Creatine in Treating Patients With Cancer-Associated Weight Loss

DISEASE CHARACTERISTICS: * Histologically or cytologically confirmed cancer other than primary brain cancer * Considered incurable with available therapies * History of weight loss ≥ 5 lbs in 2 months or fewer AND/OR estimated intake of \< 20 cal/kg daily * Determination by attending physician that weight gain would benefit patient * Perception by patient that weight loss is a problem * No symptomatic or untreated brain metastases * No clinical evidence of ascites PATIENT CHARACTERISTICS: Age * 18 and over Performance status * ECOG 0-2 Life expectancy * At least 3 months Renal * Creatinine normal Cardiovascular * No poorly controlled congestive heart failure * No poorly controlled hypertension Other * Able to reliably receive oral medication * Must be alert and mentally competent * No known obstruction of the alimentary tract, malabsorption, or intractable vomiting * No diabetes that is controlled by insulin * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Chemotherapy * Concurrent chemotherapy allowed Endocrine therapy * No other concurrent adrenal corticosteroids, androgens, or progestational agents within 30 days after study entry * Concurrent short-term dexamethasone for chemotherapy-associated emesis is allowed * Concurrent inhalant, topical, or optical steroids allowed Radiotherapy * No concurrent radiotherapy to the bowel or stomach * Other concurrent radiotherapy allowed Other * No prior creatine use * No concurrent tube feedings or parenteral nutrition