Is Your Diet Promoting Fatigue?

“I’m usually so tired by 4 p.m. that I just have to eat something with sugar — like cookies, with a tall coffee mocha on the side.” 

38-year-old male triathlete 

“The problem isn’t really my weight — I just don’t have any energy to work out.”

42-year-old female distance runner

Lack of energy is one of the most frequent problems I hear about from endurance athletes. But trying to reboot with whatever food or drink looks appealing at the moment can make the fatigue problem worse. 

Let’s take a look at the big three nutrition mistakes you DON’T want to make…

Caffeine: The Upper and Downer

The Upper

About 70 percent of the U.S. population uses coffee. Although it is typically consumed to improve alertness, in recent years, coffee’s benefits to sport performance have been proven without question.

Research has shown that as little as 1.4 to 2.7 milligrams of caffeine per pound of body weight is enough to make a significant improvement in performance. Roughly speaking, that’s between 150 and 300 milligrams of caffeine, or an 8 to 16-ounce cup of joe. Non-coffee drinkers can easily find caffeine in sport gels and energy drinks.  

Caffeine can also help to reboot glycogen stores, which become depleted after exercise. When paired with high glycemic index carbohydrates, glycogen levels can be restored as much as 60 percent higher than if carbohydrates are consumed without caffeine. At the right dose and at the right time, caffeine can help athletes stay alert, improve performance, and aid in faster recovery.

So, why include caffeine as one of the big three fatigue-promoting “foods” in the diet?  

All drugs have a threshold, or optimal dose — more is not better. And caffeine is no exception. So how do you know if you’re over your tolerance limit? Typical warning signs include irritability and headache. But these symptoms may be mistakenly attributed to being tired. Although the effects of caffeine can be felt within 15 minutes of consumption, peak concentration in the bloodstream takes at least one hour.

Anticipation of immediate relief from fatigue following caffeine intake can lead to caffeine overdose. The clearance of caffeine from the bloodstream can take over six hours. Late-afternoon attempts to improve alertness with caffeinated drinks may ultimately end up interrupting sleep patterns, which can lead to sleep deprivation.

The stage is then set for food choices that can increase fatigue the following day. 

The Downer

Caffeine causes interrupted sleep cycles. And interrupted sleep cycles caused by caffeine (or alcohol) result in hormonal changes that promote unhealthy eating. 

The hormone ghrelin was discovered in 1999. Termed an “orexigenic” hormone, ghrelin production is increased in response to sleep deprivation — as though the body knows it needs more calories to be awake and functioning.

When ghrelin levels go up, so does appetite. Research performed with sleep-deprived graduate students at the University of Chicago showed a clear connection between sleep and calories. The less sleep they got, the more calories they consumed. And the students chose high-fat, high-sugar snacks over healthy choices like fruit or whole grains. 

Sleep deprivation also depresses the hormone leptin, which is termed an “anorexigenic,” or appetite-depressant hormone. Inadequate sleep will tip the balance in favor of ghrelin production relative to leptin.

The take-home message is clear: Less sleep leads to more food and calories.  

See also Does Caffeine Help You Cruise — or Crash

Fat: Friend or Foe?

It’s late. You’re tired and hungry. Convenience and hunger sometimes send even the most health-conscious athlete to the closest fast food restaurant. High-fat foods are deliciously displayed on the neon menu. And despite the best intentions, a double cheese burger and the kids’ leftover fries end up on your plate. 

The metabolic effects of a fat load (that is, a lot of fat eaten in a short time period) have been extensively studied by researchers interested in cardiovascular health. Long-term effects include plaque formation. But it turns out that in the short term, a 50-gram load of fat constricts arteries — effectively reducing the diameter of the artery.

Although temporary, blood flow to the heart and muscles slows — much like a clogged sink drain. The slowed delivery of oxygen and nutrients starves the heart muscle. The heart becomes stressed, as do all working muscles. And you feel fatigued. 

