By Dr. Mercola
Many people experience a slump in energy levels by the time the afternoon rolls around. A number of factors may contribute to this phenomenon. The most common cause is post-lunch hypoglycemia, which is related to your inability to burn fat.
Hence, addressing your diet is key if afternoon fatigue is something you contend with on a regular basis. Besides alterations in your diet, intermittent fasting is one of the most effective ways to switch your body from burning carbs to burning fat, thereby boosting your mental and physical stamina.
Other factors are related to when and how much you exercise. Poor sleep also plays a role, of course, and recent research highlights the interconnectedness between sleep and exercise.
Diet Is Key for Maintaining Your Energy Levels
There are two fuels your body can use, sugar and fat. The sad reality is that our ancestors were adapted to using fat as their primary fuel and over 99 percent of us are now adapted to using sugar or glucose as our number one fuel source.
Because most are primarily burning carbs as fuel, afternoon fatigue is typically related to post-lunch hypoglycemia. By switching your body from using carbs as its primary fuel to burning fats instead, or becoming "fat adapted," you virtually eliminate such drops in energy levels. Overall, being adapted to burning fat instead of carbs has a number of benefits, including:
- Having plenty of accessible energy on hand, as you effectively burn stored fat for energy throughout the day. One way to tell if you're fat adapted or not is to take note of how you feel when you skip a meal. If you can skip meals without getting ravenous and cranky (or craving carbs), you're likely fat-adapted.
- Improved insulin and leptin sensitivity and decreased risk of virtually every known chronic degenerative disease.
- Effectively burn dietary fat for your energy, which leads to less dietary fat being stored in your adipose tissue—hence the weight loss benefits associated with fat adaptation.
- Being able to rely more on fat for energy during exertion, sparing glycogen for when you really need it. This can improve athletic performance, and helps burn more body fat. As explained by Mark Sisson, author of The Primal Blueprint, if you can handle exercising without having to carb-load, you're probably fat-adapted. If you can work out effectively in a fasted state, you're definitely fat-adapted.
First, Replace Carbs with Healthful Fats
Keep in mind that when we're talking about harmful carbs, we're only referring to grains and sugars, NOT vegetable carbs. You need very little if any of the former, and plenty of the latter. In fact, when you cut out sugar and grains, you need to radically increase the amount of vegetables you eat since, by volume, the grains you need to trade out are denser than vegetables. You also need to dramatically increase healthful fats, which include:
Olives and olive oil (for cold dishes)
||Coconuts, and coconut oil (for all types of cooking and baking)
||Butter made from raw grass-fed organic milk
|Raw nuts, such as almonds or pecans
||Organic pastured egg yolks
||Unheated organic nut oils
Avoid highly processed and genetically engineered omega-6 oils like corn, canola and soy as they will upset your omega 6/3 ratio. Trans fats should also be avoided, but contrary to popular advice, saturated fats are a key component of a healthy diet. A reasonable goal will be to have as much as 50-70 percent of daily calories from healthy fat, which will radically reduce your carbohydrate intake.
Fat is far more satiating than carbs, so if you have cut down on carbs and still feel ravenous, it's a sign that you have not replaced them with sufficient amounts of healthy fat. Most people will likely notice massive improvement in their health and overall energy levels by following this approach. To help you get started on the right track, review my Nutritional Plan, which guides you through these dietary changes one step at a time.
How Intermittent Fasting Can Help
Once you've addressed your diet, you can try intermittent fasting. This will effectively help shift your body from carb- to fat-burning mode. Please do not embark on a fasting regimen if you're still subsisting primarily on processed foods and fast food meals, however. Since it involves skipping meals, making sure you're getting high quality nutrients with each meal you do eat becomes all the more critical.
Intermittent fasting involves timing your meals to allow for regular periods of fasting. It takes about six to eight hours for your body to metabolize your glycogen stores and after that you start to shift to burning fat. If you keep replenishing your glycogen by eating every eight hours (or sooner), you make it far more difficult for your body to use your fat stores as fuel. Remember, your ancient ancestors never had access to a 24/7 supply of food like virtually all of us do with modern supermarkets. By necessity they regularly engaged in periods of fasting as they had no choice.
