How To Gain Weight During or After Breast Cancer Treatment
After breast cancer surgery and other treatment, seeing the number on the scale go down is common. But weight loss can cause fatigue, poor recovery, a weakened immune system, and other health concerns, especially when your body is working hard to heal and recover.
Why do some breast cancer treatments cause weight loss?
Surgery to remove breast cancer, like a mastectomy or lumpectomy, takes a toll on your body. In fact, metabolism speeds up after physical trauma (like surgery), helping your body to heal by breaking down fat and muscle tissue more quickly.
If you’re taking narcotic analgesics (opioids) for pain, you might have nausea or appetite changes, which can make it harder to eat.
Chemotherapy can also cause weight loss. Common side effects of chemotherapy include fatigue, nausea, vomiting, and diarrhea — all of which can make it difficult to eat or for your body to absorb calories and nutrients.
Immunotherapy and targeted therapy may also cause side effects that affect your metabolism, appetite, or energy levels — all of which can lead to weight loss.
If you’ve lost weight but did not have any of these treatments, you’re not alone. All of our bodies are unique and respond to physical trauma and medications differently, so it’s possible to lose weight on any breast cancer treatment.
Regardless of your treatment regimen, talk to your doctor if you’ve lost weight. Together, you can determine a healthy weight for you to work toward. They may also refer you to a registered oncology dietitian. Many cancer centers have these nutrition professionals on staff.
Tips for maintaining or gaining weight during treatment
Even if you’re not losing weight during treatment, your calorie needs are higher than usual because your body is working hard to heal healthy tissue damaged by treatment.
But treatment side effects can make it hard to eat as much as your body needs. Use these tips to get more calories and nutrients in each day:
Try to eat small meals or snacks every 1–2 hours. Keep nutrient- and calorie-dense foods on hand, such as string cheese, nuts, crackers with nut butter, hard-boiled eggs, energy bars, or individual packages of pudding or custard.
Eat large portions when you do feel hungry.
Add starchy fruits, vegetables, and legumes. Starchy vegetables and fruits include potatoes, corn, bananas, plantains, cherries, mangoes, and jackfruit. Starchy legumes include peas, beans, and lentils. A bonus of eating these starchy plants? Getting more fiber. Dietary fiber enhances nutrient absorption, helps maintain regular bowel movements, and reduces the risk of multiple chronic diseases.
Include as many calories and nutrients as you can in the foods you can tolerate. Smoothies are a great option. They’re easy on the digestive system, making them a good choice if you’re dealing with appetite loss or nausea, vomiting, and/or diarrhea. And if you have taste changes or mouth and throat sores, they can be made to have a neutral flavor and even help soothe sores.
Tips for gaining weight after treatment
If your appetite returns, it may be easier to eat larger portions. But if you’re not getting enough calories to get to a healthy weight, it can help to make your meals more calorie-dense. Try these tips:
Add healthy fats — like avocado, nuts, seeds, and olive oil — to meals and snacks. Fats are calorie-dense, and also help your body absorb essential nutrients called fat-soluble vitamins.
Incorporate smoothies to pack a nutrient and energy punch — using fresh or frozen fruit as a base, you can add:
a handful of greens
some fibrous seeds or nuts, like chia seeds or almonds
oats or dates for extra carbohydrates
protein powder, Greek yogurt, cottage cheese, or even silken tofu
frozen or fresh veggies that don’t affect the flavor of the smoothie, like cauliflower
avocado, nut butter, or coconut oil to get healthy fats and make the smoothie creamier
fruit juice, milk, or a non-dairy milk alternative
Drink other liquid calories, like meal replacement shakes, milk, and fruit juice, can help boost your calorie intake without causing you to feel uncomfortably full.
Include a source of protein with every meal to support muscle growth — when you lose weight from breast cancer treatment, you’re not just losing body fat.
Top yogurt, oatmeal, or cereal with dried fruit, nuts, seeds, and nut butters for a tasty calorie booster.
Treat yourself to fun foods like ice cream or pizza. Your body needs the calories.
High-calorie foods for people in treatment for cancer
If eating larger portions is difficult or makes you feel uncomfortably full, there are many foods you can incorporate that pack high calories into small portions. Examples include:
Full-fat dairy products like cheddar cheese, sour cream, whole milk yogurt, and full-fat cottage cheese
Trail mix with a variety of nuts, dried fruit, and chocolate or peanut butter chips
Bagels with cream cheese (add lox if you like salmon!), sliced avocado, or peanut butter
Pizza of any kind, but you can make it a more balanced meal by topping with veggies
Tuna or chicken salad made with full-fat mayonnaise
Energy or protein bars made with wholesome but calorie-dense ingredients, like nuts and dates
Mashed potatoes with butter (in fact, butter is a great high-calorie addition to any meal or snack)
Whole eggs scrambled with cheese
Thinking about nutrients
Nutrients provide our bodies with energy, repair cells, maintain healthy bones, and more. We need large portions of macronutrients each day — carbohydrates, fat, and protein — and smaller portions of micronutrients (vitamins and minerals).
Carbohydrates are our bodies’ preferred source of fuel, especially for our muscles and brain. Carbohydrates are found in whole grains, starchy fruits and vegetables, honey, some dairy, and many other foods.
Fiber is a type of carbohydrate. It’s a plant-derived nutrient that cannot be completely broken down by the digestive system. High-fiber foods include chia and flax seeds, popcorn, oats, almonds, beans, whole grains, avocado, raspberries, and lentils.
Dietary fats are a major source of energy for our bodies. We need both saturated fats — from meat, dairy, butter, and some oils — and unsaturated fats — found primarily in plant foods.
Protein helps heal and rebuild tissues. The USDA Guidelines (PDF) recommend that adults eat 0.36 grams of protein per pound of body weight each day to meet basic nutritional requirements — but during treatment for breast cancer, you may need more protein than usual. You may want to talk to a registered oncology dietitian to find out how much protein you need.
Good sources of protein include fish, poultry, dairy products, nuts, dried beans, peas and lentils, soy, and lean meat.
Micronutrients like folate and vitamin D, which support immune function, energy metabolism, and more, are highest in fruits, vegetables, whole grains, lean protein, and dairy products.
Minerals like calcium, magnesium, and iron support bone health, muscle function, and more. Mineral-rich foods include dairy products, beef, shellfish, whole grains, and dark, leafy greens.
Getting plenty of energy (calories) and nutrients is key to gaining weight back. If you’re not seeing results, let your doctor or dietitian know so you can make a plan together.