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Weight Loss & Muscle Weakness

author image Milo Dakota
Since 2005, Milo Dakota has ghostwritten articles and book manuscripts for doctors, lawyers, psychologists, nutritionists, diet experts, fitness instructors, acupuncturists, chiropractors and others in the medical and health profession. Her work for others has appeared in the "Journal of the American Medical Society" and earned accolades in "The New York Times." She holds a Master of Art in journalism from the University of Michigan.
Weight Loss & Muscle Weakness
A thin woman is looking exhausted. Photo Credit: KatarzynaBialasiewicz/iStock/Getty Images

If you experience weight loss and muscle weakness, you could be suffering from a serious medical condition. But it may also be that your muscles are simply fatigued due to over-exertion, intentional rapid weight loss, poor nutrition or a virus. You may simply need to rest, eat or wait for a flu bug to pass. But if you have any concerns regarding your weight loss and muscle weakness, seek prompt treatment.

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Simple Causes

If you are eating fewer than 1000 calories a day or if your diet plan eliminates certain foods—no carbohydrates, for instance—your body may be reacting to the change. Fatigue, including muscle fatigue, is a common side effect of restricted diets, according to Joanne Larson, a registered dietitian. If you undertook a vigorous exercise program to facilitate weight loss—particularly if you hadn’t been active before dieting—your muscles may be reacting both to new exertion and loss of nutrients, according to Lt. Arthur S. Pemberton, of the Naval Medical Center in Portsmouth, Virginia. Weight loss and muscle fatigue can also accompany some viruses. Dehydration from exercise, illness or a dietary cleanse can cause fatigue.

Cause for Concern

Sudden, unintended weight loss and muscle weakness could signal potential disease, some serious, Lt. Pemberton says. If you are a woman and experience heavy periods, weakness could be a sign of anemia. If your blood is pink rather than deep red, iron deficiency could be your problem. If, in addition to weight loss and fatigue, you also suffer from anxiety, increased appetite, increased sweating, insomnia and double vision, you could have an overactive thyroid. You may need treatment for hyperthyroidism, Graves disease or Addison’s disease, Lt. Pemberton says.

General or Specific Weakness?

Some auto-immune diseases as well as depression, cardiopulmonary disease and cancer can give you an overall feeling of weakness. If your weakness is specific—you have trouble grabbing onto a ball or combing your hair—your problem could be neurological. Spinal cord lesions and some infections can cause neurological problems. Your health history and medical tests can help determine the cause of your muscle weakness.

Changes to Consider

If your urine is dark yellow, you may need to drink water. If it’s brown or red, ask yourself if you’ve recently ingested anything with red dye, such as burgundy wine. If the change in color is not related to something you ate or imbibed, it could indicate a problem with your kidney, bladder or prostate. If you have consumed undercooked pork, for example, your weakness could signal trichinosis.

Seek Answers to Questions

Don’t be overly alarmed or too complacent about weight loss and muscle weakness. If you can’t peg the symptoms to recent events in your life or they don’t clear up quickly, seek medical attention. The solution may be as simple as adding red meat to your diet or taking iron supplements if you’re vegetarian. And if the problem and its solution are more complex, early treatment is the wisest option.

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