you've had enough, including GLP-1. If that system works less well, the feeling of hunger stays switched on while your body has had enough.

PCOS

With PCOS, insulin and the female hormones work together against you. The condition often goes together with insulin resistance, so weight loss is slower than in women without PCOS. The Dutch PCOS guideline advises weight loss of 5 to 10% within six months for people with overweight, because that already measurably improves what is going wrong: insulin resistance, hormone levels and the cycle. That is a medical goal, not an aesthetic one, and it shows that a modest drop is already worthwhile.

Not losing weight during menopause: this is what happens

During menopause your oestrogen falls, and that changes where your body stores fat. Fat moves from hips and legs to your belly, while your muscle mass decreases and your resting metabolism drops. Many women do exactly the same as ten years earlier and still see the centimetres increase.

That feeling matches what research shows. A review article in the journal Climacteric concludes that the hormonal changes around menopause contribute substantially to more belly fat, with physical and psychological consequences. If you want to read further, the research on weight gain around menopause is summarised on PubMed.

In practice, this means that during menopause you need different levers than just eating less: strength training to preserve muscle mass, enough protein, and attention to sleep and stress. Our guide to weight loss during menopause sets out, symptom by symptom, what does and doesn't help.

Medicines that slow weight loss

Medicines are one of the most underestimated medical causes of not being able to lose weight. They increase your appetite, slow your metabolism or make you retain fluid. The weight gain often starts within a few months of starting, precisely in the period when your mind is on something other than your weight.

This classification follows the overview from Apotheek.nl (the Dutch pharmacists' patient information website) on weight gain from medication use. One rule is more important than all the others: never stop a medicine on your own. Discuss it with your doctor or pharmacist. There is often an alternative within the same group with less effect on your weight, and sometimes the medicine simply outweighs the kilos.

Stress, sleep and psychological factors

Chronic stress affects your weight through cortisol. That hormone keeps you alert, increases your appetite and directs fat storage towards your belly. As long as the stress stays, that brake stays on. That's how the situation arises that many people describe as "I can't lose weight because of stress": you do everything right and nothing happens.

Sleep reinforces that effect. Too little or too restless sleep disrupts the hormones that regulate hunger and fullness, so during the day you crave fast carbohydrates more. Sleep apnoea is a double trap here: excess weight increases the chance of it, and the poor sleep then makes losing weight harder.

Psychological factors count too. Comfort eating, depression, binge eating disorder or years of yo-yo dieting leave traces in your eating behaviour and in your hormones. "Not being able to lose weight for psychological reasons" is not a character flaw; it is a treatable factor that belongs in a medical programme.

Not losing weight? It's not a lack of discipline

With excess weight, your body actively defends the weight it is used to. When you lose weight, your satiety system speaks more quietly and your hunger system more loudly, and your metabolism drops a little more than you would expect from your new weight. That is biology, not weakness.

That's exactly why "I can't lose weight, I have no discipline" is almost always the wrong diagnosis. People who come to us usually have years of diets, exercise and personal training behind them. What was missing was not effort, but someone who worked out which medical brake was involved.

Tried everything and still not losing weight? At Qlinic, your own BIG-registered doctor (the BIG register is the Dutch register of healthcare professionals) personally looks at what is going on for you. See if it's right for you →

When should you involve a doctor?

See a doctor if your weight can't be explained by what you eat and how much you move. A consultation is certainly worthwhile if you have one or more of these signs:

• You have gained weight without your eating pattern or activity changing
• You're not losing weight despite at least three months of consistently eating less and moving more
• Alongside weight gain you have symptoms such as extreme tiredness, feeling cold, hair loss, dry skin or constipation
• You started new medication and gained weight afterwards
• Your cycle is irregular, you have excess hair growth or you have been diagnosed with PCOS
• You're going through menopause and notice the increase mainly around your belly
• You snore heavily, sleep restlessly or are constantly sleepy during the day
• Your BMI is 30 or higher; calculate your BMI if you don't know it

What the doctor does is not complicated. A conversation about your symptoms and the medicines you use, targeted blood tests including thyroid values and blood sugar, and a plan based on that. If a condition turns out to be involved, that is treated first. If there is no condition and you still can't lose weight, medically supervised weight loss is an option. What your GP (huisarts) can and can't prescribe for this, you can read in our article can my GP prescribe weight loss injections.

Medically supervised weight loss: how does it work?

Medical weight loss means a doctor treats your weight like any other medical complaint: with tests, a diagnosis, a treatment plan and monitoring. At Qlinic that starts with a consultation and intake with your own BIG-registered doctor, who personally assesses whether a programme suits you and what needs to be looked into first.

If a programme suits you, the doctor prescribes the treatment and the medication is delivered to your home. The medication in question is usually a GLP-1 treatment, with active substances such as semaglutide, tirzepatide or liraglutide, known under brand names such as Ozempic, Mounjaro and Saxenda. These medicines mimic the satiety hormone GLP-1 and above all take away the feeling of hunger, so that eating less is no longer a daily battle.

They are not without side effects: nausea, constipation, diarrhoea and abdominal pain occur, especially in the build-up phase. That's why in the Netherlands they are only available on prescription and a doctor is always involved. Never buy this medication online without a prescription; you then don't know what you're taking and there is no one keeping an eye on things if something goes wrong.

After that you see your own doctor every four weeks for follow-up. They check your progress, adjust the dose and are your point of contact if you experience side effects. Most people notice the first effect after about four weeks. You discuss pausing or stopping together with your doctor. So far we have helped around 50 people this way; on Google we have a 5.0 rating from more than 20 reviews.

We work with one fixed BIG-registered doctor: no changing care providers, but one doctor who knows your file.

Want to know whether medical weight loss suits you? Within a few minutes you'll know whether a programme with your own doctor, medication delivered to your home and a check-up every four weeks is possible for you. See if it's right for you →

Frequently asked questions about medical conditions that prevent weight loss

Is there an illness that stops you losing weight? Yes. An underactive thyroid, insulin resistance, PCOS, Cushing's syndrome and conditions of the pituitary gland can slow weight loss. They rarely explain everything, but they do demonstrably make weight loss harder. Only blood tests give a definitive answer.

What can be the reasons you're not losing weight? The most common reasons are hormonal (thyroid, insulin resistance, menopause, PCOS), medication-related (antidepressants, corticosteroids, antipsychotics, beta blockers) and lifestyle-related (chronic stress, lack of sleep, eating more than you think). Often several play a part at the same time.

Which medical conditions stop you losing weight? Hypothyroidism, insulin resistance and type 2 diabetes, PCOS, Cushing's syndrome, sleep apnoea and depression are the conditions most often behind stubborn excess weight. Pituitary problems can also play a role, although they are rare.

Which illness causes weight gain? An underactive thyroid is the best known, because your metabolism slows down. Cushing's syndrome causes weight gain around the belly, neck and face because of an excess of cortisol. PCOS and untreated sleep apnoea also often go together with weight gain.

Can I test myself for a medical cause? No, an online test can't demonstrate or rule out a medical cause. You can, however, list your symptoms and the medicines you use and calculate your BMI. That information makes the conversation with the doctor a lot more focused; the blood tests do the rest.

Does medical weight loss also help if no condition is found? Yes. If tests show no underlying condition and you still consistently can't lose weight, a medically supervised programme can offer a solution. A doctor then assesses whether treatment with medication suits your situation and supports you in it.