- Sauna
- Carb restriction like Keto
- Epsom salt bath
- high-intensity cardio
- eating less
- keeping active all throughout the day like instead of getting public transport you'd walk most of the distance back to your house but on foot or cleaning the house etc.
Do some or all of them and you could lose a great deal of water weight.
I lost twenty pounds when I stopped cooking meat and stopped buying it consciously. My gf is vegan though so that has a lot to do with it. I lost it in 2 months.
You lost muscle mass, not fat. Muscle is more dense than fat and so it holds more weight so that doesn't mean you leaned out it just means you didn't maintain your muscle mass and burned a little fat in the process.
Reducing your protein intake is a sure way to lose all of your gains in the gym and leave yourself susceptible to excess skin.
Unless you look like a hideously bulky WWF wrestler then I don't think it's a good idea to not eat protein