Obesity has shown to be a risk factor for most, if not all cancers. This subject is well studied and at this point is very convincing. On the other hand, starvation or reduced calorie intake greatly decreases risk of most cancers. Overeating in general causes an increase in growth factors. Cancer is very growth-dependent and requires many of these growth factors to function. Another theory states that increase in weight leads to increases in organ size or an increase in the number of cells that could possibly turn malignant.
In obese individuals, as the adipose or fat cells become larger, they become resistant to insulin stimulation. It is almost as if the cells are saying that they are full and don’t require any more calories. The body, on the other hand, has to clear the blood sugars, or glucose, so it increases its secretion of insulin. Insulin has many stimulatory and growth functions that tumor cells like and require.
Increased calorie intake, especially of fats and refined carbohydrates like sugars also decrease immunity. Immunity is another defense against cancer. Immunity can recognize cancer cells and destroy them. If we lower our immune response, we increase our cancer risk.
Remember, increases in weight increase our risk of most, if not all, cancers. Some of them like endometrial cancer increase our risk two to three times. A final note: In one study, 81% of Americans underestimated their intake of calories by around one-third or 700 calories. Weight will be further discussed on a lot of individual cancers. With Americans becoming more overweight, especially our children, we may see increased rates of cancers in the future.