I have done variation but only up to 800 calories. I never really had the guts to try more calories as I figured it might affect the weight loss program. While the original protocol is 500 calories, people tend to vary because of health problems, fear of side effects and if they are under medication.
I have hypoglycemia and the 500 cal diet didn’t work well for me. Hence, I switched to 800 calorie diet which though still had few mild effects such as gas, constipation still worked for me. Planning to do another round with 1200 calories. 🙂
The effect of such variation in the hcg diet program is unknown. However, many dieters report weight loss even after switching to high calories.