What Causes Pain in the Lower Left Back?
19 June 2026
Experiencing loss of appetite and back pain at the same time does not necessarily mean something serious is wrong, but the combination deserves attention. Back pain is extremely common, while appetite can temporarily decrease because of pain, stress, illness, medication, or digestive problems.
Persistent appetite changes alongside unexplained back pain can sometimes occur with infections, kidney or urinary problems, digestive conditions, inflammatory disease, or more serious illness. The other symptoms you experience can help determine whether ordinary back-care measures are appropriate or whether medical assessment should come first.
Loss of appetite and back pain can have many possible explanations. Sometimes significant pain temporarily reduces the desire to eat. In other cases, both symptoms may result from another health problem.
Possible causes include:
Medical assessment becomes particularly important when these symptoms occur with unexplained weight loss, fever, night sweats, persistent abdominal or urinary symptoms, progressive pain, neurological changes, or feeling generally unwell.
They can be, although they do not necessarily have the same cause.
One possibility is that the back pain is mechanical while discomfort, poor sleep, stress, or medication temporarily affects appetite.
Another possibility is that an illness elsewhere in the body causes both symptoms. Certain kidney, urinary, digestive, inflammatory, and infectious conditions can produce pain around the back while also affecting appetite.
The symptoms could also be unrelated.
When trying to understand loss of appetite and back pain, consider:
These details can help a healthcare professional distinguish common mechanical back pain from a condition requiring further investigation.
Yes, particularly when the pain is significant.
A painful back episode can disrupt:
Some people also experience nausea when they are in considerable pain.
Medication can contribute as well. Certain medicines taken during a painful episode may cause digestive symptoms or affect appetite.
A mild appetite change that lasts for a short period during an acute episode is different from persistent or unexplained appetite loss.
If appetite remains noticeably reduced or you begin losing weight without trying, it is sensible to seek medical advice.
Back pain alone is extremely common and is usually not caused by a serious disease.
Appetite loss deserves additional attention because it is not a typical defining symptom of ordinary mechanical lower-back pain.
Certain accompanying symptoms increase the importance of professional assessment.
If you are eating less for an extended period, some weight loss may be expected.
However, weight that continues to decrease without intentional changes to your diet or activity can also occur with various health conditions.
Persistent unexplained weight loss alongside back pain should be investigated.
Back pain accompanied by fever, chills, or a significant feeling of illness may indicate infection or another medical problem.
Do not simply assume this pattern is caused by a strained muscle.
Mechanical back pain commonly changes with position, movement, and activity.
Pain that continues to worsen or remains severe regardless of position deserves assessment, particularly when other systemic symptoms are present.
Ordinary back pain can certainly disturb sleep.
However, persistent pain that is consistently worse at night or does not improve with rest can be one factor healthcare professionals consider when determining whether further investigation is appropriate.
Seek medical advice if back pain occurs alongside persistent abdominal pain, vomiting, significant nausea, unexplained bloating, unusual fullness, or major changes in bowel habits.
Pain around the back or flank accompanied by blood in the urine, painful urination, difficulty passing urine, fever, or significant changes in urinary frequency may point toward a kidney or urinary problem.
Seek urgent medical assessment if back pain occurs with:
These symptoms should not be managed solely with exercises or home back-pain treatments.
There is no single explanation for loss of appetite and back pain. Understanding the range of possibilities helps explain why persistent symptoms should not automatically be treated as an ordinary spinal problem.
One relatively straightforward explanation is mechanical back pain combined with a temporary change in appetite.
Mechanical back pain can develop after:
This type of pain commonly changes with movement or position.
For example, sitting, standing, walking, bending, or lifting may alter the symptoms.
If pain is significant, poor sleep, stress, and disruption to your normal routine may temporarily reduce your desire to eat.
Persistent appetite loss, however, should not automatically be blamed on a strained muscle or other mechanical problem.
Infections can cause systemic symptoms such as:
Depending on the infection, pain may also be experienced around the back.
Spinal infections are uncommon, but infection is one of the conditions healthcare professionals consider when back pain occurs with fever or systemic illness.
Kidney and urinary infections can also cause discomfort around the back or flank.
If you feel significantly ill rather than simply sore, seek medical advice.
The kidneys are positioned toward the back of the abdominal cavity, beneath the lower ribs.
Because of their location, kidney-related discomfort can sometimes be mistaken for musculoskeletal back pain.
Depending on the underlying condition, symptoms may include:
Kidney stones, kidney infections, and other urinary problems can produce different symptom patterns.
Back or flank pain accompanied by urinary or systemic symptoms deserves medical assessment.
Some problems originating in the abdomen can produce discomfort that is perceived around the back.
