During cancer treatment, appetite often fades and even the smell of food can feel overwhelming, so there are many days when you simply cannot eat as much as before. If you are losing weight even when eating the same amount, it may not just be because you are 'eating less' — your body may be burning more energy than usual. The combined loss of weight and muscle during treatment is called cachexia, and because it can affect your recovery and your ability to tolerate treatment, it is worth taking seriously rather than brushing aside.
A helpful idea here is 'energy density.' The goal is to choose foods that pack more calories and protein into each spoonful. The less appetite you have, the more practical it is to aim for 'small but rich' meals rather than forcing yourself to eat large amounts.
Cold, soft foods can be surprisingly helpful. Cold dairy such as ice cream, yogurt, and pudding has a milder aroma that triggers less nausea, and it tends to be easier to swallow when the mouth is sore. Adding a little ground nuts, milk or soy milk, cheese, egg, or mashed tofu keeps the texture soft while raising both calories and protein.
If eating a lot at once is hard, it can help to let go of the 'three meals a day' framework and instead eat small amounts every 2 to 3 hours. Also, drinking a lot of water right before a meal can fill you up quickly so that you cannot eat the food itself — it is often better to spread fluids out between meals.
That said, the same diet does not suit everyone. If you have diabetes, difficulty swallowing, or significant diarrhea or constipation, the precautions differ. If you lose more than about 5% of your body weight in a month, or if you can barely eat for several days, talk with your care team or a clinical dietitian, who can help with oral nutrition supplements or meal adjustments.
This article is for general information only and does not replace individual medical care. Please discuss your symptoms and any changes in eating with your own healthcare team.