Many people train in the mornings (on an empty stomach), but is it beneficial? To be honest, it's a personal thing, some people like to lift weights in the morning, and others dislike it. I say the morning as that is when you are most likely going to have an empty stomach.
I have performed weight training on both an empty stomach and a during the day in between meals, and my personal favorite is in the mornings. I just feel more 'up' for the workout in the mornings, and have felt sluggish training between meals. This is a personal thing, as I know people who hate training in the mornings.
I honestly don't think there's a difference, simply because it works for some and not for others. If training on an empty stomach was just plain bad, then how can it work for some people? Some people mistake feeling tired for a lack of energy (they are different). If you're someone who struggles to get up in the morning simply because you love your sleep, then you'll struggle to lift weights in the morning. There are ways you can improve your 'get up and go', and if you do improve that then I am sure your morning training session would improve. It is partly a mental thing - if you're still half asleep mentally, you're not going to be able to lift a lot of weight. You could get enough sleep but still feel tired as you're simply not a morning person.
My advice is to workout when you can fit in a session (not everyone gets to choose when they can train due to work and family) and to train when you feel your best - that could be in the morning, lunch time or evening. Training is a very individual thing, and what suits one won't necessarily suit another.
Lee Gregory Fitness