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obesity disrupts dopamine function

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  • Obesity is just one side effect of insufficient movement. The scientific literature has linked inactivity to a whole host of diseases and ailments, raising your risk of general ill health by 114 percent
  • Which comes first — obesity or sedentary behavior? Recent research suggests obesity dampens dopamine signaling in your brain, which suppresses your body’s natural impulse to stay active
  • Researchers have found there is also a genetic component to your dislike of exercise that may be overcome through a well-planned regimen that accounts for your aerobic capacity and physical ability
 

Which Comes First — Obesity or Sedentary Behavior?

January 13, 2017 | 157,706 views
| Available in EspañolDisponible en Español

By Dr. Mercola

The dangers of inactivity have become increasingly well-recognized. Obesity is just one side effect of insufficient movement. The scientific literature has linked inactivity to a whole host of diseases and ailments.1,2

For example, physical inactivity raises your risk of general ill health by 114 percent, your risk of Alzheimer's disease by 82 percent, and your risk of depression by 150 percent. Overall, chronic inactivity has a mortality rate similar to smoking.3

But which actually comes first — obesity or sedentary behavior? Recent research suggests that obesity actually alters your brain function, thereby suppressing your body's natural impulse to stay active.

As noted by senior author Alexxai V. Kravitz, Ph.D., an investigator in the Diabetes, Endocrinology and Obesity Branch at the National Institute of Diabetes and Digestive and Kidney Diseases:4

"There's a common belief that obese animals don't move as much because carrying extra body weight is physically disabling. But our findings suggest that assumption doesn't explain the whole story.

Other studies have connected dopamine signaling defects to obesity, but most of them have looked at reward processing — how animals feel when they eat different foods.

We looked at something simpler: dopamine is critical for movement, and obesity is associated with a lack of movement. Can problems with dopamine signaling alone explain the inactivity?...

In many cases, willpower is invoked as a way to modify behavior. But if we don't understand the underlying physical basis for that behavior, it's difficult to say that willpower alone can solve it."

The Biological Imperative of Movement

Previous research has shown that humans regulate their physical movement quite naturally. There appears to be "biological imperatives to movement" built into our system.

One such study5 found that not only do people tend to move and rest in logical intervals, physical activity also appears to affect your body's internal clock mechanisms and circadian rhythms.

The intervals of movement and inactivity were more consistent in younger people than older ones. As noted by The New York Times:6

"In essence, the young people's bodies seemed to be somehow remembering and responding to what that body had just been doing, whether sitting or moving, and then calculating a new, appropriate response — moving or sitting.

In doing so, the researchers felt, the body created a healthy, dynamic circadian pattern."

Another study,7 this one looking at the movement of mice, also concluded that exercise plays a role in maintaining a healthy circadian rhythm, allowing the animals to maintain more natural activity patterns. Without exercise, the animals' activity levels became more random.

Obesity Disrupts Dopamine Function

Most recently, Kravitz's team came to the conclusion that carrying excess weight may in fact dampen the motivation to move by way of disrupted dopamine signaling, thereby creating a negative spiral of sedentary behavior and added weight.8,9 As reported by the LA Times:10

"Many other powerful factors influence our inclination to exercise — not least having the safe spaces, leisure time and social encouragement to do so.

But new research in mice confirms that obesity disrupts the proper functioning of a key docking station for dopamine, a brain chemical that affects our moods, appetites and motor control."

When mice were fattened up, they noticed a decrease in activity of a specific class of dopamine receptors (dopamine D2) in the brain's striatum. This area of the brain controls physical movement and reward-seeking behavior.

As a result, the obese mice became what we would call "couch potatoes." According to the authors, this D2 dopamine receptor deficit was "sufficient to explain the lack of activity" in obese mice.

Improving Dopamine Receptor Function May Be Key to Boosting Exercise Motivation

To verify the results, the researchers used lean mice genetically engineered to have defective D2 dopamine receptors. The fact that these mice did not readily develop obesity when fed high-fat chow, despite their inactivity, suggests the D2 dopamine receptor indeed plays a crucial role in the equation.

Taking it another step, when the researchers activated the dopamine receptor activity in the obese mice, they automatically increased their physical activity. As noted in the featured article:

"The new research … suggests that inactivity is not a natural CAUSE of obesity. The activity of the affected dopamine receptor varies considerably among mice and presumably in humans, and it's clearly not the case that the lazy among us all get fat.

