Small amounts of weight gain are usually ignored by most of us, including your health care provider.
It has been shown that for each 11 pounds of weight you gain as a young woman (18-20 years of age is the most studied), translates into a 13% greater chance that you are going to develop the type of breast cancer that is hormonally responsive (also known as estrogen and progesterone receptor positive.
These studies include those who gained weight even by growing a bit in height, so the effects are thought to be greater in women who actually accumulated more body fat.
Being overweight or obese, and having greater amounts of body fat is carcinogenic (cancer risk increasing), at all ages.
Even if you are a healthy weight, maybe speaking to us about positive nutritional strategies to help keep you there.