Weight Gain - Is it my pituitary? - Pituitary Foundation

Prefer to watch rather than read? At the bottom of this page, you can access a recording of a talk on this topic delivered by Prof Pinkney.

Introduction

Conditions affecting the pituitary gland, and other endocrine glands, give rise to a notoriously wide range of symptoms. People ask endocrinologists all sorts of questions. Many concerns relate to impaired energy, stamina, and everyday quality-of-life. Over the years, one of the commonest concerns I have heard is about weight gain. I’m asked whether this has resulted from the underlying endocrine condition or perhaps the medicines that I have prescribed!

The majority of diseases affecting the pituitary gland have some impact on weight, such as Cushing’s disease and the hormone deficiency states of hypopituitarism. However, weight gain from pituitary disease is usually relatively modest. However, one group of conditions that stand out as causing more substantial weight gain are those that affect the hypothalamus. These can be primary diseases of the pituitary, or other disorders of the hypothalamus such as tumours. The hypothalamus is an area of the brain that plays an important role in the control of appetite and body weight, and when disturbed through disease processes, substantial weight gain is a relatively common result.

Unfortunately, in a world where two thirds of people are overweight, and over one quarter are obese anyway, it is not surprising that many people with pituitary conditions are overweight or obese, not primarily as a result of the pituitary condition, rather for all the many other common reasons that we gain weight. Some people are more predisposed from a young age, as a result of their genes, but also the behaviours and habits that have been learned from parents, or that arise in the home environment. Gradual weight gain often results when the diet is out of balance, often with excessive food portions, sometimes poor food choices, and frequently as a result of eating when not hungry, as in situations of stress, emotion or boredom. Having said this, most people find it very difficult to control body weight in a world where many of us are relatively inactive, and highly processed foods are major components in most people’s diets.

Weight control – what are the options?

Whenever I am asked for help with weight loss, it is important to understand the likely causes. I first consider the possible contribution to weight gain of the underlying endocrine disease, any associated abnormalities of hormone levels, and whether adjustment of endocrine treatment is necessary. Sometimes this is the case, although with weight gain in most endocrine disease being relatively modest, it is always necessary to consider the many other common factors that usually lead to weight gain in everyday life. At our centre we also run a large weight management service for people with more severe obesity, and it turns out that endocrine factors as causes of severe obesity are relatively rare. Whereas it is all of the other common factors related to day-to-day dietary behaviour and physical activity that are usually the more significant factors. These factors always have to be considered, even if there has been an endocrine contribution to weight gain.

A variety of different treatments can be used to bring about weight loss. For people who are overweight, or at lower levels of obesity, it is usually possible to achieve significant weight loss through relatively simple modifications of day-to-day lifestyle. Undoubtedly, this requires commitment, and to maintain long-term changes, but this is the traditional cornerstone of weight management, and without commitment to this principle treatments are often ineffective. Another approach, that can be combined with behavioural and lifestyle change, is drug treatment. For many years the available drug treatments for weight loss were not particularly effective, but now there is a new generation of drugs that are significantly more effective and offer the possibility of more substantial weight loss. Not surprisingly, there is now huge interest in these new treatments.

New drugs – new treatment options for weight loss?

The two new medicines available for weight loss are Wegovy (Semaglutide) and Mounjaro (Tirzepatide). Availability of Wegovy was limited throughout 2024 due to supply problems, and it was not widely available in the NHS. Mounjaro has been reviewed by NICE and it is expected soon to be available for use in the NHS. Perhaps the main question about these medicines is whether and how they can help people to achieve and maintain long-term weight loss, because the clinical trials have shown that most weight is usually re-gained within one year of stopping treatment. If this happens in clinical practice, this would be demoralising, probably not a good use of money, and repeated cycles of weight loss and regain may also be harmful for health. The NHS will be expected to follow NICE guidance on the use of these drugs, both in terms of who is eligible for treatment, and the need to stop treatment in people for whom it is proving ineffective and not achieving weight loss.

How can I try drug treatment for weight loss?

