I am experiencing the same issues. When I spoke to my nutritionist, she said it's a defense mechanism from your body. It's almost trying to hold on to your weight since some of it was lost so quickly in the prior weeks. Now that I am in week 5/6, I am starting to see the numbers change finally. But I was stuck for two weeks and it made no sense! Just like you, I couldn't believe how eating 1000-1200 (so much less than I used to eat) wasn't making any difference.