Digestive conditions can also directly affect appetite.
Additional symptoms might include:
The combination of digestive symptoms, loss of appetite and back pain makes it particularly important to consider whether the problem originates outside the spine.
Medication can sometimes contribute to appetite changes.
The following side effects could occur, depending on the medication:
This can be particularly relevant if symptoms began after starting a new medicine or changing the dosage.
Do not stop prescribed medication without appropriate advice. Speak with your doctor or pharmacist if you suspect medication is affecting your appetite.
Stress can influence appetite, sleep, muscular tension, and pain sensitivity.
Some people eat more during periods of stress, while others lose interest in food.
Stress can also make existing back discomfort feel more difficult to manage.
However, persistent physical symptoms should not automatically be attributed to stress. Physical and emotional factors can interact, while unexplained symptoms may still require medical assessment.
Certain inflammatory diseases can affect the spine and other areas of the body.
Depending on the condition, symptoms may include:
A healthcare professional can determine whether the symptom pattern warrants further investigation.
Cancer is not a common explanation for ordinary back pain, and experiencing loss of appetite and back pain does not mean you have cancer.
However, persistent appetite changes can be one of several systemic symptoms that deserve attention when they occur alongside unexplained or progressive pain.
Features that strengthen the case for medical assessment include:
These symptoms have many possible explanations other than cancer.
Their presence means the cause should be properly investigated rather than guessed.
Yes.
Not every pain felt in the back originates from the muscles, joints, discs, or nerves of the spine.
Internal organs can sometimes produce referred pain, where discomfort originating in one area is perceived somewhere else.
Kidney, urinary, digestive, and other abdominal conditions may occasionally produce pain around the back or flank.
One useful clue is whether symptoms behave mechanically.
Mechanical pain often changes with:
Pain originating elsewhere may behave differently, although this distinction is not reliable enough for self-diagnosis.
If back discomfort occurs with appetite changes, fever, abdominal symptoms, urinary problems, unexplained weight loss, or feeling generally ill, seek appropriate medical advice.
There is no single test required for everyone.
A healthcare professional will normally begin by asking about your symptoms and medical history.
They may ask:
A physical examination may assess the spine, abdomen, neurological function, or other areas depending on the symptoms.
Further investigation might include blood tests, urine tests, or imaging when clinically appropriate.
Not everyone with back pain needs an MRI or CT scan. Testing should be based on the overall clinical picture.
Once serious and non-musculoskeletal causes have been appropriately considered, treatment can focus on the back itself.
Mechanical lower-back pain is extremely common.
Depending on the individual, conservative management may involve:
This distinction is especially important with loss of appetite and back pain because a treatment designed for the spine will not address symptoms caused by an internal organ or systemic illness.
Spinal decompression is intended to provide controlled unloading or stretching through the spine.
Some people with mechanical lower-back stiffness find this comfortable as part of a broader routine involving movement, mobility, and strengthening.
However, decompression only makes sense when the symptoms are actually related to the musculoskeletal system.
It cannot treat:
This is why someone experiencing unexplained loss of appetite and back pain should not immediately assume that a spinal treatment addresses the underlying problem.
Once non-musculoskeletal causes have been appropriately excluded and the remaining back symptoms are mechanical, decompression may be considered as one part of conservative back care.
If you’re researching home options, our guide to the best spinal decompression device explains the different approaches and what to consider before choosing one.
The purpose of the Spinal Backrack is to facilitate controlled spinal decompression at home.
When appropriate for mechanical lower-back symptoms, it may complement:
It should not be used on the assumption that every pain felt around the back comes from the spine.
If the appetite problem has been explained or resolved and the remaining back symptoms are mechanical, you can then consider whether spinal decompression belongs in your broader management routine.
Whether exercise is appropriate depends on what is causing your symptoms.
If you have ordinary mechanical back pain and otherwise feel well, staying reasonably active is generally preferable to spending prolonged periods completely inactive.
If you are feverish, weak, unable to eat properly, experiencing significant abdominal symptoms, or generally unwell, starting an intensive exercise programme is not the priority.
Seek medical advice first.
For uncomplicated mechanical back pain, appropriate activities may include:
Walking provides regular movement without requiring special equipment.
Start with a duration that you can handle and work your way up.
Moving your spine through comfortable ranges can help maintain mobility.
There is no need to force painful positions.
Lie on your back with your knees bent.
Gently raise your hips while keeping the movement comfortable and controlled.
Lower slowly.
Begin on your hands and knees.
Slowly extend one leg behind you while maintaining comfortable trunk control.
If appropriate, progress by extending the opposite arm.
As symptoms improve, strengthening the trunk, hips, legs, and back can help rebuild physical capacity.
