This and more.
I have switched to low sugar, low carb, and started working out five times a week, two days of lifting, three days of cardio with running 5K or more on the weekends and managed to lose 40 lbs in 8 weeks. That's over 15% of my body mass.
While the level of insanity that I endured for this is a bit much, I can attest to the fact that the amount of crap we add in American diets is excessive to the point of "we need to stop hurting ourselves"
The biggest guidelines that I have for myself is if it's designed to sit on a shelf for a long time, it's not designed to be consumed and carbs are great, only if you have a plan to burn them off.