The tiredness only lasts for a couple/few days, as your body switches from burning sugar (from crap processed food) to fat (from natural healthy steak, eggs, etc). Basically eat nothing that isn't in its original natural form.  

 I didn't eat processed foods before😀 Luckily my husband set a trend years ago, we eat only eggs and bacon for breakfast and such, so if something, I buried my snout into baked goods or a pot of soup.