By Dr. Mercola
One of the biggest hurdles people face in maintaining an exercise program is finding the time to do it. Fortunately, modern exercise research shows that you can significantly reduce your workout time while reaping better health benefits, compared to a traditional cardio program.
The key is Peak Fitness or high-intensity interval training (HIIT), which also goes by other terms such as anaerobic, or burst training, which I've discussed on numerous occasions over the past couple of years.
However, recent research throws yet another twist into the discussion about exercise intensity, time, and subsequent effects.
Danish researchers were quite surprised when they realized that exercising for less amount of time (even without using high-intensity type training) still produced greater weight loss, without making any planned dietary changes.1
According to the old adage, the more calories you expend during exercise, the more weight you should lose. But for many, this theory never seemed to hold true, as they continue to struggle with their weight despite spending several hours a week at the gym.
We now know using HIIT can give you better results in 40-60 minutes a week compared to 5 hours of conventional aerobics. But here, the major surprise was that 30 minutes of exercise beat out 60 minutes of exercise at the same weekly frequency, in terms of weight loss!
Finding Your Goldilock's Exercise Zone
The evidence suggests there may be a type of "Goldilock's Zone" when it comes to exercise. "Just enough" exercise boosts your overall energy levels, spurring you to be more active during non-exercising hours (taking stairs, getting out of your office chair more frequently, walking longer distances).
"Too much" exercise might actually lead to an increasingly sedentary lifestyle outside of exercise hours, most likely due to a combination of exhaustion and inadvertently eating or snacking more to compensate for the high calorie expenditure during exercise. ("Too little" or "none" will obviously not do you any good at all.)
You may recall I recently wrote about a study that concluded exercising in the morning did not lead to increased food intake or food cravings, which seems to be in direct contradiction to the findings in today's featured study. But let's keep in mind that "the devil is in the details."
In the current study, mildly overweight men who exercised at a moderate pace for about 30 minutes (until they'd burned 300 calories based on their individual metabolic rate) experienced a boost in energy and overall activity levels, and did not increase their food intake. Obese women who exercised at moderate to intense pace for 45 minutes in the morning were also found to be more energetic and active during non-exercising hours, and did not subsequently increase their food intake either.
The men who sweat it out for 60 minutes instead of 30, however, did not increase overall activity levels during non-exercise hours, and they ended up eating more. As reported by the New York Times:2
"At the end of the 13 weeks, the members of the [non-exercising] control group weighed the same as they had at the start, and their body fat percentages were unchanged, which is hardly surprising.
On the other hand, the men who had exercised the most, working out for 60 minutes a day, had managed to drop some flab, losing an average of five pounds each. The scientists calculated that that weight loss, while by no means negligible, was still about 20 percent less than would have been expected given the number of calories the men were expending each day during exercise, if food intake and other aspects of their life had held steady.
Meanwhile, the volunteers who'd worked out for only 30 minutes a day did considerably better, shedding about seven pounds each, a total that, given the smaller number of calories that they were burning during exercise, represents a hefty 83 percent 'bonus' beyond what would have been expected..." [Emphasis mine]
Finding Your Sweet Spot Includes Knowing Which Foods to Eat and Which to Avoid
In summary, the researchers concluded that the shorter exercise session appears to have allowed the men to "burn calories without wanting to replace them." Combined with greater activity levels at work and off-hours, the overall health effect generated was greater than in those whose workout sessions were longer, simply because the latter didn't experience the same boost in off-hour energy levels, and ended up eating more.
But another important factor not touched on in this research is the effect of the types of food you eat, before and after exercise. The study participants were not given any particular diet; they were simply asked to not alter their normal fare.
It's well worth noting that your choice of breakfast food may play a significant role in decreasing or heightening sensations of hunger afterward, which will affect your overall calorie intake for the day – not to mention how foods can alter your metabolic functioning, and either for the benefit or detriment to your weight loss.
For example, eating carbohydrates for breakfast will inhibit your sympathetic nervous system (SNS) and reduce the fat burning effect of your exercise. Instead, it activates your parasympathetic nervous system (PSNS), which promotes storage of fat – the complete opposite of what you're aiming for. Avoiding fructose and other grain carbohydrates is a critical element of a successful weight loss strategy. This includes sports or energy drinks and fruit juices (even if they're freshly squeezed).