The longer-term objective is to return to normal activity rather than remain permanently dependent on very gentle exercises.
For uncomplicated mechanical back pain, prolonged bed rest is generally not the goal.
Some temporary reduction in activity may be sensible during a severe flare-up, but complete inactivity for long periods can reduce strength and physical capacity.
A more practical approach is relative rest.
This means temporarily reducing activities that significantly aggravate symptoms while continuing comfortable movement.
The situation changes if you feel systemically unwell.
When loss of appetite and back pain occur with fever, significant weakness, persistent vomiting, dehydration, or another acute illness, identifying and treating the underlying condition takes priority over a back-exercise routine.
When appetite is only mildly reduced during a short period of pain or stress, practical strategies may include:
These measures should not become a way of ignoring persistent appetite changes.
Speak with a healthcare professional if your appetite remains substantially reduced, eating becomes difficult, or your weight begins decreasing without intention.
Yes.
Weight naturally fluctuates, but losing weight consistently without intentionally changing your diet or activity can provide important clinical information.
Pay attention if:
You do not need to wait until weight loss becomes dramatic before seeking medical advice.
There is no universal number of days.
A temporary appetite change during an obvious short-term illness or painful episode may resolve as you recover.
Seek medical advice sooner if:
The more warning signs occurring together, the less appropriate it becomes to continue treating the problem as ordinary back pain.
Most back pain does not require emergency treatment.
Certain symptoms are exceptions.
If you experience back pain, get medical help right away.
Urgent assessment may also be appropriate for severe back or abdominal pain accompanied by serious illness, collapse, breathing difficulty, or rapidly worsening symptoms.
Loss of appetite and back pain can occur with significant pain, infection, kidney or urinary problems, digestive conditions, medication side effects, stress, inflammatory disease, and, less commonly, serious illnesses. Persistent symptoms or additional warning signs should be medically assessed.
Yes. Significant pain can temporarily affect appetite by interfering with sleep, activity, stress levels, mood, and normal routines. Persistent appetite loss should not automatically be attributed to back pain.
Appetite loss is not a typical defining symptom of mechanical lower-back pain. A temporary reduction may occur during a painful episode, but persistent appetite changes deserve further consideration.
Yes. Certain kidney and urinary conditions can cause flank or back pain alongside nausea, fever, urinary changes, feeling unwell, or reduced appetite.
Certain digestive and abdominal conditions can reduce appetite, while pain originating in the abdomen may sometimes be perceived around the back. Persistent digestive symptoms occurring alongside back pain should be assessed.
Stress can influence appetite, sleep, muscular tension, and pain sensitivity. However, persistent or unexplained symptoms should not automatically be attributed to stress without considering other possible causes.
No. These symptoms have many possible explanations, and ordinary back pain is very common. Persistent unexplained appetite loss, unintended weight loss, progressive pain, significant night pain, or a previous history of cancer are reasons to seek medical assessment, not proof that cancer is present.
Appetite loss is not a typical defining symptom of a lumbar disc herniation. Severe pain could indirectly affect someone’s desire to eat, but persistent appetite changes should not automatically be attributed to a disc problem.
Do not assume spinal decompression is appropriate while the cause of unexplained appetite changes remains unclear. A spinal decompression device is intended for mechanical spinal symptoms and cannot treat internal-organ or systemic disease.
No. The Spinal Backrack is designed to support gentle spinal decompression. It does not treat appetite changes or medical conditions responsible for them.
If the back pain is mechanical and you otherwise feel well, gentle activity may be appropriate. If you feel ill, feverish, weak, unable to eat normally, or do not understand why your appetite has changed, seek medical advice before starting a new exercise programme.
Experiencing loss of appetite and back pain can understandably cause concern, but there are many possible explanations.
Sometimes significant mechanical pain temporarily interferes with sleep, activity, stress levels, and normal eating habits. In other cases, appetite changes provide an important clue that the problem may not originate solely from muscles, joints, discs, or other spinal structures.
Persistent appetite loss, unexplained weight loss, fever, feeling generally unwell, progressive pain, significant night symptoms, or abdominal and urinary problems should therefore prompt medical assessment.
Once serious or non-musculoskeletal causes have been appropriately excluded and the remaining back symptoms are mechanical, an active approach involving regular movement, progressive strengthening, mobility work, and appropriate conservative treatment can become the focus.
For suitable mechanical lower-back stiffness, the Spinal Backrack may complement that routine by supporting gentle spinal decompression at home. The priority, however, is identifying the cause before attempting to treat an unexplained back problem.
Sign up our newsletter to get article update about backrack therapy.
Unsure which protocol you need? Select your symptoms for a clinical recommendation.