Ha! I started using it because it's just so easy for me to skip breakfast and/or lunch. I'm not replacing food with it. Just works better than not eating.
You should try intermittent fasting. The first two or three weeks are hard, but after that its easy, and really seems to sort out insulin sensitivity (or thats my guess from reading the science and "gut" feeling - pun intended). No feeling tired after lunch.
[1] The joyless tech-utopian future for ascetics nerds who decided their humanity wasn't optimized for maximum productivity.