My routine before visiting the gym usually involves me finishing work, relaxing for a little while then eating and going to the gym. I've always eaten beforehand simply because I'm hungry at that point, however I've recently started doing situps and other ab exercises in addition to the rest of my weights work.
Am I making ab excises un-necessarily difficult by eating beforehand?
You aren't making them any more difficult, but you're making it a little more difficult for your body to process the food, not on the chemical level, but rather on the physical level, you know, with all the motion around your stomach and with your intestines, etc.
Basically, if you have a 'strong stomach' and you don't really feel anything wrong while working out, you can easily continue your routine.
Some people, on the other hand, are so sensitive and have so 'weak stomach', they'd easily throw up or simply feel a bad sensation when processing the food like that.
You have to feel for yourself what your body is trying to tell you.
The general recommendations I've seen are to have an hour between eating and working out. This gives your stomach enough time to digest the worst of the food and get whatever quick energy it can from it.
If you eat when you get home, before relaxing, you should be able to separate the eating and the exercise by an hour easily. For me, I go straight from work to the gym--which puts me in with the gym rats and social hour :( but it's the only way I'll be consistent about going.
Other than that, @RiMMER's advice is sound. If you eat before hand, and you feel sick or are having a hard time performing to capacity give yourself more time between eating and working out. Your body is splitting it's energy between digestion and effort.
Also, consider what you eat before going to the gym. Carbs are harder for the body to digest than protein. In fact complex carbs take up to 12 hours to fully digest and be released as energy. If you work out in the afternoon, have your carbs in the morning and focus on protein and veggies with that meal before working out.
The most important thing with eating right before exercise is the strain it places on your heart. The bloodflow to your digestive tract is significantly increased for a while after eating. Forcing your heart to keep up that bloodflow and increase bloodflow to your muscles can cause a heart attack (depending on normal risk factors and everything else) as well as just plain decrease your performance if your heart can't keep up. Of course, if you want an "easy" way to raise your heart rate this might be a good thing, but you should definitely be careful and I would caution against it.
