That sucks; but not every diet is for everyone. Our bodies are all different, but you're right: if you plan on undertaking a massive weight loss plan (more than 30 lbs) you should probably have a doctor monitor you. Many insurance companies will cover this kind of care under a wellness plan, because let's face it: if you can lose a lot of weight in your 30s, you're probably going to have fewer health problems when you're older.