Is Stress Making You Fat?
by Jade Teta on February 9, 2012

How many calories does stress have? We agree this is a ridiculous question, but ask almost anyone if stress can make a person fat and you will receive a resounding yes.

But if we agree stress has no calories, and we also believe fat gain is about nothing but calories, then how in the world does stress stimulate fat gain?

The truth is the calorie model is not the whole story on fat loss. Stress and other lifestyle factors work through complicated hormonal and metabolic mechanisms that alter not only the number of calories we eat, but also where on the body we store them and most importantly which type we burn; sugar, fat, or muscle.

I realize not everyone likes to delve into the deep biochemistry that is required to truly understand how stress causes fat gain, so I will do my best to make this as simple as I can.

One thing is for certain, if you can understand the impact stress has on your physiology and how it can make you fat, a whole new way of thinking about diet, exercise, and lifestyle will open up.

A Historical Frame of Reference

Before I can even begin to talk about stress, it is important to understand what it is and how humans have adapted to deal with it. Humans have evolved on this planet for millions of years. We have had to deal with predators, food shortages, ice ages, natural disasters, rugged terrain, uncertain future, and countless other “stressful” things.

If you think you have it tough today, imagine walking down the street and having a pack of hungry wolves jump out from behind a dumpster and decide you are for dinner. Or walking into a food store where the cashier hands you a spear and points you towards the wild boar living in aisle 4.

This may seem laughable right now, but understanding the physiological reaction of that kind of stress is exactly what is needed to decipher the impact stress has on fat gain.

The bottom line is humans are designed for acute stress like running away from a hungry predator, fighting off an intruder, or catching dinner. That is because, during the millions of years we have been on the planet, we encountered these types of stress all the time.

Your physiology is hard wired to the realities of your historic ancestors. Whether you are being chased by a pack of wolves, fighting a wild boar, under a severe deadline at work, facing financial uncertainty, or stuck in traffic, your response to stress is exactly the same as far as your physiology is concerned.

The Brain Adrenal Axis

The stress response is regulated by closely orchestrated communication between the brain (your hypothalamus) the pituitary gland and your adrenal glands (two little pieces of endocrine tissue that sit on top of your kidneys). This is known in science as the HPA axis (Hypothalamic-pituitary-adrenal axis).

You can think of the brain as an army’s central command center. When it gets a warning that there is an incoming threat, it sends an immediate signal to the adrenal glands. In a fraction of a second, the adrenal glands flood the body with hormonal signals like adrenaline, noradrenaline, and cortisol whose job is to give the body the energy required to stay and fight or run like hell.

You know what this feels like. If you have ever been in a near car accident, you probably felt an intense surge of energy travel through your body that allowed you to slam on the brakes or swerve out of the way. That was your HPA axis in action.

This is where things can go wrong. In the modern-day, there is nothing to run from and there is no giant Twinkie monster you have to kill to get lunch. So instead of moving in response to stress, you just sit there with large amounts of adrenal hormones surging through your body. This is not a good thing.

The major action of adrenal hormones is to raise the amount of sugar and fat in the blood to supply the body with energy. The whole body mobilizes all at once to supply the body with everything it needs to survive. The liver is instructed to kick out stored blood sugar as well as make some extra. Muscle and fat aid the creation of new sugar through the release of amino acids from muscle and glycerol from triglyceride (fat) respectively.

In other words, stress burns fat, sugar, and muscle under normal circumstances. But when it becomes recurrent and chronic, fat is usually spared while muscle is taken.
In a normal more healthy stress response, you are able to run your way to safety or fight your way out of danger. The process of the intense movement to run away or fight is just what the body needs because that triggers the release of other hormones like testosterone and human growth hormone (HGH).

Those hormones then act to repair damaged tissue and partition energy usage towards fat metabolism while at the same time sparing and even building muscle. The repair mechanisms of these two hormones rebuild the body back leaner, faster, and stronger improving the chances that the next stressful encounter will result in another success. All of this together feeds back on the brain and the adrenals allowing them to stop the alarms and go back to a rest and recovery physiology.

Chronic Stress

The problem starts when stress, whether real or perceived, becomes constant and continuous, is not followed by intense activity, or never ends. Chronic stress is different because the stressors continually force the body to work harder and harder to compensate for the physiological disruptions.

One of the first and most important things to change is relative amounts of cortisol. Relative is an important term because it means how much cortisol do you have in relation to other hormones. The most important thing to remember here is that cortisol (one of your major stress hormones) exerts actions on the body that are beyond our awareness.

High amounts of continuous cortisol secretion induce serious changes in our physiology. Two important changes occur in relation to hunger and cravings. Excess cortisol impacts hunger and increases the urge for sweets and fatty food. A sure sign you have high-stress levels is a lack of appetite in the morning.

Two studies in Endocrinology 2004 (volume 145 #5 & #6) and another in Psychoneuroendocrinology (Volume 30 # 9), show how cortisol can decrease hunger in the short term, and increase binge eating with a desire for highly palatable foods later. In other words, cortisol makes you eat less often but makes you overeat the wrong foods when you get the chance.

This makes complete sense when you think about stress from a historic perspective. If walking out of your house could result in getting swept away by a giant Terradactyl, you would likely make fewer trips to the grocery store and seek out the most energy-dense foods that would sustain you for longer.

In other words, you would eat less frequently and avoid the danger lurking outside as much as possible. A comprehensive review by Dr. Pecoraro of UCLA San Francisco was published in 2006 in the journal Progress in Neurobiology (volume 79). In that paper, he cited research that showed this is exactly the case.

This review showed that through several overlapping mechanisms chronic stress caused animals to decrease the number of times they ate opting for a few big meals over lots of smaller ones. Stress also forced a preferential desire for sugar and fat over regular mixed composition meals.

The study showed this happens at the level of the brain because glucocorticoids, like cortisol, affect brain chemicals, specifically dopamine and opioids that can lead towards depression or anxiety, lack of motivation, lack of spontaneous movement, and a desire for high-calorie foods. Sounds a lot like what we call emotional eating, right?

The bottom line here is that stress, when chronic and persistent, affects brain chemistry in a way that changes behavior. These behaviors are directly correlated to obesity and appear to be coming from more unconscious centers of the brain.

Cortisol and Insulin – a bad combination

In addition to the brain effects that can alter the types of calories we eat and how much activity we do, this same chronic stress has negative consequences on the type of calories we burn and where we store fat. When cortisol and other stress hormones are around in high amounts fat is burned from the arms and legs and redistributed to the middle.

This has much to do with the liver since, as discussed above, it plays a major role in responding to the demands of adrenal hormones by upregulating glucose production and raising blood sugar. However, high blood sugar levels are damaging to physiology so the body compensates by releasing insulin to lower the sugar and push it back into the cells.

Insulin is an interesting hormone since it signals the body to store fat and not burn it. The combination of high insulin with high cortisol is a very bad mix and does make you fat. Whereas cortisol alone will burn both muscle and fat for energy, the addition of insulin makes the use of fat much less likely forcing the body to use muscle instead.

In addition, this combination may burn fat and muscle from the arms and legs, but it increases fat storage at the belly. This too may be an ancient adaptation for physiology that did not always see a ready supply of food. Belly fat is unique because it is anatomically closer to the liver allowing a quick and readily accessible fuel source from which the liver can draw.

Animals preparing for hibernation show this same distribution of fat storage, and it helps them survive many months without food. Humans no longer need to deal with this reality, but our ancient metabolism does not know the difference.

There is a lot of misunderstanding about stress and cortisol. It is commonly assumed that people that store fat at the belly simply produce excess cortisol and that is what causes the problem. However, obese individuals do not have higher systemic levels of cortisol compared to thin people.

A 1996 study in the May issue of Obesity Research showed obese individuals can have lower, not higher, resting cortisol levels in the morning. Another study published in the Feb 2000 issue of the Journal of Internal Medicine pointed out that obese women can have lower, not higher systemic levels of cortisol. This is often a point of confusion among people who point to cortisol as being the major cause of belly fat.

This is where an understanding of relative cortisol comes in as well as long-term cortisol exposure. If cortisol is in a higher ratio to HGH and testosterone whether or not is it considered absolutely high or not, it will cause problems. In addition, chronic persistent stress will cause changes in the adrenal system that can lead to “adrenal fatigue” or adrenal insufficiency, characterized by low cortisol.

Savvy personal trainers and fitness enthusiasts should know the difference. Despite what the infomercials say, it is not cortisol alone causing belly fat.

The most important thing to remember when it comes to hormones is that they never act alone. Hormones are like people and will behave differently depending on the other hormones they are “socializing” with. When you add cortisol and insulin into the mix, what you will see is a whole host of changes that explain exactly what is happening and why stress makes us fat.

