Simple. Just try to get 30-35 grams of fiber per day.
It works because high fiber foods are healthy and tend to be filling, so you won't get hungry very often. Not only that, but trying to eat more of something is psychologically less difficult than trying to eat less.
Combine that with 15-20 minutes of high intensity interval training.
Then adjust as necessary. If you're working out more, set a goal for protein intake.
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