Why do some people with breast cancer gain weight?
Many people gain weight when they are treated with chemotherapy and steroids. Your extra weight may hang around and increase after chemotherapy if you also take hormonal therapy (tamoxifen or an aromatase inhibitor). If your body shifts into menopause because of chemotherapy, there's a tendency to gain weight.
This weight gain may be because of the enzyme lipoprotein lipase (LPL), which is controlled by insulin.
LPL sits on the surface of cells and pulls fat out of the bloodstream and into the cell. If LPL is on a muscle cell, it pulls fat into the cell where it’s used for fuel. If LPL is on a fat cell, it pulls fat into the cell and makes it fatter.
It’s important to know that the hormone estrogen suppresses LPL activity on fat cells. This could be one reason why some women gain weight after menopause or after breast cancer treatment that dramatically decreases estrogen levels. With less estrogen in the body, LPL can pull fat into fat cells and store it there.
The shock of a diagnosis, the disruption of your life, getting through and beyond surgery and radiation, the strain of relationships at home and at work, financial stress, and less physical activity all may contribute to weight gain. During chemo, extra fluids and steroids together with less physical activity and a yearning for sweets all combine to cause weight gain. And like many people, you may be certain that taking a hormonal therapy medication makes you gain weight and makes it nearly impossible to lose weight. But two of the major studies conducted in the United States and Canada by the National Surgical Adjuvant Breast and Bowel Project (NSABP, a cooperative research group) showed that women taking a placebo (a sugar pill) were just as likely to gain weight as women taking tamoxifen. (Because aromatase inhibitors are relatively new, research on aromatase inhibitors and weight gain hasn't been done yet.)
Losing weight becomes much harder as we grow older, but it can still be done with careful diet changes and exercise. Be nice to yourself; don't punish yourself.
There are lots of good reasons to maintain a healthy weight. You'll feel stronger, have more energy, and boost your self-esteem. Also, research has shown that being overweight can increase the risk of the cancer coming back. Some studies have shown that women who were overweight at diagnosis had about a one-third increased risk of the cancer coming back. (For example, the risk could go from 6% to 8%, because one-third of 6 is 2.) Other studies showed more than a five-fold (5 times) risk increase (for example, the risk might go from 6% to 31%).
Learn more about Being Overweight as a risk factor for breast cancer in the Lower Your Risk Section.
Do you need to count calories?
Many people believe that if you eat fewer calories than you burn each day, you’ll lose weight, and if you eat the same number of calories that you’ll burn, you’ll maintain a healthy weight. This plan works for many people, but not all.
If you’re counting calories, it’s important to think about what you’re eating. Say Jane eats 1,200 calories a day of cake, cookies and white bread. She’s probably not going to lose any weight. Betty eats 1,200 calories a day of fresh vegetables and fruit and lean protein. She’s probably going to lose some weight and get a lot more nutrients from her food. Counting calories is only part of the weight loss equation.
And counting calories is only one way to lose weight. Because the hormone insulin plays a major role in how your body uses and stores fat, some research suggests that eating foods that keep insulin levels steady throughout the day — lean meat and fish, poultry, vegetables, and fruit rather than foods like sugar, candy, white bread, and crackers — can help you maintain a healthy weight.
The first thing to do if you want to lose weight is to talk to your doctors and a registered dietitian about a safe and sensible plan designed specifically for you and your needs. Your doctors may want you to wait until you have completely recovered from treatment or any other health issues you may have.
These steps can help you lose weight after treatment:
- Assess Your Weight
- Create a Healthy Eating Plan That Includes Exercise
- Make Healthy Food Choices and Lose Weight
"In terms of central body weight gain, some women are more responsive to a lower carbohydrate/more simple sugar diet than to a low-fat diet. But there are wide individual variations, and you should work with your healthcare provider to design the best weight loss diet for you."
— Cyndi Thomson, Ph.D., RD
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