A late-night snack of cheese pizza and breadsticks can easily surpass the 50-gram threshold for fat intake. Most convenience meals or snacks are also high in sodium, adding to the low energy feeling due to water weight gain.

Like a swollen silt-filled river, the fat is eventually cleared from the bloodstream, and the bloat of excess fluid disappears. Unfortunately, the short-term effects of a load of fat and salt can keep you feeling sluggish and bed-bound — instead of out the door for that morning workout. 

Snacking on almonds or walnuts may be healthier for your arteries than deep-fried cheese curds, but even healthy fats won’t do much to raise your late-afternoon blood-sugar dip. Fat, whether omega 3 or saturated, doesn’t magically turn into glucose to raise blood sugar. One teaspoon of fat has 45 calories, about two and a half times as much energy as a teaspoon of sugar (which is 100-percent carbohydrate).

So grab an apple for a snack, and get some carbohydrates without a fast blood-sugar rise — and fall. 

Alcohol, Health and Fatigue

Many athletes enjoy relaxing with their favorite brew or a glass of wine after a workout. The health benefits of moderate alcohol consumption have been extensively researched. They include a reduced risk of cardiovascular disease, dementia and diabetes, as well as a longer lifespan. These benefits hold for all types of alcohol, not just red wine.  

However, alcohol makes the energy-zapper list when it comes to consumption and risk of fatigue. Unless alcohol intake is moderate (defined as one 5-ounce glass of wine or one 12-ounce beer for females), then the benefits start to slide into the problem area. Men get a little more leeway with regard to amount; moderate is considered as two drinks.  

During the first few minutes of exercise, glycogen is the most important fuel for contracting muscles. To keep the supply of glucose steady, the liver kicks in and starts to release glucose into the bloodstream for the muscle — eventually depleting its own supply of glycogen.

After a couple hours of exercise without additional carbohydrates, glycogen supplies are exhausted and must be replaced by carbohydrates eaten in the diet.  

Following exercise, replacement of total calories is often met by a combination of alcohol and food. Meeting some energy requirements with alcohol will likely leave you short changed on carbohydrates, since alcohol cannot be converted and stored as glycogen.

The end result is early fatigue due to a lack of energy stores for muscle contraction — and a drop in performance.

Alcohol can also impact the ability of the muscle to recover from muscle damage that occurs after intense exercise — such as heavy weight lifting or after a muscle tear. “A dose of 1g alcohol per kg body weight negatively effects recovery from this (muscle) damage/injury,” says Matt Barnes, Ph.D. of the Institute of Food, Nutrition, and Human Health, Massey University, New Zealand. “However, a lower dose of 0.5g per kg body weight does not. In our study, alcohol was consumed within two hours of the damaging exercise, so I am unsure how waiting longer before drinking will impact recovery.”

Although a few after-dinner drinks may not affect performance, says Barnes, alcohol does cause dehydration and can affect fine motor coordination the next day.   

Standard Drink Comparison Chart

12 oz. of beer (5% alcohol by volume)13 grams carbohydrate144 calories
5 oz. table wine (12% alcohol by volume)3-5 grams carbohydrate100 calories
1.5 oz. brandy (40% alcohol by volume)0 grams carbohydrate96 calories
NOTE: Alcohol has seven calories/gram, but these calories cannot be stored as glycogen.

Caffeine Comparison Chart

12 oz. 7-Up0 mg caffeine
12 oz. Coca-Cola Zero35 mg
8 oz. coffee, brewed108 mg
16 oz. Rockstar Zero Carb240 mg
12 oz. Starbucks tall coffee260 mg

About the author
Donna Marlor is a Registered Dietitian, Registered Nurse, and has a Master’s degree in Education Psychology. She lives and plays in Marquette, MI and maintains a private practice in Sports Nutrition. Her philosophy is, “A good diet can change your life. Start today.”