Mood and Mental Health While on Weight Loss Treatment
Some weight loss medications can affect mood. The advice is to tell your doctor or nurse practitioner about new or worsening depression or any unusual change in mood or behaviour (healthdirect).
This is general information, not medical advice. Experiences and outcomes vary between individuals, and the doctor or nurse practitioner who manages your treatment, or your GP, can look at your situation with you.
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Key Points
Mood changes, including depression, are a possible side effect of some weight loss medications.
A smaller appetite can take the enjoyment out of eating, and for some people it may lead to an eating disorder.
Before you start, tell your practitioner about any depression, anxiety or eating disorder, now or in the past, and every medicine you take.
The watch list below covers low mood, loss of interest, anxiety, sleep changes, worry about food and out-of-character behaviour. Tell a health professional if you notice any of them.
Weight loss medication is used alongside a healthy diet and regular physical activity, not instead of them.
How Weight Loss Medication Can Affect Mood
Some weight loss medications change how certain brain chemicals work to reduce appetite. That can affect your mood and may increase your risk of depression, so the advice is to speak to your doctor or nurse practitioner if you notice new or worsening symptoms of depression (healthdirect). Depending on the medication, the listed side effects also include insomnia, restlessness, anxiety and depression (Australian Obesity Management Algorithm).
Appetite matters too. As appetite falls, you may no longer enjoy eating, which can affect social situations, and for some people it may lead to an eating disorder. A December 2025 review for Australian health professionals noted that one group of these medications often interferes with the pleasure of eating, and it advises practitioners to discuss and monitor mental health during treatment.
Weight and Mood Are Linked
Weight and mood can affect each other. Obesity increases the risk of mental health problems such as depression and anxiety, and living with mental illness can affect your appetite and your motivation to be active, or to shop for and cook healthy food (healthdirect). For more on eating and mood, read about how sleep, stress and low mood can affect eating and what to check when weight loss stalls.
Weight itself can be a sensitive topic. Poor body image, low self-esteem, psychological problems and eating disorders such as binge eating are common in people living with obesity, and even being weighed can be upsetting for some people (Australian Obesity Management Algorithm).
Some health conditions linked with weight also affect mood. An underactive thyroid can cause low mood or depression, and polycystic ovary syndrome (PCOS) can bring mood changes such as depression, anxiety or mood swings. For more, read about weight and thyroid conditions and weight loss treatment with PCOS.
Before You Start: What to Tell Your Practitioner
Tell the doctor or nurse practitioner who assesses you about:
any depression, anxiety or other mental health condition, now or in the past
any eating disorder, now or in the past, including binge eating, purging or night eating
every medicine you take, including antidepressants
how you feel about food, your weight and being weighed
These answers matter. Depending on the medication, the reasons not to use it include anorexia nervosa or bulimia and the use of some antidepressant medicines, and the Australian Obesity Management Algorithm suggests practitioners ask about disordered eating and screen for depression with a questionnaire.
At Burst Health, a doctor or nurse practitioner calls you to discuss your situation, review whether treatment is clinically appropriate, explain any options and potential side effects, and answer your questions. For the full process, see how medical weight loss programs work.
The Mood Watch List
Look out for these changes while you are on treatment:
New or worsening low mood: feeling sad, teary, hopeless or worthless.
Loss of interest: no longer enjoying things you usually enjoy, or staying in instead of going out.
Anxiety or irritability: feeling anxious, restless, irritable or angry. Males are more likely to describe feeling tired, irritable or angry than feeling low or sad.
Sleep changes: trouble sleeping, or feeling tired during the day.
Worry about food or weight: skipping meals or fasting, counting kilojoules or calories obsessively, weighing yourself often, or feeling anxious or guilty about eating.
Out-of-character behaviour: any unusual change in how you act or feel.
Six changes to look out for during weight loss treatment.
Writing down what you notice, and when it started, can make it easier to explain to a doctor, nurse practitioner or mental health professional.
Who to Tell, and When
If you notice any change on the watch list, tell the doctor or nurse practitioner who manages your treatment, or your GP. If a side effect is troubling you, there may be ways to reduce it or other medicines that suit you better, so it is worth raising. You can also report a suspected side effect to the TGA.
For support, use the services below.
| What you need | Who to contact |
|---|---|
| Advice on low mood, anxiety or a mood change | Your doctor, nurse practitioner or GP |
| Depression or anxiety support | Beyond Blue 1300 22 4636 (24/7) |
| Support with eating or body image worries | Butterfly 1800 33 4673 (8am to midnight, 7 days) |
| Health advice from a nurse | Healthdirect 1800 022 222 (24/7) |
Butterfly's hours are in Australian Eastern time.
Eating Enough and Staying Active
Weight loss medication is used together with healthy lifestyle changes, not instead of them. With a smaller appetite you may not feel as hungry, so it is important to eat enough food and nutrients each day, as part of a balanced, healthy diet. A doctor, nurse practitioner or dietitian can check that you are getting what your body needs. For practical steps, read a realistic guide to losing weight.
Australia's physical activity guidelines recommend moderate to vigorous physical activity for 30 minutes or more on most days and muscle-strengthening activities on 2 or more days a week. The same guidelines recommend 7 to 9 hours of good quality sleep, with consistent bed and wake-up times. For ideas on moving more, see how many steps a day can support weight loss. A counsellor, dietitian or exercise physiologist can help with these changes.
For anyone considering treatment, Burst Health provides medical weight loss plans online, reviewed by an Australian-registered doctor or nurse practitioner who asks about your mental health before and during the plan: check whether you are eligible.
Frequently Asked Questions
Does weight loss medication affect mental health?
Yes, it can for some people. Depending on the medication, the listed side effects include depression, anxiety, restlessness and trouble sleeping. If you notice new or worsening depression or any unusual change in mood or behaviour, tell your doctor or nurse practitioner, or your GP. Experiences vary between individuals.
Can losing weight affect your mood?
Possibly. Weight loss can be associated with a range of potential mental health complications. Obesity also increases the risk of depression and anxiety, and poor body image and low self-esteem are common in people living with obesity. Even being weighed can be upsetting for some people. If your mood changes while you lose weight, talk to your GP or practitioner.
Can you take weight loss medication with antidepressants?
Sometimes, depending on the medication. Some weight loss medications should not be used with certain antidepressant medicines. Tell the doctor or nurse practitioner about every medicine you take, including antidepressants, before you start, so they can check how your medicines fit together. A pharmacist can also answer questions about your medicines.
How can you manage your weight with depression or anxiety?
A GP is a good first step. A GP can assess your mental health and refer you to a mental health professional. Living with mental illness can affect your appetite and your motivation to be active, or to shop for and cook healthy food. With a diagnosis of depression or anxiety, a mental health treatment plan lets you claim Medicare rebates for a set number of sessions each year.
Who should you tell about low mood on weight loss medication in Australia?
Tell the doctor or nurse practitioner who manages your treatment, or your GP, about any new or worsening low mood, anxiety or unusual change in behaviour. For support at any hour, call Beyond Blue on 1300 22 4636, and for eating or body image worries, call Butterfly on 1800 33 4673.
Medical weight loss plans, online
In three steps.
- 1Answer a quick questionnaireOnline, no appointment, no in-person visit.
- 2A practitioner reviews itAn Australian-registered doctor or nurse practitioner decides whether treatment is suitable for you.
- 3Start your planIf treatment is suitable, you start your plan with the practitioner supporting you throughout.
References
This article is general information only. Speak with a registered Australian healthcare practitioner about your own situation.