Just thinking about eating causes your body to start secreting insuline, a hormone that helps keep blood sugars (glucose) under control. Insulin is made by the pancreas. As you eat, more insulin is released, in response to the carbohydrates in the meal. Insulin is released when you eat protein-rich foods, but at a slower rate. If your pancreas is functioning properly, the amount of carbohydrates in what your eating usually determines how insulin released.

As you digest carbohydrates, they go into the bloodstream as glucose. To keep blood sugars levels under control, insuline signals the cells the cells in your body to take in glucose from the bloodstream. The cells use some of glucose for energy and store some for later use. The glucose is stored depends on the type of cell doing the storing. Muscle cells store glucose as glycogen. Liver cells store some glucose as glycogen and convert some to fat. Fat cells store glucose as fat.


Proteins give your body amino acids — the building blocks that help your body’s cells do all of their everyday activities. Proteins help your body build new cells, repair old cells, create hormones and enzymes, and keep your immune system healthy. If you don’t have enough protein, your body takes longer to recover from illness and you’re more likely to get sick in the first place.


Carbohydrates give you quick energy — they quickly go into your blood as glucose (blood sugar), which your body uses for fuel first, before turning the leftovers into fat.

Fruits, vegetables, bread, pasta, grains, cereal products, crackers, dried beans, peas, and lentils are all good sources of carbohydrates. Many of them are also good sources of fiber, which your digestive system needs to stay healthy.

Sugar (white and brown), honey, and molasses are also carbohydrates. But these types of carbohydrates are high in calories and don’t offer any other benefits (like vitamins and minerals). Whole grains and fruits and vegetables are healthier sources of carbohydrates than refined grains and sugars.

Vitamins and minerals

Vitamins keep your bones strong, your vision clear and sharp, and your skin, nails, and hair healthy and glowing. Vitamins also help your body use energy from the food you eat.

Minerals are chemical elements that help regulate your body’s processes. Potassium, for example, helps your nerves and muscles function. Calcium helps your teeth and bones stay strong. Iron carries oxygen to your cells.

If you eat a balanced diet with enough calories and protein, you’re probably getting enough vitamins and minerals. But if you’re receiving treatment for breast cancer, this may be a challenge. And certain treatments may sap your body’s supplies of some vitamins or minerals.

It’s also important to remember that there is a big difference between getting your nutrients through food and taking supplements (vitamins, minerals, and herbals/botanicals). Vitamins and minerals work together in your body in very complex ways, affecting each other’s absorption and processing and influencing how your body functions. When you get your vitamins and minerals through eating foods, it is often easier for your body to maintain a balance of these nutrients. When you take a supplement, such as a vitamin C or E tablet, you’re getting a highly concentrated dose that you would probably never get from food.


Water is necessary for life, which makes it vital for good health. Water makes up about 50% to 66% of your total body weight. It regulates your temperature, moves nutrients through your body, and gets rid of waste. Breast cancer treatment can sometimes cause diarrhea or vomiting. Losing a lot of fluids plus the chemicals and minerals they contain can lead to dehydration.

In general, it’s a good idea to drink 6 to 8 glasses of water a day. If you’ve lost fluids because of diarrhea or vomiting, you need to replace both the fluids and the essential ingredients in them. Chicken or vegetable broth, tomato juice, fruit juices, and sports drinks such as Gatorade are examples of fluids that can help you replace the vitamins and minerals your body has lost.