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Eating around exercise

Sarah: My husband and I recently started exercising together because we both want to lose weight. He insists you should never work out on an empty stomach because you'll burn muscle and won't get "ripped." I've heard you burn more fat by exercising first thing in the morning on an empty stomach. What's the truth?

The truth is there is no easy answer to this question. It is one of the most hotly debated topics in the fitness and scientific community. You can find a study to support the fed exercise theory (food in the stomach), the fasted theory (empty stomach) and just about everything in between.

Search "Exercise on an empty stomach?" online and you'll find dozens of "experts" selectively summarizing studies to support their beliefs or sell their products. Amidst all the misleading marketing and manipulated studies there are a few research-backed "truths" when it comes to eating around exercise. In an attempt to make a complex subject more entertaining and comprehendible, I've narrowed the agreeable key points down to a "Top 10 List."

1. The body uses glucose (carbs) in the blood stream and glycogen (carbs stored in muscles) during strenuous exercise for fuel.

2. Glycogen, glucose and insulin levels are lowest in the morning when you haven't eaten in 8-12 hours.

3. Insulin hampers the body's ability to break down fat. When insulin, glycogen and glucose are low, the body is forced to burn fat for fuel.

4. When you eat before a work out your body burns the energy supplied by the food before it taps into anything stored in the body. You might have heard the rumor that the body can't digest during exercise. That's a myth. Digestion is slower during exercise, but it doesn't stop.

5. Studies show morning cardio is more effective for raising your metabolism and keeping it raised longer post-workout, so you're likely to burn more fat for the duration of the day.

6. The body burns amino acids (protein) in muscle for fuel under EXTREME conditions. EXTREME conditions = Lance Armstrong, Michael Phelps, people with low body fat exercising at "hit-the-wall" intensity for an extended period of time.

7. The average person has enough stored fuel reserves to work out at moderate to high intensity on an empty stomach for 60-90 minutes before burning anything worth keeping. Despite all the athletes endorsing "performance enhancing" gels, powders, liquids, or other science projects, there is no monetary or oral consumption necessary for a great workout.

8. It's more important to focus on your post-workout meal (50/50 carbs and protein) and a balanced diet throughout the day to fuel muscle growth and keep your metabolism humming. Be sure to watch the fat intake post-workout because fat significantly slows digestion. Although a hamburger is high in protein, the muscles will have to wait much longer to utilize it because digestion will be held up breaking down fat.

9. Not all exercise is ideal on an empty stomach. Research indicates greater benefits from doing cardio on an empty stomach as opposed to strength training. The most likely explanation is that the short bursts of intensity in weight lifting require greater performance focus, rather than simple endurance. Just like we lose focus at work as the lunch hour draws nearer, we lose the focus needed to perform an effective push up when we're hungry.

10. Although you burn more fat exercising on an empty stomach, at the end of the day, it's still calories in versus calories out when it comes to weight loss. Even if cardio on an empty stomach is better for burning fat, it won't make or break your weight loss goals.

Personally, I'm a big advocate of cardio first thing in the morning. The leanest and meanest bodybuilders and trainers I know swear by it to get "cut." I can even direct your husband to several famously "ripped" bodybuilders who boast of AM cardio benefits on their blogs. Of course, I am not a bodybuilder or a scientist. If you dig hard enough, any advice can be refuted.

The bottom line is that the best exercise plan is whatever works for you. If you just can't find the energy to workout on an empty stomach, eat something light before hand. If the thought of waking up early to do cardio turns your stomach, work out a few hours after your last meal. If you get to the gym at 4:30 after a long day at work and can't focus over your growling stomach, EAT something.

Don't forgo a workout because you're too concerned about when and what you ate last. As Nike says, "Just Do It."

Sarah Frieden is a certified personal trainer and group fitness instructor in Park Rapids. Please email your health and fitness questions to All questions will remain anonymous.