Rather, inactivity appears to be a downstream CONSEQUENCE of excess weight … The research also suggests that carrying excess weight may subtly interfere with the rewards we are meant to get from physical activity."

The team is now planning to investigate how diets affect dopamine signaling, and the rate at which normal dopamine activity can be recovered with dietary changes and weight loss.

That said, obesity is not the only factor that can impact your dopamine signaling. Your genetic makeup may also predispose you to be more or less active, as certain genes modulate dopamine production in your brain.

Your Activity Level May Be Genetically Encoded

Here, researchers initially evaluated lab rats that were selectively bred to be fit and active animals or unfit and inactive. Once they found differences in dopamine activity between these two cohorts, they recruited 3,000 human participants for a clinical trial. The video above describes how dopamine works in your brain. Rodney Dishman, Ph.D., a professor of exercise science at the University of Georgia and lead author of the study, said:11

 "Our current field trial with humans suggests that variations in genes that encode for dopamine and other neurotransmitters linked with physical activity account for low or high physical activity directly. These genes also act indirectly, by their associations with people's acquired motivation to be active and also with select personality traits."

Dr. Keri Peterson, internist with Lenox Hill Hospital in New York added:

"Dopamine is a chemical in our brains that plays a role in feeling pleasure and regulating drive. The inherited activity of these genes may cause us to seek physical activity or to choose a more sedentary lifestyle. This preliminary report suggests that the motivation and desire to exercise is hard-wired. You may actually have your parents to blame for being a couch potato."

Understanding the Role of Dopamine

If faulty dopamine signaling is responsible for inactivity, or the loss of the natural inclination to stay active, could natural dopamine boosters correct the problem? The answer to that still remains to be seen, but I imagine it could potentially be useful. Dopamine is involved in reward-seeking behavior. The release of dopamine triggers a surge of pleasurable feelings and energy, motivating you to seek out more of the same.

Your brain can secrete dopamine simply by looking at a picture of a loved one or a beautiful sunset. Downregulation of dopamine also plays a role in addictive behavior. When you overindulge in dopamine stimulators — be it cocaine, sugar, alcohol or sex, just to name a few — your brain's reward center compensates by decreasing your sense of pleasure and reward.

It does this by downregulating your D2 receptors, basically eliminating some of them. When that happens, you no longer feel the same pleasure and reward. You've basically developed a tolerance, which means you want more and more of your fix but never achieve the same "high" you once had. All the while, the addictive cravings grow stronger.

On the other hand, without sufficient amounts of dopamine your motivation drops, leaving you unable to experience pleasure. So, while addiction is at one end of the dopamine spectrum, depression and "the blues" is on the other. The key is to find a healthy balance.

Natural Dopamine Boosters

The following strategies and supplements have been shown to increase and/or balance dopamine function, thereby helping to improve symptoms of depression such as fatigue, loss of interest in life, poor memory and impulsive behaviors.12,13

Use only ONE dopamine supplement at any given time, as excessive amounts of dopamine may trigger anxiety and other adverse effects. Also, do not take dopamine supplements if you're pregnant, lactating or take methyldopa, antidepressants or antipsychotic drugs. If you're on medication, be sure to consult with your physician before adding these kinds of supplements.

Cold thermogenesis: This is an especially easy strategy to use this time of year — simply expose yourself regularly to cold. This has been well documented to increase dopamine levels. I personally do a cold water swim nearly every morning in my pool after my 30-minute full spectrum infrared sauna. The temperature of the water this time of year ranges from low to high 60s.

L-tyrosine: This is a precursor of dopamine available in foods such as meat, eggs and fish, and in supplemental form. If using a supplement, start out with a dose of 500 milligrams (mg). Monitor yourself for 30 minutes. If you feel a slight improvement, this dose is likely sufficient.

If you sense no change, take another 500 mg dose and monitor yourself for another 30 minutes. You may take up to 1,500 mg two to three times per day. Side effects include agitation and increased blood pressure. Decrease the dose you take should either of these occur.

