Unexplained weight loss, or losing weight without trying — particularly if it's significant or persistent — may be a sign of an underlying medical disorder.
The point at which unexplained weight loss becomes a medical concern is not exact. But many doctors agree that a medical evaluation is called for if you lose more than 5 percent of your weight in six months to a year, especially if you're an older adult. For example, a 5 percent weight loss in someone who is 160 pounds (72 kilograms) is 8 pounds (3.6 kilograms). In someone who is 200 pounds (90 kilograms), it's 10 pounds (4.5 kilograms).
Your weight is affected by your calorie intake, activity level, overall health, age, nutrient absorption, and economic and social factors.
If you're losing weight without trying and you're concerned about it, consult your doctor — as a rule of thumb, losing more than 5 percent of your weight within six to 12 months may indicate a problem. If you're an older adult with many or more-serious underlying health issues, even a smaller amount of weight loss may be significant.
Your doctor will work with you to try to determine what's causing the weight loss. At first that will involve a thorough history, a physical examination and basic laboratory testing. Imaging scans to look for hidden cancers are not usually helpful unless some other clue points in that direction.
Sometimes, if the basic evaluation is negative, watchful waiting for one to six months is a reasonable next step. You may need a special diet to prevent further weight loss or to regain lost pounds.
Jan. 11, 2018
- AskMayoExpert. Abnormal weight loss. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2016.
- Evans AT, et al. Approach to the patient with unintentional weight loss. https://www.uptodate.com/contents/search. Accessed July 2, 2017.
- Abu Freha N. The yield of endoscopic investigation for unintentional weight loss. European Journal of Gastroenterology & Hepatology. 2017;29:602.
- Ferri FF. Weight loss, unintentional. In: Ferri's Clinical Advisor 2018. Philadelphia, Pa.: Elsevier; 2018. https://www.clinicalkey.com. Accessed July 2, 2017.
- AskMayoExpert. Crohn disease. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2017.
- Ritchie C, et al. Geriatric nutrition: Nutritional issues in older adults. https://www.uptodate.com/contents/search. Accessed July 2, 2017.
- Wilkinson JM (expert opinion). Mayo Clinic, Rochester, Minn. July 9, 2017.