The 1000 calorie diet and other hcg diet variations such as 800, 1200, 1400 and 1500 are available due to the following reasons.
1. Health condition
2. Inability to withstand low calories
3. Under medication
Not everyone are able to tolerate 500 calories a day and might indulge in cheat day often. This can hinder weight loss. Few might even complain that the hcg products are not incapable. To avoid such issues, many hcg brands come up with variation in hcg diet program so that users can have from the approved lists and still lose weight with hcg.