PE progress influence carbs or diet or weight loss

Dear friends,
I am doing PE often regularly since 3 years except some breaks in between. Recently I observed something!. I have got good progress in length and girth 2 months ago. I started some diet control by reducing the carbs + some cardio (HIIT) to reduce my weight around that time when I was having a good progress in my PE. I got a my weight reduced by 6kg but I observed something strange which the reduce in PE progress and my gains slowly declined ( length and girth reduced). Any idea what is wrong? Please share

Thanks