Question: My father is suffering from IBS and is loosing weight day by day.sometimes he even faints due to weakness.He cannot digest food .please help us and suggest us upon this problem.

Reference:
 Irritable bowel syndrome - aftercare IBS Mucus colitis IBS-D IBS-C Summary Irritable bowel syndrome (IBS) is a disorder that leads to abdominal pain and bowel changes. Your health care provider will talk about things you can do at home to manage your condition. What to Expect at Home Irritable bowel syndrome (IBS) may be a lifelong condition. You may be suffering from cramping and loose stools, diarrhea, constipation, or some combination of these symptoms. For some people, IBS symptoms may interfere with work, travel, and attending social events. But taking medicines and making lifestyle changes can help you manage your symptoms. Diet Changes in your diet may be helpful. However, IBS varies from person to person. So the same changes may not work for everyone. Keep track of your symptoms and the foods you are eating. This will help you look for a pattern of foods that may make your symptoms worse. Avoid foods that cause symptoms. These may include fatty or fried foods, dairy products, caffeine, sodas, alcohol, chocolate, and grains such as wheat, rye, and barley. Eat 4 to 5 smaller meals a day, rather than 3 larger ones. Increase the fiber in your diet to relieve symptoms of constipation. Fiber is found in whole grain breads and cereals, beans, fruits, and vegetables. Since fiber may cause gas, it is best to add these foods to your diet slowly. Medicines No one drug will work for everyone. Medicines your provider may have you try include: Antispasmodic medicines that you take before eating to control colon muscle spasms and abdominal cramping Antidiarrheal medicines such as loperamide Laxatives, such as lubiprostone, bisacodyl , and other ones bought without a prescription Antidepressants to help relieve pain or discomfort Rifaximin, an antibiotic that is not absorbed from your intestines It is very important to follow your provider's instructions when using medicines for IBS. Taking different medicines or not taking medicines the way you have been advised can lead to more problems. Stress Stress may cause your intestines to be more sensitive and contract more. Many things can cause stress, including: Not being able to do activities because of your pain Changes or problems at work or at home A busy schedule Spending too much time alone Having other medical problems A first step toward reducing your stress is to figure out what makes you feel stressed. Look at the things in your life that cause you the most worry. Keep a diary of the experiences and thoughts that seem to be related to your anxiety and see if you can make changes to these situations. Reach out to other people. Find someone you trust (such as a friend, family member, neighbor, or clergy member) who will listen to you. Often, just talking to someone helps relieve anxiety and stress. When to Call the Doctor Call your provider if: You develop a fever You have gastrointestinal bleeding You have bad pain that does not go away You lose over 5 to 10 pounds (2 to 4.5 kilograms) when you are not trying to lose weight Review Date 4/24/2017 Updated by: Michael M. Phillips, MD, Clinical Professor of Medicine, The George Washington University School of Medicine, Washington, DC. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team. 

Answer: Look for foods that make the symptoms worse and change your diet to avoid such foods. These may include  fatty or fried foods, dairy products, caffeine, sodas, alcohol, chocolate, and grains such as wheat, rye, and barley. Eat 4 or five smaller meals a day and follow your doctor's instructions to take medicines.