8 reasons you are losing weight unexpectedly
Unexpected weight loss can feel alarming. One day, your favourite jeans are loose, and you’re standing on the bathroom scale wondering, “Where’s the rest of me gone?” If losing weight wasn’t part of your plan, it’s natural to be concerned about what might be causing it.
This blog covers the most common reasons for unexpected weight loss to help you understand what might be at play. While some causes can be minor, others might require medical attention. By the end, you’ll have a list of possible reasons and know when to consult a doctor. (Spoiler alert: if you’re unsure, it’s always better to check!)
Is Unexplained Weight Loss Normal?
First, let’s quickly address an obvious question. No, it’s not ‘normal’ to lose weight without trying. While our weight might fluctuate a little here and there due to changes in diet or exercise, losing a significant amount (about 5% of your body weight in 6-12 months) without a clear reason could signal something behind the scenes affecting your health.
A variety of physical, emotional, and lifestyle factors can cause unexpected weight loss. Some reasons are easily fixable, while others require professional intervention. Here are the most common culprits.
8 Common Reasons for Unexpected Weight Loss
Changes in Diet or Eating Habits
We get it. Life can get busy, and sometimes, you unknowingly eat less than you need. Or perhaps you’re unintentionally burning more calories than usual without adjusting your food intake.
Here are some examples that could cause weight to drop:
- Skipping meals due to busy schedules or stress.
- Reduced appetite, possibly from mild gastrointestinal discomfort or following an illness.
- Eating less calorie-dense foods without realising it (hello, endless salad lunches!).
- Unconscious dieting, like cutting sugar or fried foods, without actively thinking about it.
Noticing these patterns early can help prevent unnecessary weight loss. If this sounds like you, try tracking what you’re eating for a week to ensure you’re hitting your calorie and nutrient needs.
Stress or Anxiety
Stress has a sneaky way of messing with your body. For some, stress triggers mindless snacking. But for others, it can suppress appetite completely. Whether it’s work pressures, family worries, or financial concerns, ongoing stress or anxiety increases cortisol levels, which can disrupt your digestion and metabolism.
Symptoms to watch out for alongside weight loss:
- Difficulty concentrating
- Trouble sleeping
- Muscle tension or stomach issues
If stress or anxiety is on your radar, consider speaking with a mental health professional for coping strategies. Oh, and maybe cancel that extra Zoom meeting?
Overactive Thyroid (Hyperthyroidism)
Your thyroid gland plays a significant role in managing your metabolism. If you’re losing weight unexpectedly and feel ‘revved up,’ you might have an overactive thyroid (hyperthyroidism).
Other symptoms include:
- Feeling hot or sweaty all the time (even when it’s chilly)
- Increased heart rate or palpitations
- Enlarged thyroid gland (noticeable around your neck)
A doctor can confirm this through some simple blood tests. Fortunately, treatments like medication or lifestyle adjustments can manage it. Once it is under control the unexpected weight loss should stop.
Chronic Illnesses or Conditions
Several underlying conditions could result in unintentional weight loss. Below are some of the more common ones:
Diabetes
When your body struggles to regulate blood sugar levels, it might start burning fat or muscle for energy instead, causing weight loss. Frequent urination, incredible thirst, or feeling tired could be flags for diabetes.
Digestive Disorders
Conditions like Crohn’s disease, coeliac disease, or irritable bowel syndrome (IBS) can interfere with how your body absorbs nutrients, leading to unexpected weight loss. Add symptoms like abdominal pain or persistent diarrhoea, and it’s time to see a doctor.
Cancer
We’re not here to scare you, but unexpected weight loss can sometimes be an early sign of cancers like those affecting the digestive system, lungs, or blood. It’s typically accompanied by other markers like fatigue, lumps, or changes in appetite.
While the big “C” word is scary, most unexpected weight loss isn’t related to cancer. Still, it’s always better to be proactive about your health and get checked.
Depression and Mental Health Issues
Ever heard the phrase “heartache makes you lose your appetite”? It’s true for many people dealing with depression, grief, or other mental health struggles. Emotional struggles can greatly affect appetite and energy levels.
What to look out for:
- Feelings of sadness or hopelessness that linger for more than a few weeks
- Loss of interest in activities you used to enjoy
- Difficulty concentrating
If this resonates with you, reaching out for support could make a world of difference. Whether it’s a trusted friend or a professional counsellor, don’t hesitate to seek help.
Side Effects of Medications
Certain medications list unexpected weight loss as a possible side effect. Some common culprits:
- Antidepressants or anti-anxiety medications
- Chemotherapy drugs
- Medications for ADHD, like stimulants
- Certain diabetes medications
Check the insert that came with your medication if you suspect it’s behind your weight loss. Don’t stop taking anything without consulting your healthcare provider first, though.
Ageing or Muscle Loss (Sarcopenia)
Our bodies undergo a range of changes as we age, and involuntary weight loss is sometimes one of them. Older adults may face challenges such as reduced appetite, changes in taste, or medical conditions. Muscle loss, known as sarcopenia, can also make numbers on the scale drop because muscle is heavier than fat.
Weight loss in this demographic is often tied to reduced strength or mobility, so it’s essential to address it with a healthcare provider to ensure it’s not impacting daily life.
Undiagnosed Infections
Certain infections, whether bacterial, viral, or parasitic, can cause unexpected weight loss by throwing your immune system into overdrive or affecting gut function. Examples include:
- Tuberculosis
- Gastrointestinal infections (e.g., H. pylori)
- HIV or chronic viral infections
If you’ve been dealing with other symptoms like fever, night sweats, or prolonged digestive issues, it’s worth investigating whether an undiagnosed infection might be to blame.
When to See a Doctor
While this guide covers some possible reasons for unexpected weight loss, you should always trust your gut (pun intended). If you’ve lost more than 5% of your body weight in six months and don’t know why, consulting a healthcare provider is the best step. They’ll use your medical history and some tests to figure out what’s happening.
Here’s when you shouldn’t wait:
- Severe fatigue, ongoing weakness, or low energy
- Gastrointestinal issues like pain, bloating, or diarrhoea
- Persistent symptoms beyond a month
Take Action for Your Health
Unexpected weight loss can seem daunting, but there’s good news. Most causes are treatable once identified. Whether it’s adjusting your lifestyle, managing stress, or tackling a health condition, the first step is knowing what’s happening, which is where professionals come in.
And one last thing: try not to ignore your body’s signals. If something feels off, trust yourself. A healthier, happier you is worth the effort.
