Listen...

With any restrictive "diet" all you are doing in the short term is limiting your caloric intake. So sure you are going to lose weight.

Here's the real deal...

If you want to lose weight simply eat less calories than you expend over a period of time. The problem with that is you are losing muscle at the same time.

If you want to gain weight simply eat more calories than you expend over a period of time. The problem with that is you are gaining fat at the same time.

If you want to lose weight and maintain muscle mass you need to eat lower calories, but with higher protein and you need to lift weights.

If you want to gain weight and also gain muscle you need to eat higher calories and higher protein and you need to lift heavy weights in a rep range that encourages muscle hypertrophy.

It's a simple as that. Anyone that says anything different is selling you a bunch of bullchit and merely parroting anecdotal evidence.

Listen to me... Your body needs vegetables as well as meat (protein), healthy fats and even carbohydrates to properly function long term.

Everybody is always looking for the damned easy way out, but there is no easy way. It all requires hard work and dedication.