This would require advice from your GP or endocrinologist. Currently, access to treatment varies, and in many areas remains limited. At present the NHS use of Wegovy is restricted to those with more severe obesity (body mass index of greater than 35), accompanied by one or more weight-related common health problems. Although endocrine diseases often cause some degree of weight gain, the question will be therefore whether that weight gain has caused other health problems such as diabetes or high blood pressure. Accordingly, you would need to have a medical assessment of eligibility for treatment. Currently this drug is only to be prescribed from specialist weight management clinics and for a maximum period of 2 years. Mounjaro will also begin to become available in 2025, also for those with above BMI 35, with other weight related health problems. It seems likely that Mounjaro will prove somewhat more effective than Wegovy for weight loss, although that is not to say that Wegovy is necessarily an inferior choice for many people, depending on the amount of weight loss that is sought. Mounjaro can already be prescribed by GPs as a treatment for diabetes, and NICE will be recommending that GPs will also be able to prescribe this drug for weight loss, without any limit on duration.

Why is access to drug treatment currently limited?

A major challenge for the NHS is that the demand for these new drugs is so high that it is neither possible for the country to afford the cost of the drugs if they are to be given to everybody who is eligible, nor does the NHS have sufficient staff and capacity to see, assess and monitor the treatment of so many people. This is a global challenge, and not just one for the UK. Accordingly, in the NHS it is going to be recommended that treatments are made available with the gradual rollout over the next few years. It is envisaged that the first group of people to be eligible will be those with serious and urgent weight-related health problems, such as needing urgent treatment for life-threatening conditions, such as heart surgery or a kidney transplant. After this initial rollout, which is expected to take about three years, a larger group of people with BMI over 35 and significant weight-related health issues such as diabetes, high blood pressure, and the range of other conditions, will become eligible for treatment. What this means is that most people with endocrine diseases, whether or not these have contributed to weight gain, are not likely to be eligible for treatment in the near future. The main exceptions are likely to be for people who also have other serious weight-related health problems. Therefore, potential eligibility for treatment would be considered by GPs in the first instance. It is also worth appreciating that many GPs currently have little capacity to begin assessing and treating obesity, but it is hoped that this will change in the years ahead with more investment in these services. There is also some variation around the country in eligibility and availability of drug treatment. Most areas of the UK currently have relatively little availability, although it is hoped that this inequality will begin to improve.

Should I purchase drug treatment privately?

The drugs can be purchased privately, and there are a range of commercial weight management services that are able to assess obesity and where appropriate start treatment. Over the past two years this has been the main way that people have been able to access these drugs, and this remains one good option. Clearly the full costs of treatment have to be borne, and for many people this is not necessarily straightforward, although on the other hand many people make the choice to prioritise weight loss over some of their other expenditure. If treatment is purchased privately, as with NHS treatment, a key issue for consideration is what happens after treatment stops, and whether it will be possible to maintain dietary and lifestyle changes that will perpetuate the weight loss that has been achieved.

What side effects can be expected?

There is no reason to expect that patients with pituitary diseases will be any more at risk of side effects. Most common effects of this class of drug are gastrointestinal, such as nausea, vomiting, tummy pain, diarrhoea and constipation. These affect many people in the early stages of treatment, but usually subside. However. they can persist for some people and lead to stopping treatment. The main potentially serious side effect that has received a lot of discussion is pancreatitis, and while there is still some uncertainty about the cause of this, it is currently considered that this is usually caused by gallstones resulting from weight loss, rather than the drug itself. All in all, this family of drugs look to be relatively safe and well tolerated, and appears to represent a significant step forward in weight loss treatment.

Key points

Whether or not you are eligible and suitable for drug treatment requires a medical assessment. This is especially the case for people with pituitary disease, who have more complex medical histories and treatment needs. An endocrinologist may confirm your eligibility and suitability but at present might not be able to prescribe the treatment for you. This may vary locally

If you are thinking of accessing drug treatment privately, remember that the prescribing doctor will not have access to your medical records. People with pituitary diseases usually have complex medical histories, hormonal disturbances, and are often taking many different treatments. For this reason, it is best to discuss this first with your NHS doctors rather than going straight to a private provider

Drug treatment is not necessarily the best option for all people. Some may be better off considering other treatments such as bariatric surgery. In order to assess the available options and to choose between them it is usually necessary to be referred to a specialist weight management clinic

If drug treatment for weight loss is commenced, it should be used in conjunction with a programme of dietary change and increased physical activity, aiming to bring about and maintain long-term lifestyle changes. Drug treatment alone is not a quick fix. Without commitment, most people experience gradual weight regain after treatment is stopped. The long-term effects of treatment are not currently well understood, or whether long-term treatment is necessary in order to avoid weight regain

Professor Jonathon Pinkney recently delivered an online talk discussing weight management and options for treatment. The recording of this talk is available below.

YouTube