So I started a 30 day paleo diet challenge.  I ate extremely healthy before, except for the daily beer, handfull of chips/candy.   On August 1st, I cut out all refined sugar, all artificial sweetners, all grains and processed foods.   
Eating the following -    
Grass fed beef/free range chickens/pig/buffalo, free range eggs, tuna/salmon 
organic vegetables/fruits 
nuts - macadamia/almonds 
oils/fats - coconut milk/olive oil/avacados   
Drink my morning coffee, then only water the rest of the day.   
Being 3 weeks in, I've dropped almost 15lbs.  The first 3-4 days, I felt AWFUL.  My body was craving the sugar I was putting in every night and I was waking up in the morning feeling like I drank a bottle of jack.  Had headaches, would get dizzy while working out and no energy....   
After the first initial shock was over, I feel absolutely great now.  I wake up feeling energized, ready to go all day and more focus.   
If anyone is interested in more info, shoot me a PM