Starving yourself is not ideal and won't be sustainable long term. Maybe the weight you're losing isn't even fat but muscle, and improper nutrition certainly won't do any good for your joints either; in fact, it may be one of the cause of the muscle and joint soreness your experiencing.
What you eat is more important than how much you eat. You mention pizza, which is somewhat of a junk food. What exactly is your diet like?
It's probably mostly fluid, most people can lose 7 to 10 lbs pretty easily by just not eating.
What worked/ works for me was no wheat products (cereal, Bread, Hot Dogs, etc.), with that said I do eat bran buds in the morning with my yogurt, the bran helps me feel more full, very little milk products (only yogurt) because what do baby's eat to get fat, milk, lots of water, no refined sugar products and portion control. Staving yourself f's with your glucose levels and you dont want your body spiking and crashing. If you just diet without exercise, your body will become super efficient and will burn calories at a slower rate and when you come off your "fast" you will notice you will gain weight easier. The key, and this sounds common sense, is you want to be constantly in a calorie deficit. Some people say its a fad, some people swore by it, I do subscribe to the ACV cult, personally I find I have less bloating and my glucose does not spike and crash. I eat twice a day, once mid morning around 10am to 11am and once late afternoon around 4pm to 5pm
I dont eat boxed foods and I avoid the middle of the grocery story, I shop mostly along the outer walls. All the processed crap is in the middle of the store, usually your veggies and meats are along the outside walls.
