Loss of interest in eating can come from many different medications, whether they directly suppress your appetite or create changes in your sense of smell and/or taste. It can also occur when medicines are causing nausea that makes the very thought of eating impossible (see "Nausea and Vomiting"). Although discontinuing the offending drug will usually quickly solve the problem, this is often not a possibility, so other approaches are needed.
First, consider the causes other than medications that might also be contributing to appetite loss:
To help make up for inadequate intake of micronutrients (vitamins and minerals), a high-potency multiple vitamin/mineral can be taken. Liquid multivitamins will decrease the number of pills you have to regularly swallow.
When the appetite's still not there, you may have to change your eating habits or patterns. Try to eat on a schedule and substitute multiple smaller snacks for three big meals. Even if you don't feel hunger pangs by the next scheduled intake, just sit down and do the best you can to eat as much as possible. Chow down on healthful snacks whenever you have the urge. Make the most of those times you do feel hungry and make every bite count. Anything that helps spark your interest in food should be tried, such as:
When sitting down to a whole meal seems impossible, supplemental drinks can be an excellent source of additional calories. Drinking a meal may seem a lot easier than eating one. Try a blended soup or a high-calorie blender drink, such as the following:
Combine regular milk (if there's no problem with lactose intolerance) or rice milk (such as Rice Dream) with half a banana, half an apple and a tablespoon of Knudsen Coconut/Pineapple Nectar (for the medium-chain triglycerides, or MCTs, and, of course, the piña colada taste). Instead of or in addition to the coconut milk as the source of MCTs, you can add a lot of calories with a tablespoon or two of coconut cream or oil or MCT oil, available in most health food stores. You can also add other fruits (fresh or frozen) and vanilla or other flavorings to this blender drink; just avoid anything with concentrated sugar. If you prefer the iciness of a smoothie, add ice when you blend this drink.
If you're not reaching the desired level of daily protein intake with the foods you're eating, it may also be useful to add high-quality protein powder to the blender drink. Among the best of the available protein powders are the whey protein products. In addition to weight gain, whey protein may contribute to increasing the antioxidant glutathione (GSH) in the body, an important additional benefit, as PHAs tend to have less-than-normal levels of glutathione. Another possible benefit is that some of the whey protein products are rich in immunoglobulins, the proteins that act as antibodies and may actually help in the body's defense against some infections. Don't overdo it when you use protein powders. Remember that too much protein can actually strain the kidneys. Large amounts of such protein powders can also cause diarrhea because they are water-seeking. A moderate amount to increase the protein content of your diet if you're not otherwise getting enough is reasonable.
If you don't want to create your own supplement, it may be helpful to use supplemental drinks made from powdered or liquid formulas that are low in sugar and fat (or that use predominantly MCTs), moderately high in good-quality protein and high in calories overall.
And, finally, some substances can act as appetite boosters, such as the following: