Sleep is therapeutic
You do not want to be yawning at a morning meeting with clients. While, nobody can tell as to how many hours of sleep is required to function in the mornings, sticking to a routine helps.
Eat right and drink plenty of water
It is important you get the right amount of nutrition on the road. Avoid ‘junk-foods’ during meals. Minimize fried and fatty foods in your meals. Keep drinking water at regular intervals.
Avoid drinking too much coffee
You might have to schedule several meetings at coffee shops. Avoid loading up on coffee at every meeting. Get a bottle of water, or a bottle of juice, for a change.
Pack enough medicines
Do not get lazy -- ensure that you buy all your medicines before you leave. Keep them in your backpack at all times.
20 to 30 mins of exercise in the morning, inside your hotel room should be enough to keep you from gaining weight. Exercise sets the pace for the day. A half-hour walk in the mornings too will do, if nothing else.