Hi Smiley10, welcome to 3FC!
All of the reviews I can find are on sites that get paid to promote the program. You'll notice that when you click the link to go to the actual site, the link is through ********* which is a service that tracks links and purchases, then pays the originating site a commission. For this reason, I would not trust anything those sites say.
They aren't really reviews, they are advertisements.
The sunslim diet is an ebook you purchase for $24.95. The site is filled with red flags, and I personally would not buy the plan.
Instead, I would highly recommend that you consider a plan that is well known to be effective, safe, and healthy. I love that you have joined a gym and that your goal is getting healthy
Have you considered a diet and exercise program such as Eating for Life / Body for Life by Bill Philips? We have a thread in our General Diet Plans forum for this program, and the program has a great reputation.