Diet and exercise are the two main pillars of a healthy lifestyle. For both weight management and physical fitness, they are equally important and go hand in hand. But how do they relate to one another? Scientists suggest that coordinating your eating and workout schedules can improve results.

Our busy lives make it oftentimes hard, if not impossible, to always maintain a health-promoting regimen. We eat at different times, skip meals, snack in between, work out irregularly. While flexibility can be both a necessity as well as a virtue, keeping to a schedule has advantages that are hard to substitute.

“Every organ has a clock,” said Dr. Satchidananda Panda, a researcher at Salk Institute for Biological Studies in La Jolla, California. “That means there are times that our livers, intestines, muscles and other organs work at peak efficiency, and other times when they are – more or less – sleeping.”

Lab tests (http://www.sciencedirect.com/science/article/pii/S1550413112001891) showed that when mice were allowed to eat any time they wanted, they soon gained weight. But others who had access to food for only eight hours a day did not, although they consumed roughly the same amounts. “Metabolic cycles are critical for processes such as cholesterol breakdown, and they should be turned on when we eat and turned off when we don’t,” Dr. Panda said in an interview (http://todayhealth.today.msnbc.msn.com/_news/2012/05/17/11746549-how-to-avoid-weight-gain-eat-on-a-schedule?lite) with MSNBC Today/Health. Squeezing in quick bites or snacking throughout the day and at night can throw off these normal metabolic cycles, he warned.

What about exercise? While there is no ideal time for running or lifting weights – early risers may prefer the wee hours before the day starts, night owls may put it last on their to-do-list – there is the question of how to maximize the benefits.

For those who aim for weight loss, it can be important to coordinate their food intake, both in terms of quality and quantity, with their work-out schedule. Studies (http://journals.lww.com/acsm-msse/Citation/2003/05001/Effect of Pre Exercise Feedings on Endurance.1663.aspx) have suggested that intense physical activity like running, swimming or bicycling on an empty stomach can increase fat burn and therefore promote weight loss.

Other experts, however, caution against pre-exercise fasting. They say running on empty may help you get rid of fat faster, but you won’t have enough energy for a more rigorous training. “If you have a long, hard run without breakfast once a week, that hard run will train you to burn fat,” said Dr. Ron Maughan, (http://www.msnbc.com/id/37492881/ns/health-fitness/t/get-rid-fat-don’t-eat-workout/), a sport science professor at Loughborough University in Great Britain. For the rest of the week, however, he recommends eating plenty of carbohydrates, provided you can keep exercising. Also, if you allow your body to become too depleted, you may be tempted to overeat afterwards, thereby undoing all your good efforts.

“People often skip pre-exercise meals due to lack of time or not knowing what to eat,” said Manuel Villacorta (http://health.usnews.com/health-news/blogs/on-fitness/2011/10/13/best-workout-foods-what-to-eat-before-a-workout), a registered dietitian and spokesperson for the Academy for Nutrition and Dietetics. He recommends consuming appropriate amounts of carbohydrates and protein to keep you fueled and give you energy and a steady stomach. But be careful: “Even the best foods can come back to haunt you mid-workout if not allowed to properly digest,” he said, “so it’s best to eat 45 minutes to an hour before you work out – longer after heavy meals.”

Some foods settle more easily and enter the bloodstream faster than others, he explains. These should be your preferred choices. Avoid those that make you feel sluggish or cause you having stomach cramps.

After you finished exercising, your muscles need to recover and nutrients need to be replenished. Focus on protein, especially after resistance training, and carbohydrates for refueling. Even if you are not hungry after being active, you must rehydrate by drinking plenty of water and perhaps some diluted juice or sports drink.

Obviously, there are no clear-cut rules that satisfy everyone’s needs. Experts recommend you pay attention to how you feel during exercise and how your performance is affected. Only your own experience can guide you and help you get optimal results.

Timi Gustafson R.D. is a clinical dietitian and author of the book “The Healthy Diner – How to Eat Right and Still Have Fun”®, which is available on her blog, “Food and Health with Timi Gustafson R.D.” (http://www.timigustafson.com), and at amazon.com. You can follow Timi on Twitter (http://twitter.com/TimiGustafsonRD) and on Facebook (http://www.facebook.com/TimiGustafsonRD).