Weight Loss & Constipation

While most people have a bowel movement every day, having a bowel movement every 2 to 3 days is not a concern if that pattern is comfortable and normal for you. Constipation means that you have difficulty moving your bowels or have a bowel movement less often than is usual for you. Constipation with weight loss can occur for a number of very different reasons. If you are trying to lose weight, the change in your diet can cause constipation. If you are losing weight without trying, you may have a potentially serious condition that needs prompt treatment.

Unexplained Weight Loss

If you are constipated and losing weight without trying, your doctor will ask when the weight loss started and how much you have lost. Losing a couple of pounds is probably not a matter of concern unless you are very underweight, but losing 5 percent or more of your usual weight over a period of 6 to 12 months might indicate a problem. For example, a 150-pound person who is constipated and unintentionally loses at least 7.5 pounds -- 5 percent -- in a year should seek medical attention.

Dietary Causes

If you are trying to lose weight, your constipation may be related to the changes in your diet. Adding high-fiber foods to your diet, including whole grains, salads, raw fruits and vegetables, may be enough to get your bowels moving again. Drinking more water can help, too, especially if you are exercising more than usual. If you are drinking enough, your urine will be pale yellow and plentiful. If you are dehydrated, it will be dark and scanty.

Potentially Serious Causes

A number of potentially serious conditions could cause constipation and unintentional weight loss, including eating disorders, irritable bowel syndrome with constipation, ulcerative colitis or bowel obstruction. The combination of constipation and weight loss can also be a sign of cancer of the colon and rectum, so it is important to let your doctor know what is happening, especially if you have a history of cancer in your family.

What to Tell Your Doctor

Your medical history can help your doctor determine the cause of your constipation and weight loss. Be prepared to discuss the amount of weight loss, starting date of the symptoms, diet history, fluid intake description of your stools and presence of other symptoms such as bloating or pain. Also report whether or not you feel better after having a bowel movement or if you have the sense that you have not completely emptied your bowels. Your doctor also needs to know if any of your family members have had cancer or other conditions affecting the bowels.


Notify your doctor if you unintentionally lose 5 percent or more of your normal weight, especially if you also have constipation. Seek immediate medical attention if you experience vomiting, bloody bowel movements, severe abdominal pain or a tight, obviously expanded belly in addition to the constipation and weight loss. These signs may indicate that you have a serious condition that needs prompt treatment. Furthermore, if you are elderly and your constipation began suddenly or has become worse, contact your doctor or go to the emergency room.

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