It sounds like your mother could be suffering from IBS (Irritable Bowel Syndrome). Weight loss is often a symptom of this—as is an intolerance to milk and spicy foods.
How To Gain Weight With IBS (Or A Sensitive Stomach)
If your mother's got a sensitive stomach or food intolerances, she'll want to avoid the foods that cause her discomfort. This can make gaining weight a bit more difficult than usual, but it's still accomplishable. Here are some things for your mom to try:
- Protein powder or shakes (lactose- and fat-free if possible)
- Carbohydrates like bread, pasta and potatoes
- Eating smaller, high-calorie meals—it's easier for people with sensitive stomachs to digest smaller portions than it is larger ones
- Adding nuts, seeds and fruit to cereal
- Using yogurt instead of milk where possible (obviously not in coffee!)