Contraindications: Avoid L-tyrosine if you're pregnant or lactating. It also may interact with certain nutritional supplements, including St. John's Wort, 5-HTP, tryptophan and SAMe. Consult with a knowledgeable health care practitioner before combining these supplements.

Macuna pruriens: Studies suggest macuna supplements may be helpful for conditions related to dopamine deficiency, such as depression and stress. Extracts have been shown to increase dopamine concentrations, along with other mood-related neurotransmitters such as serotonin and norepinephrine. University Health News14 suggests using macuna extracts standardized to contain 15 percent L-dopa, and taking 300 mg twice per day.

Contraindications: Avoid macuna pruriens if you're pregnant or lactating. It also may interact with certain nutritional supplements, including St. John's Wort, 5-HTP, tryptophan and SAMe. Consult with a knowledgeable health care practitioner before combining these supplements.

L-theanine: An amino acid found in green and black tea, L-theanine has the ability to cross the blood-brain barrier to increase brain levels of dopamine, serotonin and GABA. Studies show it has antidepressant,15 stress-relieving and anti-anxiety effects, and may improve memory and mental focus.16 A suggested dose is 200 mg two to three times a day.

Rhodiola rosea root: This plant has a long history of use in Asian and Eastern European traditional medicine. It is typically used to treat depression, relieve fatigue and enhance mental performance. It works in part by stabilizing dopamine levels and supporting dopamine reuptake, and by decreasing the cortisol (a primary stress hormone) response, thereby reducing symptoms of depression, anxiety and stress-related fatigue.17

Look for a rhodiola rosea root extract standardized to contain 3 percent rosavins and at least 1 percent salidrosides. Suggested dosage is 170 mg twice per day.

B vitamins and animal-based omega-3: These nutrients also support healthy dopamine levels.18

Exercise Motivation Beyond the Dopamine Connection

Scientists have also found other factors that drive people to become physically active and enjoy the process. The dopamine connection discussed above is one factor. How you interpret your body reactions to exercise is another. Researchers at Iowa State University have found that your capacity for exercise may actually be lower than you think, and this could affect your motivation to keep going once you start.

According to professor Panteleimon Ekkekakis, Ph.D., 50 percent of people who start a new exercise program will stop within the first six months. Although there are likely many factors involved, Ekkekakis believes many new to exercise are unable to accurately monitor and regulate the intensity of their program, and this could have a dampening effect on their motivation.19

Without experience, overestimating intensity may reduce efficiency of the program and lead to negative affective responses and/or injuries. Both of these factors may increase the dropout rate of people new to exercising. Importantly, Ekkekakis found the ability to self-regulate during exercise deteriorates as the exercise intensifies to a point that exceeds your body's ability to exchange gasses.

This ventilatory threshold is also the point at which optimal fitness benefits are developed in people who have practiced a sedentary lifestyle. Without the ability to recognize and regulate exercise intensity, you may push past your limits without realizing it. Essentially, you have a physical capacity beyond which your body is unable to function. This limitation is based on lung capacity, oxygen transport and how quickly oxygen is absorbed and used in muscle tissue.

Avoid Exceeding Your Ventilator Threshold

Ekkekakis suggests that for the average person, this ventilator threshold is approximately 50 percent of their maximum ventilation capacity.20 Elite athletes may enjoy a threshold as high as 80 percent of their maximum capacity, while those who have lived a sedentary lifestyle may experience a threshold at 35 percent. If you try to exercise too quickly or intensely you'll likely begin to hate the activity and stop.

For some people who have been sedentary much of their life, just a short walk after dinner, cooking dinner or doing the dishes may stress your body to your ventilator threshold. So, the key to maintaining an exercise program long-term may lie in avoiding overexertion too early in the game. In other words, practice patience and increase your activity at a slower pace. The good news is this threshold is not static, and will improve with the right exercise.

Rewire Your Brain to Enjoy Exercise

To help you build an exercise habit that will last a lifetime, look for an activity you really enjoy and then team up with others who provide you with social interaction during your workout and reward and motivation to continue the process. As noted by Dishman:21

"If you haven't found something which is pleasurable, either the activity or the people you're doing it with, then you don't have much reason to continue it. When people start viewing exercise as a duty or obligation, then that's not a formula for sustained activity. That just puts people in a constant state of dissatisfaction."