Additionally, it would be wise to consider skipping breakfast. You can review the article I recently wrote on this here. This is a form of intermittent fasting and I believe it is one of the most profound new developments in weight loss management. This can radically improve your ability to shift to fat burning mode and effectively burn fat rather than glucose. Also, when you exercise in a fasted state you tend to have your cells rebuild and repair or get younger.
Diet Also Affects HGH Production if You Do Interval Training
Furthermore, if you're doing high intensity interval training you will naturally boost your production of human growth hormone (HGH) – a fat-burning, muscle-boosting hormone – but if you consume fructose within two hours of exercise, you will effectively negate this highly beneficial effect. In essence, if you don't pay attention to your diet, you may be wasting an awful lot of time in the gym.
As explained by HGH Magazine:3
"A high sugar meal after working out, or even a recovery drink (containing high sugar) after working out, will stop the benefits of exercise induced HGH. You can work out for hours, then eat a high sugar candy bar or have a high sugar energy drink, and this will shut down the synergistic benefits of HGH.
...If you miss reaching HGH release during working out, you will still receive the calorie burning benefit from the workout. However, you'll miss the HGH 'synergy bonus' of enhanced fat burning for two hours after working out.
This is an extremely important fact to remember if you want to cut body fat and shed a few pounds. ...[Research has] demonstrated that carbohydrates are burned during exercise in direct proportion to the intensity of training. Fat burning is also correlated with intensity. However, the actual fat burning takes place after the workout, during the recovery. This makes the 'Synergy Window,' the 2 hour period after a workout, very important in maximizing HGH, once it's released during exercise."
Another 2010 study in the Journal of Applied Physiology4 showed that eating a low-carbohydrate meal after aerobic exercise enhances your insulin sensitivity. This of course is highly beneficial, since impaired insulin sensitivity, or insulin resistance, is the underlying cause of type 2 diabetes and a significant risk factor for other chronic diseases, such as heart disease.
So, while exercise is very effective for enhancing insulin sensitivity, the type of foods you eat plays a significant supporting role. Eating a high sugar meal after exercise will simply not allow you to reap the maximum benefits from your workout, regardless of what type of exercise you engage in.
Good, Better, Best
As you can see, optimizing your health and weight involves a number of factors, and all of them need to be given appropriate consideration. Poor diet with a strenuous exercise regimen will surely leave you disappointed, just as a healthy diet with improper or no exercise will leave most people wanting. It's worth noting though that about 80 percent of the health benefits you get from a healthy lifestyle come from your diet. The remaining 20 percent is derived from your exercise – but it's an important 20 percent! It's really about synergy.
That said, abstaining from food altogether for certain periods of time, known as intermittent fasting, can actually boost exercise results even more.
I've previously interviewed fitness expert Ori Hofmekler on the issue of fasting and exercise. According to Ori, fasting actually has the surprising benefit of helping you reconstruct your muscles when combined with exercise. This is due to an ingenious preservation mechanism that protects your active muscle from wasting itself.
In a nutshell, if you don't have sufficient fuel in your system when you exercise, your body will break down other tissues but not the active muscle, i.e. the muscle being exercised. That said, neither Ori nor I advocate starvation combined with rigorous exercise. It's important to be sensible. And you need to consume sufficient amounts of protein in order to prevent muscle wasting. While most people need to address the foods they DO eat before considering skipping meals, intermittent fasting can provide you with many benefits, and is another tool you can experiment with to help you reach your goals.
One of the mechanisms that makes intermittent fasting so effective for weight loss is the fact that it – like HIIT – provokes the secretion of HGH. It also increases catecholamines, which increases resting energy expenditure while decreasing insulin levels, which allows stored fat to be burned for fuel. Together, these and other factors will turn you into an effective fat-burning machine – especially if you incorporate it with high intensity interval training.
How to Safely Combine Intermittent Fasting with Exercise to Boost Weight Loss
In essence this fitness-enhancing strategy looks at the timing of meals, as well as when NOT to eat. This isn't one of those fad plans, where you eat just one or two things for several days in a row. Instead, intermittent fasting simply means restricting your food intake during the day to a smaller time window (typically six to eight hours). If that's still too difficult, restrict your food choices to light raw foods, vegetable juice and/or whey protein or eggs, but aim for having just one main meal a day, in the evening.
