I've had this before on previous rounds. For me it was food boredom essentially. I just had no appetite. I've found that trying a few new recipes that look exciting, or even having a favorite meal Whole 30 style (for me it's something taco related - taco salad or something I call a potaco which is a potato loaded with taco topings) makes a huge difference. Also if you've been eating the same foods for each meal, try varying it a bit. This will pass as you get used to and start looking forward to various Whole 30 meals.
It may also be that when you are eating quality and