You can eat junk and still curb weight gain.
Now hear me out on this one. If you are steadfast in getting in a green smoothie or 2 every single day, I'd wager you will in fact maintain a healthy weight if not lose some weight.
This is because not only are you slowing the process of glucose uptake as I already mentioned (which will turn into fat otherwise), you are also more likely to balance out hormone levels.
Blood levels of hormones such as estrogens, progesterones, and prolactin influence tissues like the breasts, ovaries, and uterus, are dependent upon your diet.
One mechanism that contributes is the recirculation of hormones. For example, estrogens, made in the ovaries and the adrenal glands, are secreted into the blood stream and then pass through the liver and then into the intestine.
To prevent re-absorption by the intestine, these estrogens are combined in the liver with a non-absorbable substance.
A poor diet encourages growth of the bacteria in the colon that allow those once non-absorbable estrogens to now become "free."
Then the “free” estrogen is absorbed back into the blood stream, resulting in higher total levels of estrogen. This re-absorption of estrogens can contribute to development of breast cancer or hormonal imbalances.
Fortunately, fibers present in fruits & vegetables help block the re-absorption of “free” estrogens found in the colon. This means better hormone balance, less estrogen dominance and less difficulty losing weight (4).