Generally speaking I am wary of ANY diet that excludes an entire group of food- or macro- examples are:
At the end of the day there must be a caloric deficit to initiate weight loss. All of the above can do that. Honestly any calorie deficit will initiate weight loss- if you ate snickers bars all day but the total calories consumed was less than the total calories expended- you would lose weight.
The key is exactly what kind of weight are you losing- is it fat or other tissue, i.e., muscle?
The more muscle you have, the less fat you will have. So, when you are losing weight it is vital to make sure you have enough protein to keep the muscle. This will give you the results you want. Additionally, it is important to have carbohydrate and fats as well- they are all vital to health.