Variety Is the Spice of Life

When developing your exercise plan, variety is the name of the game. The following five types of exercises will turn your fitness routine into a truly comprehensive exercise plan. Just remember that non-exercise movement is just as important — if not more so — as a regimented fitness routine. Standing up and walking whenever possible, throughout each day, can go a long way toward warding off chronic disease.

Interval (anaerobic) training: This really is aerobic and anaerobic, but the research shows that the anaerobic phase is far more important. The best way to condition your heart and burn fat is not to jog or walk steadily for an hour. Instead, it's to alternate short bursts of high-intensity intervals with gentle recovery periods. This type of exercise, known as HIIT, can dramatically improve your cardiovascular fitness and fat-burning capabilities.

Another major benefit of this approach is that it radically decreases the amount of time you spend exercising while giving you even more benefits. For example, intermittent sprinting produces high levels of chemical compounds called catecholamines, which allow more fat to be burned.

The resulting increase in fat oxidation increases weight loss. So, short bursts of activity done at a very high intensity can help you reach your optimal weight and level of fitness, in a shorter amount of time. It also promotes the production of human growth hormone (HGH), known as "the fitness hormone," which can help you add youthful vigor to your years, in addition to promoting weight loss and improved muscle building.

Aerobic: Jogging, using an elliptical machine and walking fast are all examples of aerobic exercise, which will increase the amount of oxygen in your blood and increase endorphins, which act as natural painkillers. Aerobic exercise also activates your immune system, helps your heart pump blood more efficiently and increases your stamina over time.

Just don't make the mistake of using aerobics as your primary or only form of exercise, as you'll miss out on many of the most potent health benefits exercise has to offer.

Strength training: Rounding out your exercise program with a one-set strength training routine will ensure that you're really optimizing the possible health benefits of a regular exercise program. You need enough repetitions to exhaust your muscles.

The weight should be heavy enough that this can be done in fewer than 12 repetitions, yet light enough to do a minimum of four repetitions. Avoid exercising the same muscle groups every day. They need at least two days of rest to recover, repair and rebuild.

Core exercises: Pilates and yoga are great for strengthening your core muscles, as are specific exercises you can learn from a personal trainer. Even if you aren't using a personal trainer right now, please watch these sample videos for examples of healthy exercise routines you can do with very little equipment and in virtually any location. Focusing on your breath and mindfulness along with increasing your flexibility is an important element of total fitness.

Stretching: This is another important piece of the puzzle, and yet overlooked by many in their exercise programs. The right stretches may help heal lower back pain, prevent injuries and improve your ability to move throughout your day. You can read more about stretching and see a sample video in my previous article, "When and How Should You Warm Up, Stretch, Exercise and Cool Down?"

To Lose Weight and Maximize Fitness Benefits, You Must Address Your Diet

Last, but certainly not least, I must remind you that carrying excess weight is ultimately a problem rooted in less than optimal food choices, NOT lack of exercise. Contrary to popular belief, you simply cannot out-exercise your mouth. If your diet is poor, you will not be able to reap the maximum benefits of your fitness efforts, and more than likely, your weight will stubbornly refuse to fall off.

Your diet may in fact account for as much as 80 percent of the benefits you reap from a healthy lifestyle, with exercise accounting for the remaining 20 percent. It's an important 20 percent, no doubt, but nutrition lays the groundwork upon which everything else is built.

It is important to make food choices that will help you regain your body's ability to burn fat as its primary fuel as I've discussed in many previous articles. Once you have achieved that and normalized your body weight, you can become far more liberal in your food choices.

Also remember that eating REAL FOOD is a vital principle in making your food choices. Doing so will help you avoid the most serious pitfalls. However, the devil is in the details, and if you're serious about optimizing your health, you'd be wise to take the time to understand some of the finer details of what makes for a healthy diet. To help you with this, I've created a detailed and comprehensive Nutrition Plan.

In addition to WHAT you eat, WHEN you eat can also make a big difference. Fasting can be enormously helpful for kick-starting weight loss, either by doing a water fast for a few days, or intermittently fasting.

Many of the metabolic problems people suffer with these days are related to the fact that they never stop eating, and the human body is designed to cycle through feasts and famines. That's when biological processes are optimized. To learn more, please see my previous article, "Peak Fasting — How Long Should You Intermittently Fast?"