Hello there and thank you for your question!
The Whole30 diet is a diet that avoids sugar, alcohol, grains and legumes. It is similar to another diet called the Paleo diet. For some people, they have used the Whole30 diet as a way to find food intolerances, but many have used the diet for weight loss.
Is the Whole30 safe? Or is the diet healthy? Definitely the diet is safe and is healthy. But the main question I would ask you is if you can sustain a diet that restricts you. I think with the Whole30 or Paleo diet, one of the biggest limitations is the restrictions that these diets place on the person. Can you give up foods that are also good for you like whole grains and legumes? And both of these diets limits the amount of sugar, but that also includes natural sugars that are found in fruits.
If you are trying to lose weight, this page is great resource on tips to lose weight. I would also add that losing weight takes time and patience. It is also not always a straight line...you may have some steps backwards but that shouldn't discourage you.
Hope that helps!