While there are several different intermittent fasting regimens, one of the easiest to implement simply involves restricting your daily eating to a narrower window of time, say 6-8 hours, instead of grazing all day long. This equates to 16-18 hours' worth of fasting each and every day—enough to get your body to shift into fat-burning mode. Once you have made the shift to burning fat as your primary fuel, you will be shocked at how your cravings for sugar and junk food virtually disappear.
As a precautionary note, if you're hypoglycemic, diabetic, have adrenal fatigue or pregnant (and/or breastfeeding), you are better off avoiding any type of fasting or timed meal schedule until you've normalized your blood glucose and insulin levels, or weaned your baby. Other categories of people that would be best served to avoid fasting include those living with chronic stress and those with cortisol dysregulation.
Intermittent fasting also works synergistically with high-intensity interval training (HIIT), which is a foundational part of my comprehensive exercise recommendations. The combination of fasting and exercising maximizes the impact of cellular factors and catalysts (cyclic AMP and AMP Kinases), which force the breakdown of both fat and glycogen for energy.
Fighting Fatigue with Exercise
The issue of afternoon fatigue was recently covered in a Wall Street Journal1 article, which placed the focus on exercise. Personally, I believe that altering your diet and implementing intermittent fasting will have a far greater impact than making alterations to your exercise schedule alone. But, that said, some of the advice given may be helpful in conjunction with your dietary changes. As reported in the featured article:
"Researchers and fitness trainers say whether you exercise in the morning, afternoon or evening, small changes in your routine can keep you from suffering midday blahs.
Midday is the ideal time to exercise, some fitness experts say. A workout then can give you an energy boost lasting three to four hours... If you prefer working out in the evenings, it's best to avoid exercising two to three hours before bedtime to avoid sleep disruption... On the other hand, if you are a morning exerciser and not getting seven to nine hours of sleep, Lona Sandon, a Dallas fitness instructor and assistant clinical nutrition professor at the University of Texas Southwestern Medical Center, suggests getting to bed earlier or exercising in the evening.
To avoid midday fatigue and preserve energy throughout the day, most trainers recommend doing more moderate workouts, meaning those in which you hit 70% to 80% of your target heart rate. "Listen to what your body is telling you," says Ms. Sandon. "If you have a high-stress work environment then vigorous workouts may not make you feel better. You might be better off with restorative yoga so your brain can slow down." An ideal schedule would be two to three high-intensity workouts during the week, mixed in with lighter workouts like yoga, walking or weight training, say fitness experts."
The Importance of Non-Exercise Movement During Your Workday
Sitting for prolonged periods of time can also be a source of fatigue. Besides that, compelling research shows that prolonged sitting in and of itself is a major contributing factor to chronic disease and reduced lifespan—even if you exercise regularly.
To counteract the adverse health effects of sitting, which go far beyond mere fatigue, make it a point to stand up every 10 minutes or so. As explained by Dr. Joan Vernikos, former director of NASA's Life Sciences Division and author of Sitting Kills, Moving Heals, the reason for these ill effects are due to the fact that when you sit, you're not interacting with gravity.
Based on her groundbreaking research, we now know that the key is in how many times you interact with gravity, such as standing up from your seated position, in any given day. The act of standing up makes your body interact with the forces of gravity, which is what produces beneficial health effects. Interestingly, the lipoprotein lipase is dramatically reduced during inactivity, and increases with activity, the most effective activity being standing up from a seated position. Lipoprotein lipase is an enzyme that attaches to fat in your bloodstream and transports it into your muscles to be used as fuel. So essentially, simply by standing up, you are also actively helping your body to burn fat for fuel.
After reading Dr. Vernikos's book, Sitting Kills, Moving Heals, and interviewing her, I was inspired to give some serious attention to this because even though I perform a lot of structured exercise, including high intensity interval training, I too was guilty of sitting down a vast majority of the rest of the day.
I simply set a timer on my computer to go off every 10 minutes, at which point I rise from my chair and do four jump squats. As explained by Dr. Vernikos, squatting is an extension of standing. If you squat and stand, you can get the maximum benefit of working against the force of gravity. Moving every 10 minutes or so will also get your blood pumping to oxygenate your cells, which will also combat fatigue. I mix it up though and try to do six to eight different moves every 10 minutes. The ones I currently use are one legged squats, two legged squats, lunges, jump squats, hamstring stretches and pectoral doorway stretches.
