“For people who are struggling to avoid weight loss, sometimes getting enough calories, protein, and other nutrients can only be accomplished with very concentrated sources of calories,” says Karen Collins, MS, RD, Nutrition Advisor to the American Institute for Cancer Research (AICR.) Good choices include dried fruits, fruit smoothies, and healthy fats such as avocados and nuts. Gaining weight? Limit calorie-dense, nutrient-poor foods. Large weight gain, more common with breast and prostate cancer, lead to poorer outcomes, says Collins. Need more details? Check out AICR’s Cancer Resource.