This research will examine the effectiveness of a guaraná nutrition energy bar supplement on cancer-related fatigue based on scores from fatigue questionnaires. Participants will be randomized to one of three study arms: 1) two guaraná energy bars/day, 2) one guaraná energy bar/day 3) usual-care only/ no guaraná energy bars during study in cancer patients who have completed cancer treatment. We would also like to find out if this energy bar supplement improves physical performance, mood and reduces plasma glutamine and inflammation.

Inclusion Criteria:

• Have a confirmed diagnosis of a malignant solid tumor between 4 and 36 months post-treatment (pathology report or MD documentation).
• Completed all forms of standard treatment (surgery, chemotherapy, radiation therapy, and/or immunotherapy) between 4 and 36 months prior to enrollment in the study.
• Be 18 years of age or older.
• Have cancer-related fatigue, as indicated by a response of a 4 or greater when asked to rate their level of fatigue at its worst in the past week on an 11-point scale anchored by "0": = 'no fatigue' and "10" = 'as bad as you can imagine' as taken from a single item question on the Symptom Inventory Questionnaire.
• Be able to read English (since the assessment materials are in printed format).

Exclusion Criteria:

• Participants must not: Have used guaraná supplements within the previous two months.
• Self-report that they are very sensitive to caffeine.
• Uncontrolled hypertension
• Have an allergy to walnuts, seaweed, soybeans and/or chocolate.
• Use medications for which caffeine intake is contraindicated including: β-adrenergic agonists, and/or medications that contain pseudoephedrine.

The information is not yet available to determine whether IPD should be made available to other researchers or not.