I would like to ask whats the quickest way to regain energy or maintain energy levels after an upset stomach. Assume that the upset stomach is a one off thing.
My question has to do with preventing muscle loss after an upset stomach.
Thanks
What exactly do you mean by energy levels? Accept the fact that your body will sometimes fail you, just let it rest and get back to work as soon as you feel well.
Any muscle loss due to not being able to eat and train properly for such a short while is miniscule.
I read that Olympic level lifters will see a 10% loss in performance after 4 weeks of no training. To put that in prospective, that's going from squatting 300 to 270, and it's not going to take those folks a long amount of time to regain that (barring other injuries or problems).
Exact numbers are hard to peg because of various factors that go into muscle atrophy:
One-off short duration issues like a cold or stomach bug aren't going to do much other than disrupt your normal workout schedule. Whenever you come back from an illness, ramp back up. Your body's glucose and ATP capacity is probably on the ropes because you've been calorie restricted or just not eating right (normal for being sick).
Plenty of people have make training on an empty stomach a regular practice - see leangains.com An illness induced fast of a day or less will have little effect on your muscle mass. Fast actually increase Growth Hormone secretion. Besides, do you really think people are so fragile? How would humans have survived our past with the many times where food was scarce? I myself have had excellent workouts the day after a stomach illness and no food ~20 hours. It was very mentally focusing.