The modern-day diet, lifestyle, and exercise habits make us all have relatively higher levels of cortisol compared to other hormones. Whether we actually get fat or not depends on how much insulin we have as well.

Here is how it works. Remember how the HPA axis regulates stress function and when you are under stress it causes the release of the stress hormones, which then release blood sugar? If that blood sugar is not used through activity, the body will then secrete insulin to lower the blood sugar.

You can think of cortisol and insulin-like the opposite ends of a seesaw. In early stress, the two will work back and forth raising and then lowering blood sugar to help you cope with stress. However, over time with continuous stimulation, the body will require more and more of each hormone to deliver the same response. In time you end up with relatively higher insulin and cortisol levels beyond the ability of other fat-burning hormones to oppose them.

Remember that cortisol is a fat burner as well as a muscle burner, but when insulin is around with it, the body will burn muscle NOT fat since insulin puts a lock-down on fat release. This causes leaner arms and legs and fat storage around the middle.

The fat storage around the middle IS caused by cortisol, but not without the help of insulin and lower levels of HGH and testosterone. Insulin and cortisol together alter lipoprotein lipase, the key-regulating enzyme that leads to fat storage rather than fat breakdown, and this action is directed right at the belly.

One other insidious aspect of high amounts of cortisol during chronic and repeated stress is its relationship with a compound called NPY. Cortisol causes the nervous system to release more NPY and NPY causes fat cells to mature and grow. 

Putting the breaks on belly fat, HGH and Testosterone

If the effects of insulin and cortisol were not bad enough, it is made worse by the decreased secretion of HGH. Sleep, intense exercise, and adequate protein intake are the only known stimuli to reliably increase HGH in men and women.

We have become a society that brags about not getting enough sleep, often under eat protein, and focuses on low intensity and aerobic centered exercise. None of these behaviors help the situation. HGH counters the effect of insulin and cortisol by “wrestling” cortisol away from the negative influences of insulin.

When adequate HGH is present with cortisol the fat-storing effects at the belly may be blocked. An August 2008 study in the American Journal of Physiology, Endocrinology, and Metabolism showed that a high Cortisol to HGH ratio led to abdominal obesity in women.

A study in the 2000 issue of the Journal of Clinical Endocrinology and Metabolism (Volume 85 # 2), shows that not only does HGH block the fat-storing effects of stress-induced insulin and cortisol, but may alter the effect to be one of muscle building and fat burning instead.

Based on these effects, stress can either make you fat or get you lean. It really all depends on your choice to move or sit.

What can you do?

Once you understand the admittedly difficult mechanisms involved in stress and fat, you are ready to attack stress head-on. Here are 6 ways to beat the fat-storing effects of stress.

1) Don’t fast if you are stress sensitive. By eating normally you will immediately blunt the rising cortisol levels that can occur in a fasting state. Meals should focus on a balanced ratio of carbs, fat, and protein and not the standard American diet of cereal, toast, juice, and coffee, which to your body register as sugar, sugar, sugar, and stress and increases insulin and cortisol above and beyond healthy levels.

2) Exercise, exercise intensely and exercise with weights. To counter the negative effects of stress, you must produce an adequate release of HGH and testosterone.

3) Sleep. If you don’t sleep, you have already created an unfavorable stress response and circumvented your natural release of the anti-stress hormone HGH.

4) Substitute protein for sugar. Rather than going for sugar, increase your protein. This will block the muscle wasting effects of cortisol by making amino acids available without the need to tear down muscle. Protein will also release another hormone that counters the effect of insulin.

5) Use cocoa. We are not talking about chocolate with sugar, but the addition of 100% unsweetened cocoa powder to the diet. This increases the levels of PEA (phenyl-Ethyl Amine) which is a dopamine mimicker and will decrease the pleasure-seeking behaviors stress induces. This will decrease cravings and the excess intake of fat and sugar.

6) Eat 4-6 times per day instead of 1-3. By eating smaller meals more often you will reduce the “fasting effect”. Research shows that animals that are hungry or fasted eat larger meals and produce more insulin and cortisol in response to those meals.

One last word for personal trainers and serious exercise enthusiasts, exercise can be stressful too. Long workouts that are heavy on cardiovascular training and light on resistance training can skew the adrenal stress mechanisms further towards excess cortisol and low HGH in those who are susceptible.

If you are having trouble burning fat especially at the belly, you may want to consider harder workouts that are shorter. A twenty-minute workout that brings the body to full fatigue may be a better option to remove belly fat than a two-hour jog in the park. See you at the gym. 

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