When you add exercise to the mix, you complete your workout while fasting, but this must be followed by a recovery meal within 30 minutes of your workout. The easiest way to do this is to exercise in the morning on an empty stomach, followed by a recovery meal half an hour later. Then you fast until the set time window designated for eating, followed again with fasting during late-evening/overnight hours and into the morning, until 30 minutes after exercise the next day.
Naturally, if it's a non exercise day, you don't need the recovery meal. But on exercise days, a recovery meal is critical and should NOT be skipped in the name of fasting. Whey protein is ideal, as it is fast-assimilating and will provide you with the nutrients your muscles need for recovery. (Make sure to avoid all sources of fructose for the reasons discussed earlier). Skipping the recovery meal after exercise is very ill advised, as it can lead to brain and muscle damage.
Why Exercise and Fasting Makes for a Beneficial Duo
Exercise while in a fasted state results in acute oxidative stress, and while this may sound ominous it actually benefits your muscle by keeping your muscles' mitochondria, neuro-motors and fibers intact. Chronic oxidative stress, on the other hand, is very detrimental and can lead to disease. As explained by fitness expert Ori Hofmekler:
"[Acute oxidative stress] is essential for keeping your muscle machinery tuned. Technically, acute oxidative stress makes your muscle increasingly resilient to oxidative stress; it stimulates glutathione and SOD production in your mitochondria along with increased muscular capacity to utilize energy, generate force and resist fatigue.
Hence, exercise and fasting help counteract all the main determinants of muscle aging. But there is something else about exercise and fasting. When combined, they trigger a mechanism that recycles and rejuvenates your brain and muscle tissues."
The mechanism he refers to is triggering genes and growth factors, including brain-derived neurotropic factor (BDNF) and muscle regulatory factors (MRFs), which signal brain stem cells and muscle satellite cells to convert into new neurons and new muscle cells, respectively. This means that exercise while fasting may actually help to keep your brain, neuro-motors and muscle fibers biologically young. The combined effect of both intermittent fasting and short intense exercise may go way beyond helping you to burn more fat and lose weight; it may help you to:
Turn back the biological clock in your muscle and brain Boost growth hormone Improve body composition Boost cognitive function Boost testosterone Prevent depression
Cut the Correct Calories!
Intermittent fasting (IF) makes your dietary choices all the more important. Please do not embark on intermittent fasting if your diet consists primarily of processed and/or fast foods! This is because it's not restricting calories per se that does the trick, but rather it's the restriction of unnecessary calories from foods that do not supply essential nutrients.
It's important to realize that all calories are NOT created equal, and will not have identical effects your weight or health.
Their value depends on the types of food (nutrients) they're attached to. You barely need any grain carbohydrates in your diet. You could cut out virtually all sugar and grains, limiting carb calories to vegetables (and perhaps some less harmful starchy carbs like potatoes and rice) and still thrive. Unfortunately, in the US, six of the top 10 sources of calories are carbohydrates from sugars and grains,5 and this is a major reason why so many Americans are overweight. They're simply eating far too many sugars. So it's very important to restrict carbs when doing a calorie restrictive diet. When you cut out the sugars and carbs it is wise to replace them with high quality non-processed fats. Some of my favorites include:
- Organic grass-fed raw butter
- Coconut oil
There's very compelling evidence showing that calories from healthy fats are far more beneficial for your health than calories from carbohydrates. And fear not... It's already been well established that stearic acid (found in cocoa and animal fat) has no effect on distorting your healthy cholesterol ratios at all, and actually gets converted in your liver into the monounsaturated fat called oleic acid.
The other two, palmitic and lauric acid, do raise total cholesterol. However, since they raise "good" cholesterol as much or more than "bad" cholesterol, you're still actually lowering your risk of heart disease. And there are additional benefits. Lauric acid (as from coconut oil) has been shown to boost thyroid hormone activity along with your body's metabolic rate. This is obviously a huge advantage to those interested in weight loss or those who suffer from an underactive thyroid.
I couldn't encourage you more to implement this program. It has radically improved my personal confidence in using diet choices to achieve high level wellness and optimal body fat. Cutting down on your grains and sugars, replacing them with high quality fats and skipping some meals, especially before exercise, seem to be a powerful combination to help you take control of your health.