Over the years, I've probably consumed enough quick energy drinks and snacks to turn me into a permanent turtle by the time I reach 40. Like a car burned out on nitro, I'm now a semi-sluggish, clunky and rattly mess.

Fortunately, I've discovered a few foods that don't seem to do much more harm.

The first one is just plain tomatoes. When it comes to balancing out my blood sugar in a hurry, and getting rid of enough fatigue to let me get on with the day, a single average-sized tomato works just fine.

I have a friend who was a taekwando competitor, and she swore by bananas. Though for me they're too starchy for a standalone snack to provide lasting energy, she had enough of them during competitions to be at the top of her game until she'd won her medals.

Another source of quick natural energy comes from the archives of departed, but kindly remembered chef James Barber. Submitted by Doug Temoin, Instant Energy is very simple: a pear sliced into eighths, and either four half-slices of processed cheese or eight quarter-slices of traditionally made cheese. People interested in packing this up for their lunches can soak the concoction in lemon juice overnight to keep the color.

The last healthy source of energy I use is Function Drinks' Alternative Energy drink. Made with cane sugar, it doesn't give me a temporary energy spike when I drink it, and it even gives me a feeling of well-being while I go about a busy day. The only downside to it is that I seem to develop a tolerance after a few days, but if I use it just a few times a week it works better each time.

Since your metabolism is different from mine, different foods will have different effects, so you may be able to make an experiment out of seeing what works best for you over a few days, just by varying what you eat, when you eat it, and how much. Good luck!