Jet lag can be completely debilitating, and it may take you days to recover. Rather than struggling with fatigue, you might find you can reset your body clock just by missing out on a meal or two.
A study (linked below) by Dr Clifford Saper of Harvard University suggests that animals have two internal clocks. One of these is tuned to sunlight, so we tend to sleep when it is dark and wake when it is light. The other clock is tuned to availability of food. When we are hungry, our bodies will keep us awake to try to make us seek out food.
If animals have access to food only during their normal sleep cycle, they will shift most of their circadian rhythms to match the food availability.
You can exploit this to help beat jet lag in advance. Fast for 12 to 16 hours to reset your food-led body clock. When you eat next, your body will believe it is breakfast time and you can start afresh. Plan ahead for your next trip, and you can hack your body into waking up when you need to.
Differential Rescue of Light- and Food-Entrainable Circadian Rhythms [Science Magazine via WonderHowTo]