An Obvious Culprit: Poor Sleep...
Not to be ignored of course is sleep. If you're not sleeping well, it will be next to impossible to avoid lagging energy levels. According to recent research, maintaining a regular exercise program can help improve your sleep over time2. It can also boost your cognitive performance, as evidenced by a number of studies3. In one recent study evaluating the effect of exercise on sleep,4 volunteers with sleep complaints took two-hour forest-walks to assess how it affected their sleep patterns. According to the authors:
"Two hours of forest walking improved sleep characteristics; impacting actual sleep time, immobile minutes, self-rated depth of sleep, and sleep quality... Furthermore, extension of sleep duration was greater after an afternoon walk compared to a forenoon walk."
In another study5, the results suggested that improved sleep had a beneficial influence on exercise performance the next day, rather than the exercise influencing sleep. Over time, however, exercise will tend to improve your sleep patterns, even if you're struggling with more serious sleep problems. As reported by Yahoo News6:
"While prior research has shown that for most people, exercising can improve sleep, for insomniacs the relationship may be a bit more convoluted, the new evidence suggests. The rationale? Head researcher Baron told the New York Times that people with insomnia tend to be 'neurologically different' and have a 'hyper-arousal of the stress system.' Breaking a sweat in the gym one day isn't likely to override the system, she said, and could even exacerbate it.
Still, if you struggle with insomnia and currently don't exercise, Baron said that it's advisable to start -- but don't expect miracles. The process could take months, which can be frustrating for someone suffering from sleep deprivation. 'If you have insomnia you won't exercise yourself into sleep right away,' she said in a press release. 'It's a long-term relationship. You have to keep at it and not get discouraged.'"
Some Sleep Basics
That said, it seems clear that you can help set up a positive feedback loop where both your sleep and exercise benefits. Two key points to remember if you're having difficulty sleeping include the following. For more tips, please see my article 33 Steps to a Good Night's Sleep.
- Create a sleep sanctuary. This means removing items associated with entertainment, recreation, work and hobbies, and turning your bedroom into a single-purpose space—one for sleeping. Of utmost importance: Make sure your bedroom is cool, dark and quiet. These three factors can have a major impact on your sleep. In regards to temperature, studies show that the optimal room temperature for sleep is quite cool, between 60 to 68 degrees Fahrenheit, so keep the temperature in your bedroom no higher than 70 degrees.
As for light, even the tiniest bit of light in the room can disrupt your internal clock and your pineal gland's production of melatonin and serotonin, hormones involved in your body's circadian rhythm of sleep and wakefulness. So close your bedroom door, get rid of night-lights, and most importantly, cover your windows. I recommend using blackout shades or heavy, opaque drapes. Also cover up your clock if it has a lit display. Alternatively, you could wear an eye mask to block out any stray light.
- Turn off your gadgets well before bedtime. Again, the artificial glow from your TV, iPad, computer or smartphone can serve as a stimulus for keeping you awake well past your bedtime by disrupting melatonin production. I recommend turning off all electronic gadgets at least one hour before bed. As Rothstein suggests, that time is far better spent reading a good old fashioned book, practicing relaxation techniques or meditating.
Banish Afternoon Fatigue with Appropriate Diet and Lifestyle Changes
So remember, if you're frequently battling with afternoon fatigue, check your lunch selections, first of all. More often than not, you'll find that the more carb-heavy your lunch, the more apt you are to feel tired an hour or two later. To remedy the situation, focus on shifting your diet from carbs to healthful fats. Once your diet has been addressed, implementing intermittent fasting is an effective strategy for really shifting your body into fat-burning mode.
Just remember that proper nutrition becomes even MORE important when fasting, so I believe that addressing your diet is your first step. Always listen to your body, and go slowly ; work your way up to 16-18 hour fasts if your normal schedule has included multiple meals a day. Also be sure to address any hypoglycemic tendencies, such as headaches, weakness, tremors or irritability, as it can get increasingly dangerous the longer you go without eating to level out your blood sugar.
Once you're fat adapted, your energy levels will remain fairly stable throughout the entire day, and you hunger cravings will virtually disappear. Exercise and sleep are also important factors, so experiment with your workout schedule to see what works best for you. Again, proper sleep can boost your exercise performance, and exercise in turn can help improve your sleep, forming a positive feedback loop.